49 CFR Appendix D to Part 227 - Audiometric Test Rooms

Code of Federal Regulations, 2010 CFR

2010-10-01

... sound pressure levels exceeding those in Table D-1 when measured by equipment conforming at least to the..._regulations/ibr_locations.html. Table D-1—Maximum Allowable Octave-Band Sound Pressure Levels for Audiometric Test Rooms Octave-band center frequency (Hz) 500 1000 2000 4000 8000 Sound pressure levels—supra-aural...

Development and application of an empirical probability distribution for the prediction error of re-entry body maximum dynamic pressure

NASA Technical Reports Server (NTRS)

Lanzi, R. James; Vincent, Brett T.

1993-01-01

The relationship between actual and predicted re-entry maximum dynamic pressure is characterized using a probability density function and a cumulative distribution function derived from sounding rocket flight data. This paper explores the properties of this distribution and demonstrates applications of this data with observed sounding rocket re-entry body damage characteristics to assess probabilities of sustaining various levels of heating damage. The results from this paper effectively bridge the gap existing in sounding rocket reentry analysis between the known damage level/flight environment relationships and the predicted flight environment.

Output levels of commercially available portable compact disc players and the potential risk to hearing.

PubMed

Fligor, Brian J; Cox, L Clarke

2004-12-01

To measure the sound levels generated by the headphones of commercially available portable compact disc players and provide hearing healthcare providers with safety guidelines based on a theoretical noise dose model. Using a Knowles Electronics Manikin for Acoustical Research and a personal computer, output levels across volume control settings were recorded from headphones driven by a standard signal (white noise) and compared with output levels from music samples of eight different genres. Many commercially available models from different manufacturers were investigated. Several different styles of headphones (insert, supra-aural, vertical, and circumaural) were used to determine if style of headphone influenced output level. Free-field equivalent sound pressure levels measured at maximum volume control setting ranged from 91 dBA to 121 dBA. Output levels varied across manufacturers and style of headphone, although generally the smaller the headphone, the higher the sound level for a given volume control setting. Specifically, in one manufacturer, insert earphones increased output level 7-9 dB, relative to the output from stock headphones included in the purchase of the CD player. In a few headphone-CD player combinations, peak sound pressure levels exceeded 130 dB SPL. Based on measured sound pressure levels across systems and the noise dose model recommended by National Institute for Occupational Safety and Health for protecting the occupational worker, a maximum permissible noise dose would typically be reached within 1 hr of listening with the volume control set to 70% of maximum gain using supra-aural headphones. Using headphones that resulted in boosting the output level (e.g., insert earphones used in this study) would significantly decrease the maximum safe volume control setting; this effect was unpredictable from one manufacturer to another. In the interest of providing a straightforward recommendation that should protect the hearing of the majority of consumers, reasonable guidelines would include a recommendation to limit headphone use to 1 hr or less per day if using supra-aural style headphones at a gain control setting of 60% of maximum.

How effectively do horizontal and vertical response strategies of long-finned pilot whales reduce sound exposure from naval sonar?

PubMed

Wensveen, Paul J; von Benda-Beckmann, Alexander M; Ainslie, Michael A; Lam, Frans-Peter A; Kvadsheim, Petter H; Tyack, Peter L; Miller, Patrick J O

2015-05-01

The behaviour of a marine mammal near a noise source can modulate the sound exposure it receives. We demonstrate that two long-finned pilot whales both surfaced in synchrony with consecutive arrivals of multiple sonar pulses. We then assess the effect of surfacing and other behavioural response strategies on the received cumulative sound exposure levels and maximum sound pressure levels (SPLs) by modelling realistic spatiotemporal interactions of a pilot whale with an approaching source. Under the propagation conditions of our model, some response strategies observed in the wild were effective in reducing received levels (e.g. movement perpendicular to the source's line of approach), but others were not (e.g. switching from deep to shallow diving; synchronous surfacing after maximum SPLs). Our study exemplifies how simulations of source-whale interactions guided by detailed observational data can improve our understanding about motivations behind behaviour responses observed in the wild (e.g., reducing sound exposure, prey movement). Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of hearing protection used by police officers in the shooting range.

PubMed

Guida, Heraldo Lorena; Taxini, Carla Linhares; Gonçalves, Claudia Giglio de Oliveira; Valenti, Vitor Engrácia

2014-01-01

Impact noise is characterized by acoustic energy peaks that last less than a second, at intervals of more than 1s. To quantify the levels of impact noise to which police officers are exposed during activities at the shooting range and to evaluate the attenuation of the hearing protector. Measurements were performed in the shooting range of a military police department. An SV 102 audiodosimeter (Svantek) was used to measure sound pressure levels. Two microphones were used simultaneously: one external and one insertion type; the firearm used was a 0.40 Taurus® rimless pistol. The values obtained with the external microphone were 146 dBC (peak), and a maximum sound level of 129.4 dBC (fast). The results obtained with the insertion microphone were 138.7 dBC (peak), and a maximum sound level of 121.6 dBC (fast). The findings showed high levels of sound pressure in the shooting range, which exceeded the maximum recommended noise (120 dBC), even when measured through the insertion microphone. Therefore, alternatives to improve the performance of hearing protection should be considered. Copyright © 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

The sounds of handheld audio players.

PubMed

Rudy, Susan F

2007-01-01

Hearing experts and public health organizations have longstanding hearing safety concerns about personal handheld audio devices, which are growing in both number and popularity. This paper reviews the maximum sound levels of handheld compact disc players, MP3 players, and an iPod. It further reviews device factors that influence the sound levels produced by these audio devices and ways to reduce the risk to hearing during their use.

Sound Standards for Schools "Unsound."

ERIC Educational Resources Information Center

Davis, Don

2002-01-01

Criticizes new classroom sound standard proposed by the American National Standards Institute that sets maximum background sound level at 35 decibels (described as "a whisper at 2 meters"). Argues that new standard is too costly for schools to implement, is not recommended by the medical community, and cannot be achieved by construction…

Semi-empirical airframe noise prediction model

NASA Technical Reports Server (NTRS)

Hersh, A. S.; Putnam, T. W.; Lasagna, P. L.; Burcham, F. W., Jr.

1976-01-01

A semi-empirical maximum overall sound pressure level (OASPL) airframe noise model was derived. The noise radiated from aircraft wings and flaps was modeled by using the trailing-edge diffracted quadrupole sound theory derived by Ffowcs Williams and Hall. The noise radiated from the landing gear was modeled by using the acoustic dipole sound theory derived by Curle. The model was successfully correlated with maximum OASPL flyover noise measurements obtained at the NASA Dryden Flight Research Center for three jet aircraft - the Lockheed JetStar, the Convair 990, and the Boeing 747 aircraft.

Application of a methodology for categorizing and differentiating urban soundscapes using acoustical descriptors and semantic-differential attributes.

PubMed

Torija, Antonio J; Ruiz, Diego P; Ramos-Ridao, A F

2013-07-01

A subjective and physical categorization of an ambient sound is the first step to evaluate the soundscape and provides a basis for designing or adapting this ambient sound to match people's expectations. For this reason, the main goal of this work is to develop a categorization and differentiation analysis of soundscapes on the basis of acoustical and perceptual variables. A hierarchical cluster analysis, using 15 semantic-differential attributes and acoustical descriptors to include an equivalent sound-pressure level, maximum-minimum sound-pressure level, impulsiveness of the sound-pressure level, sound-pressure level time course, and spectral composition, was conducted to classify soundscapes into different typologies. This analysis identified 15 different soundscape typologies. Furthermore, based on a discriminant analysis the acoustical descriptors, the crest factor (impulsiveness of the sound-pressure level), and the sound level at 125 Hz were found to be the acoustical variables with the highest impact in the differentiation of the recognized types of soundscapes. Finally, to determine how the different soundscape typologies differed from each other, both subjectively and acoustically, a study was performed.

Sound absorption study on acoustic panel from kapok fiber and egg tray

NASA Astrophysics Data System (ADS)

Kaamin, Masiri; Mahir, Nurul Syazwani Mohd; Kadir, Aslila Abd; Hamid, Nor Baizura; Mokhtar, Mardiha; Ngadiman, Norhayati

2017-12-01

Noise also known as a sound, especially one that is loud or unpleasant or that causes disruption. The level of noise can be reduced by using sound absorption panel. Currently, the market produces sound absorption panel, which use synthetic fibers that can cause harmful effects to the health of consumers. An awareness of using natural fibers from natural materials gets attention of some parties to use it as a sound absorbing material. Therefore, this study was conducted to investigate the potential of sound absorption panel using egg trays and kapok fibers. The test involved in this study was impedance tube test which aims to get sound absorption coefficient (SAC). The results showed that there was good sound absorption at low frequency from 0 Hz up to 900 Hz where the maximum absorption coefficient was 0.950 while the maximum absorption at high frequencies was 0.799. Through the noise reduction coefficient (NRC), the material produced NRC of 0.57 indicates that the materials are very absorbing. In addition, the reverberation room test was carried out to get the value of reverberation time (RT) in unit seconds. Overall this panel showed good results at low frequencies between 0 Hz up to 1500 Hz. In that range of frequency, the maximum reverberation time for the panel was 3.784 seconds compared to the maximum reverberation time for an empty room was 5.798 seconds. This study indicated that kapok fiber and egg tray as the material of absorption panel has a potential as environmental and cheap products in absorbing sound at low frequency.

Excessive exposure of sick neonates to sound during transport

PubMed Central

Buckland, L; Austin, N; Jackson, A; Inder, T

2003-01-01

Objective: To determine the levels of sound to which infants are exposed during routine transport by ambulance, aircraft, and helicopter. Design: Sound levels during 38 consecutive journeys from a regional level III neonatal intensive care unit were recorded using a calibrated data logging sound meter (Quest 2900). The meter was set to record "A" weighted slow response integrated sound levels, which emulates the response of the human ear, and "C" weighted response sound levels as a measure of total sound level exposure for all frequencies. The information was downloaded to a computer using MS HyperTerminal. The resulting data were stored, and a graphical profile was generated for each journey using SigmaPlot software. Setting: Eight journeys involved ambulance transport on country roads, 24 involved fixed wing aircraft, and four were by helicopter. Main outcome measures: Relations between decibel levels and events or changes in transport mode were established by correlating the time logged on the sound meter with the standard transport documentation sheet. Results: The highest sound levels were recorded during air transport. However, mean sound levels for all modes of transport exceeded the recommended levels for neonatal intensive care. The maximum sound levels recorded were extremely high at greater than 80 dB in the "A" weighted hearing range and greater than 120 dB in the total frequency range. Conclusions: This study raises major concerns about the excessive exposure of the sick newborn to sound during transportation. PMID:14602701

Sound pressure levels generated at risk volume steps of portable listening devices: types of smartphone and genres of music.

PubMed

Kim, Gibbeum; Han, Woojae

2018-05-01

The present study estimated the sound pressure levels of various music genres at the volume steps that contemporary smartphones deliver, because these levels put the listener at potential risk for hearing loss. Using six different smartphones (Galaxy S6, Galaxy Note 3, iPhone 5S, iPhone 6, LG G2, and LG G3), the sound pressure levels for three genres of K-pop music (dance-pop, hip-hop, and pop-ballad) and a Billboard pop chart of assorted genres were measured through an earbud for the first risk volume that was at the risk sign proposed by the smartphones, as well as consecutive higher volumes using a sound level meter and artificial mastoid. The first risk volume step of the Galaxy S6 and the LG G2, among the six smartphones, had the significantly lowest (84.1 dBA) and highest output levels (92.4 dBA), respectively. As the volume step increased, so did the sound pressure levels. The iPhone 6 was loudest (113.1 dBA) at the maximum volume step. Of the music genres, dance-pop showed the highest output level (91.1 dBA) for all smartphones. Within the frequency range of 20~ 20,000 Hz, the sound pressure level peaked at 2000 Hz for all the smartphones. The results showed that the sound pressure levels of either the first volume step or the maximum volume step were not the same for the different smartphone models and genres of music, which means that the risk volume sign and its output levels should be unified across the devices for their users. In addition, the risk volume steps proposed by the latest smartphone models are high enough to cause noise-induced hearing loss if their users habitually listen to music at those levels.

Effect of Human Auditory Efferent Feedback on Cochlear Gain and Compression

PubMed Central

Drga, Vit; Plack, Christopher J.

2014-01-01

The mammalian auditory system includes a brainstem-mediated efferent pathway from the superior olivary complex by way of the medial olivocochlear system, which reduces the cochlear response to sound (Warr and Guinan, 1979; Liberman et al., 1996). The human medial olivocochlear response has an onset delay of between 25 and 40 ms and rise and decay constants in the region of 280 and 160 ms, respectively (Backus and Guinan, 2006). Physiological studies with nonhuman mammals indicate that onset and decay characteristics of efferent activation are dependent on the temporal and level characteristics of the auditory stimulus (Bacon and Smith, 1991; Guinan and Stankovic, 1996). This study uses a novel psychoacoustical masking technique using a precursor sound to obtain a measure of the efferent effect in humans. This technique avoids confounds currently associated with other psychoacoustical measures. Both temporal and level dependency of the efferent effect was measured, providing a comprehensive measure of the effect of human auditory efferents on cochlear gain and compression. Results indicate that a precursor (>20 dB SPL) induced efferent activation, resulting in a decrease in both maximum gain and maximum compression, with linearization of the compressive function for input sound levels between 50 and 70 dB SPL. Estimated gain decreased as precursor level increased, and increased as the silent interval between the precursor and combined masker-signal stimulus increased, consistent with a decay of the efferent effect. Human auditory efferent activation linearizes the cochlear response for mid-level sounds while reducing maximum gain. PMID:25392499

20 Years of sea-levels, accretion, and vegetation on two Long Island Sound salt marshes

EPA Science Inventory

The long-term 1939-2013 rate of RSLR (Relative Sea-Level Rise) at the New London, CT tide gauge is ~2.6 mm/yr, near the maximum rate of salt marsh accretion reported in eastern Long Island Sound salt marshes. Consistent with recent literature RSLR at New London has accelerated si...

Assessment of sound levels in a neonatal intensive care unit in tabriz, iran.

PubMed

Valizadeh, Sousan; Bagher Hosseini, Mohammad; Alavi, Nasrinsadat; Asadollahi, Malihe; Kashefimehr, Siamak

2013-03-01

High levels of sound have several negative effects, such as noise-induced hearing loss and delayed growth and development, on premature infants in neonatal intensive care units (NICUs). In order to reduce sound levels, they should first be measured. This study was performed to assess sound levels and determine sources of noise in the NICU of Alzahra Teaching Hospital (Tabriz, Iran). In a descriptive study, 24 hours in 4 workdays were randomly selected. Equivalent continuous sound level (Leq), sound level that is exceeded only 10% of the time (L10), maximum sound level (Lmax), and peak instantaneous sound pressure level (Lzpeak) were measured by CEL-440 sound level meter (SLM) at 6 fixed locations in the NICU. Data was collected using a questionnaire. SPSS13 was then used for data analysis. Mean values of Leq, L10, and Lmax were determined as 63.46 dBA, 65.81 dBA, and 71.30 dBA, respectively. They were all higher than standard levels (Leq < 45 dB, L10 ≤50 dB, and Lmax ≤65 dB). The highest Leq was measured at the time of nurse rounds. Leq was directly correlated with the number of staff members present in the ward. Finally, sources of noise were ordered based on their intensity. Considering that sound levels were higher than standard levels in our studied NICU, it is necessary to adopt policies to reduce sound.

Assessment of Sound Levels in a Neonatal Intensive Care Unit in Tabriz, Iran

PubMed Central

Valizadeh, Sousan; Bagher Hosseini, Mohammad; Alavi, Nasrinsadat; Asadollahi, Malihe; Kashefimehr, Siamak

2013-01-01

Introduction: High levels of sound have several negative effects, such as noise-induced hearing loss and delayed growth and development, on premature infants in neonatal intensive care units (NICUs). In order to reduce sound levels, they should first be measured. This study was performed to assess sound levels and determine sources of noise in the NICU of Alzahra Teaching Hospital (Tabriz, Iran). Methods: In a descriptive study, 24 hours in 4 workdays were randomly selected. Equivalent continuous sound level (Leq), sound level that is exceeded only 10% of the time (L10), maximum sound level (Lmax), and peak instantaneous sound pressure level (Lzpeak) were measured by CEL-440 sound level meter (SLM) at 6 fixed locations in the NICU. Data was collected using a questionnaire. SPSS13 was then used for data analysis. Results: Mean values of Leq, L10, and Lmax were determined as 63.46 dBA, 65.81 dBA, and 71.30 dBA, respectively. They were all higher than standard levels (Leq < 45 dB, L10 ≤50 dB, and Lmax ≤65 dB). The highest Leq was measured at the time of nurse rounds. Leq was directly correlated with the number of staff members present in the ward. Finally, sources of noise were ordered based on their intensity. Conclusion: Considering that sound levels were higher than standard levels in our studied NICU, it is necessary to adopt policies to reduce sound. PMID:25276706

Improvement of intensive care unit sound environment and analyses of consequences on sleep: an experimental study.

PubMed

Persson Waye, Kerstin; Elmenhorst, Eva-Maria; Croy, Ilona; Pedersen, Eja

2013-12-01

Uninterrupted sleep is of vital importance for restoration and regaining health. In intensive care units (ICUs) where recovering and healing is crucial, patients' sleep often is fragmented and disturbed due to noise from activities from oneself, other patients, and alarms. The aim of our study was to explore if sleep could be improved by modifying the sound environment in a way that is practically feasible in ICUs. We studied the effects of originally recorded ICU noise and peak reduced ICU noise on sleep in healthy male participants. Sleep was registered with polysomnography (PSG) during four nights: one adaptation night, one reference (REF) night, and the two exposed nights with similar equivalent sound levels (47dB LAeq) but different maximum sound levels (56- vs 64-dB LAFmax). The participants answered questionnaires and saliva cortisol was sampled in the morning. During ICU exposure nights, sleep was more fragmented with less slow-wave sleep (SWS), more arousals, and more time awake. The effects of reduced maximum sound level were minor. The subjective data supported the polysomnographic findings, though cortisol levels were not significantly affected by the exposure conditions. Noise in ICUs impairs sleep and the reduction of maximal A-weighted levels from 64 to 56dB is not enough to have a clear improved effect on sleep quality. Copyright © 2013 Elsevier B.V. All rights reserved.

Development and modification of a Gaussian and non-Gaussian noise exposure system

NASA Astrophysics Data System (ADS)

Schlag, Adam W.

Millions of people across the world currently have noise induced hearing loss, and many are working in conditions with both continuous Gaussian and non-Gaussian noises that could affect their hearing. It was hypothesized that the energy of the noise was the cause of the hearing loss and did not depend on temporal pattern of a noise. This was referred to as the equal energy hypothesis. This hypothesis has been shown to have limitations though. This means that there is a difference in the types of noise a person receives to induce hearing loss and it is necessary to build a system that can easily mimic various conditions to conduct research. This study builds a system that can produce both non-Gaussian impulse/impact noises and continuous Gaussian noise. It was found that the peak sound pressure level of the system could reach well above the needed 120 dB level to represent acoustic trauma and could replicate well above the 85 dB A-weighted sound pressure level to produce conditions of gradual developing hearing loss. The system reached a maximum of 150 dB sound peak pressure level and a maximum of 133 dB A-weighted sound pressure level. Various parameters could easily be adjusted to control the sound, such as the high and low cutoff frequency to center the sound at 4 kHz. The system build can easily be adjusted to create numerous sound conditions and will hopefully be modified and improved in hopes of eventually being used for animal studies to lead to the creation of a method to treat or prevent noise induced hearing loss.

Optimum data analysis procedures for Titan 4 and Space Shuttle payload acoustic measurements during lift-off

NASA Technical Reports Server (NTRS)

Piersol, Allan G.

1991-01-01

Analytical expressions have been derived to describe the mean square error in the estimation of the maximum rms value computed from a step-wise (or running) time average of a nonstationary random signal. These analytical expressions have been applied to the problem of selecting the optimum averaging times that will minimize the total mean square errors in estimates of the maximum sound pressure levels measured inside the Titan IV payload fairing (PLF) and the Space Shuttle payload bay (PLB) during lift-off. Based on evaluations of typical Titan IV and Space Shuttle launch data, it has been determined that the optimum averaging times for computing the maximum levels are (1) T (sub o) = 1.14 sec for the maximum overall level, and T(sub oi) = 4.88 f (sub i) (exp -0.2) sec for the maximum 1/3 octave band levels inside the Titan IV PLF, and (2) T (sub o) = 1.65 sec for the maximum overall level, and T (sub oi) = 7.10 f (sub i) (exp -0.2) sec for the maximum 1/3 octave band levels inside the Space Shuttle PLB, where f (sub i) is the 1/3 octave band center frequency. However, the results for both vehicles indicate that the total rms error in the maximum level estimates will be within 25 percent the minimum error for all averaging times within plus or minus 50 percent of the optimum averaging time, so a precise selection of the exact optimum averaging time is not critical. Based on these results, linear averaging times (T) are recommended for computing the maximum sound pressure level during lift-off.

Optimizing Classroom Acoustics Using Computer Model Studies.

ERIC Educational Resources Information Center

Reich, Rebecca; Bradley, John

1998-01-01

Investigates conditions relating to the maximum useful-to-detrimental sound ratios present in classrooms and determining the optimum conditions for speech intelligibility. Reveals that speech intelligibility is more strongly influenced by ambient noise levels and that the optimal location for sound absorbing material is on a classroom's upper…

Environmental Assessment: Installation Development at Sheppard Air Force Base, Texas

DTIC Science & Technology

2007-05-01

column, or in topographic depressions. Water is then utilized by plants and is respired, or it moves slowly into groundwater and/or eventually to surface...water bodies where it slowly moves through the hydrologic cycle. Removal of vegetation decreases infiltration into the soil column and thereby...School District JP-4 jet propulsion fuel 4 kts knots Ldn Day- Night Average Sound Level Leq equivalent noise level Lmax maximum sound level lb pound

The annoyance of impulsive helicopter noise

NASA Technical Reports Server (NTRS)

Karamcheti, K.

1981-01-01

A total of 96 impulsive and non-impulsive sounds were rated for annoyance by 10 subjects. The signals had the same amplitude spectrum with a maximum frequency of 4.75 kHz. By changing the phase of the spectral components different levels of impulsivity were obtained. The signals had coefficients of impulsivity of 10,8, 7,9, and -0.2 respectively. Further, signals had intensity levels 89 and 95 dBA, pulse repetition rates 10 and 20 Hz, and half the signals had pink noise added at a level 12 dBA lower than the level of the sound. The significant results were: The four females and six male subjects rated the impulsive sounds respectively 3.7 dB less annoying and 2.6 dB more annoying than the non-impulsive sounds. Overall, impulsivity had no effect. The hish pulse repetition rate increased annoyance by 2.2 dB. Addition of pink noise increased annoyance of the non-impulsive sounds 1.2 dB, but decreased the annoyance of the impulsive sounds 0.5 dB.

Noise and low-frequency sound levels due to aerial fireworks and prediction of the occupational exposure of pyrotechnicians to noise

PubMed Central

Tanaka, Tagayasu; Inaba, Ryoichi; Aoyama, Atsuhito

2016-01-01

Objectives: This study investigated the actual situation of noise and low-frequency sounds in firework events and their impact on pyrotechnicians. Methods: Data on firework noise and low-frequency sounds were obtained at a point located approximately 100 m away from the launch site of a firework display held in "A" City in 2013. We obtained the data by continuously measuring and analyzing the equivalent continuous sound level (Leq) and the one-third octave band of the noise and low-frequency sounds emanating from the major firework detonations, and predicted sound levels at the original launch site. Results: Sound levels of 100-115 dB and low-frequency sounds of 100-125 dB were observed at night. The maximum and mean Leq values were 97 and 95 dB, respectively. The launching noise level predicted from the sounds (85 dB) at the noise measurement point was 133 dB. Occupational exposure to noise for pyrotechnicians at the remote operation point (located 20-30 m away from the launch site) was estimated to be below 100 dB. Conclusions: Pyrotechnicians are exposed to very loud noise (>100 dB) at the launch point. We believe that it is necessary to implement measures such as fixing earplugs or earmuffs, posting a warning at the workplace, and executing a remote launching operation to prevent hearing loss caused by occupational exposure of pyrotechnicians to noise. It is predicted that both sound levels and low-frequency sounds would be reduced by approximately 35 dB at the remote operation site. PMID:27725489

Noise and low-frequency sound levels due to aerial fireworks and prediction of the occupational exposure of pyrotechnicians to noise.

PubMed

Tanaka, Tagayasu; Inaba, Ryoichi; Aoyama, Atsuhito

2016-11-29

This study investigated the actual situation of noise and low-frequency sounds in firework events and their impact on pyrotechnicians. Data on firework noise and low-frequency sounds were obtained at a point located approximately 100 m away from the launch site of a firework display held in "A" City in 2013. We obtained the data by continuously measuring and analyzing the equivalent continuous sound level (Leq) and the one-third octave band of the noise and low-frequency sounds emanating from the major firework detonations, and predicted sound levels at the original launch site. Sound levels of 100-115 dB and low-frequency sounds of 100-125 dB were observed at night. The maximum and mean Leq values were 97 and 95 dB, respectively. The launching noise level predicted from the sounds (85 dB) at the noise measurement point was 133 dB. Occupational exposure to noise for pyrotechnicians at the remote operation point (located 20-30 m away from the launch site) was estimated to be below 100 dB. Pyrotechnicians are exposed to very loud noise (>100 dB) at the launch point. We believe that it is necessary to implement measures such as fixing earplugs or earmuffs, posting a warning at the workplace, and executing a remote launching operation to prevent hearing loss caused by occupational exposure of pyrotechnicians to noise. It is predicted that both sound levels and low-frequency sounds would be reduced by approximately 35 dB at the remote operation site.

Wind-tunnel acoustic results of two rotor models with several tip designs

NASA Technical Reports Server (NTRS)

Martin, R. M.; Connor, A. B.

1986-01-01

A three-phase research program has been undertaken to study the acoustic signals due to the aerodynamic interaction of rotorcraft main rotors and tail rotors. During the first phase, two different rotor models with several interchangeable tips were tested in the Langley 4- by 7-Meter Tunnel on the U.S. Army rotor model system. An extensive acoustic data base was acquired, with special emphasis on blade-vortex interaction (BVI) noise. The details of the experimental procedure, acoustic data acquisition, and reduction are documented. The overall sound pressure level (OASPL) of the high-twist rotor systems is relatively insensitive to flight speed but generally increases with rotor tip-path-plane angle. The OASPL of the high-twist rotors is dominated by acoustic energy in the low-frequency harmonics. The OASPL of the low-twist rotor systems shows more dependence on flight speed than the high-twist rotors, in addition to being quite sensitive to tip-path-plane angle. An integrated band-limited sound pressure level, limited by 500 to 3000 Hz, is a useful metric to quantify the occurrence of BVI noise. The OASPL of the low-twist rotors is strongly influenced by the band-limited sound levels, indicating that the blade-vortex impulsive noise is a dominant noise source for this rotor design. The midfrequency acoustic levels for both rotors show a very strong dependence on rotor tip-path-plane angle. The tip-path-plane angle at which the maximum midfrequency sound level occurs consistently decreases with increasing flight speed. The maximum midfrequency sound level measured at a given location is constant regardless of the flight speed.

Neural population encoding and decoding of sound source location across sound level in the rabbit inferior colliculus

PubMed Central

Delgutte, Bertrand

2015-01-01

At lower levels of sensory processing, the representation of a stimulus feature in the response of a neural population can vary in complex ways across different stimulus intensities, potentially changing the amount of feature-relevant information in the response. How higher-level neural circuits could implement feature decoding computations that compensate for these intensity-dependent variations remains unclear. Here we focused on neurons in the inferior colliculus (IC) of unanesthetized rabbits, whose firing rates are sensitive to both the azimuthal position of a sound source and its sound level. We found that the azimuth tuning curves of an IC neuron at different sound levels tend to be linear transformations of each other. These transformations could either increase or decrease the mutual information between source azimuth and spike count with increasing level for individual neurons, yet population azimuthal information remained constant across the absolute sound levels tested (35, 50, and 65 dB SPL), as inferred from the performance of a maximum-likelihood neural population decoder. We harnessed evidence of level-dependent linear transformations to reduce the number of free parameters in the creation of an accurate cross-level population decoder of azimuth. Interestingly, this decoder predicts monotonic azimuth tuning curves, broadly sensitive to contralateral azimuths, in neurons at higher levels in the auditory pathway. PMID:26490292

Evaluation of Noise Exposure Secondary to Wind Noise in Cyclists.

PubMed

Seidman, Michael D; Wertz, Anna G; Smith, Matthew M; Jacob, Steve; Ahsan, Syed F

2017-11-01

Objective Determine if the noise levels of wind exposure experienced by cyclists reach levels that could contribute to noise-induced hearing loss. Study Design Industrial lab research. Setting Industrial wind tunnel. Subjects and Methods A commercial-grade electric wind tunnel was used to simulate different speeds encountered by a cyclist. A single cyclist was used during the simulation for audiometric measurements. Microphones attached near the ears of the cyclist were used to measure the sound (dB sound pressure level) experienced by the cyclist. Loudness levels were measured with the head positioned at 15-degree increments from 0 degrees to 180 degrees relative to the oncoming wind at different speeds (10-60 mph). Results Wind noise ranged from 84.9 dB at 10 mph and increased proportionally with speed to a maximum of 120.3 dB at 60 mph. The maximum of 120.3 dB was measured at the downwind ear when the ear was 90 degrees away from the wind. Conclusions Wind noise experienced by a cyclist is proportional to the speed and the directionality of the wind current. Turbulent air flow patterns are observed that contribute to increased sound exposure in the downwind ear. Consideration of ear deflection equipment without compromising sound awareness for cyclists during prolonged rides is advised to avoid potential noise trauma. Future research is warranted and can include long-term studies including dosimetry measures of the sound and yearly pre- and postexposure audiograms of cyclists to detect if any hearing loss occurs with long-term cycling.

Vandenberg Air Force Base Upper Level Wind Launch Weather Constraints

NASA Technical Reports Server (NTRS)

Shafer, Jaclyn A.; Wheeler, Mark M.

2012-01-01

The 30th Operational Support Squadron Weather Flight (30 OSSWF) provides comprehensive weather services to the space program at Vandenberg Air Force Base (VAFB) in California. One of their responsibilities is to monitor upper-level winds to ensure safe launch operations of the Minuteman III ballistic missile. The 30 OSSWF tasked the Applied Meteorology Unit (AMU) to analyze VAFB sounding data with the goal of determining the probability of violating (PoV) their upper-level thresholds for wind speed and shear constraints specific to this launch vehicle, and to develop a tool that will calculate the PoV of each constraint on the day of launch. In order to calculate the probability of exceeding each constraint, the AMU collected and analyzed historical data from VAFB. The historical sounding data were retrieved from the National Oceanic and Atmospheric Administration Earth System Research Laboratory archive for the years 1994-2011 and then stratified into four sub-seasons: January-March, April-June, July-September, and October-December. The maximum wind speed and 1000-ft shear values for each sounding in each subseason were determined. To accurately calculate the PoV, the AMU determined the theoretical distributions that best fit the maximum wind speed and maximum shear datasets. Ultimately it was discovered that the maximum wind speeds follow a Gaussian distribution while the maximum shear values follow a lognormal distribution. These results were applied when calculating the averages and standard deviations needed for the historical and real-time PoV calculations. In addition to the requirements outlined in the original task plan, the AMU also included forecast sounding data from the Rapid Refresh model. This information provides further insight for the launch weather officers (LWOs) when determining if a wind constraint violation will occur over the next few hours on day of launch. The interactive graphical user interface (GUI) for this project was developed in Microsoft Excel using Visual Basic for Applications. The GUI displays the critical sounding data easily and quickly for the LWOs on day of launch. This tool will replace the existing one used by the 30 OSSWF, assist the LWOs in determining the probability of exceeding specific wind threshold values, and help to improve the overall upper winds forecast for the launch customer.

Sound levels in a neonatal intensive care unit significantly exceeded recommendations, especially inside incubators.

PubMed

Parra, Johanna; de Suremain, Aurelie; Berne Audeoud, Frederique; Ego, Anne; Debillon, Thierry

2017-12-01

This study measured sound levels in a 2008 built French neonatal intensive care unit (NICU) and compared them to the 2007 American Academy of Pediatrics (AAP) recommendations. The ultimate aim was to identify factors that could influence noise levels. The study measured sound in 17 single or double rooms in the NICU. Two dosimeters were installed in each room, one inside and one outside the incubators, and these conducted measurements over a 24-hour period. The noise metrics measured were the equivalent continuous sound level (L eq ), the maximum noise level (L max ) and the noise level exceeded for 10% of the measurement period (L 10 ). The mean L eq , L 10 and L max were 60.4, 62.1 and 89.1 decibels (dBA), which exceeded the recommended levels of 45, 50 and 65 dBA (p < 0.001), respectively. The L eq inside the incubator was significantly higher than in the room (+8 dBA, p < 0.001). None of the newborns' characteristics, the environment or medical care was correlated to an increased noise level, except for a postconceptional age below 32 weeks. The sound levels significantly exceeded the AAP recommendations, particularly inside incubators. A multipronged strategy is required to improve the sound environment and protect the neonates' sensory development. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

Time frequency analysis of sound from a maneuvering rotorcraft

NASA Astrophysics Data System (ADS)

Stephenson, James H.; Tinney, Charles E.; Greenwood, Eric; Watts, Michael E.

2014-10-01

The acoustic signatures produced by a full-scale, Bell 430 helicopter during steady-level-flight and transient roll-right maneuvers are analyzed by way of time-frequency analysis. The roll-right maneuvers comprise both a medium and a fast roll rate. Data are acquired using a single ground based microphone that are analyzed by way of the Morlet wavelet transform to extract the spectral properties and sound pressure levels as functions of time. The findings show that during maneuvering operations of the helicopter, both the overall sound pressure level and the blade-vortex interaction sound pressure level are greatest when the roll rate of the vehicle is at its maximum. The reduced inflow in the region of the rotor disk where blade-vortex interaction noise originates is determined to be the cause of the increase in noise. A local decrease in inflow reduces the miss distance of the tip vortex and thereby increases the BVI noise signature. Blade loading and advance ratios are also investigated as possible mechanisms for increased sound production, but are shown to be fairly constant throughout the maneuvers.

The isolation of low frequency impact sounds in hotel construction

NASA Astrophysics Data System (ADS)

LoVerde, John J.; Dong, David W.

2002-11-01

One of the design challenges in the acoustical design of hotels is reducing low frequency sounds from footfalls occurring on both carpeted and hard-surfaced floors. Research on low frequency impact noise [W. Blazier and R. DuPree, J. Acoust. Soc. Am. 96, 1521-1532 (1994)] resulted in a conclusion that in wood construction low frequency impact sounds were clearly audible and that feasible control methods were not available. The results of numerous FIIC (Field Impact Insulation Class) measurements performed in accordance with ASTM E1007 indicate the lack of correlation between FIIC ratings and the reaction of occupants in the room below. The measurements presented include FIIC ratings and sound pressure level measurements below the ASTM E1007 low frequency limit of 100 Hertz, and reveal that excessive sound levels in the frequency range of 63 to 100 Hertz correlate with occupant complaints. Based upon this history, a tentative criterion for maximum impact sound level in the low frequency range is presented. The results presented of modifying existing constructions to reduce the transmission of impact sounds at low frequencies indicate that there may be practical solutions to this longstanding problem.

The acoustical cues to sound location in the Guinea pig (cavia porcellus)

PubMed Central

Greene, Nathanial T; Anbuhl, Kelsey L; Williams, Whitney; Tollin, Daniel J.

2014-01-01

There are three main acoustical cues to sound location, each attributable to space-and frequency-dependent filtering of the propagating sound waves by the outer ears, head, and torso: Interaural differences in time (ITD) and level (ILD) as well as monaural spectral shape cues. While the guinea pig has been a common model for studying the anatomy, physiology, and behavior of binaural and spatial hearing, extensive measurements of their available acoustical cues are lacking. Here, these cues were determined from directional transfer functions (DTFs), the directional components of the head-related transfer functions, for eleven adult guinea pigs. In the frontal hemisphere, monaural spectral notches were present for frequencies from ~10 to 20 kHz; in general, the notch frequency increased with increasing sound source elevation and in azimuth toward the contralateral ear. The maximum ITDs calculated from low-pass filtered (2 kHz cutoff frequency) DTFs were ~250 µs, whereas the maximum ITD measured with low frequency tone pips was over 320 µs. A spherical head model underestimates ITD magnitude under normal conditions, but closely approximates values when the pinnae were removed. Interaural level differences (ILDs) strongly depended on location and frequency; maximum ILDs were < 10 dB for frequencies < 4 kHz and were as large as 40 dB for frequencies > 10 kHz. Removal of the pinna reduced the depth and sharpness of spectral notches, altered the acoustical axis, and reduced the acoustical gain, ITDs, and ILDs; however, spectral shape features and acoustical gain were not completely eliminated, suggesting a substantial contribution of the head and torso in altering the sounds present at the tympanic membrane. PMID:25051197

Glottal volume velocity waveform characteristics in subjects with and without vocal training, related to gender, sound intensity, fundamental frequency, and age.

PubMed

Sulter, A M; Wit, H P

1996-11-01

Glottal volume velocity waveform characteristics of 224 subjects, categorized in four groups according to gender and vocal training, were determined, and their relations to sound-pressure level, fundamental frequency, intra-oral pressure, and age were analyzed. Subjects phonated at three intensity conditions. The glottal volume velocity waveforms were obtained by inverse filtering the oral flow. Glottal volume velocity waveforms were parameterized with flow-based (minimum flow, ac flow, average flow, maximum flow declination rate) and time-based parameters (closed quotient, closing quotient, speed quotient), as well as with derived parameters (vocal efficiency and glottal resistance). Higher sound-pressure levels, intra-oral pressures, and flow-parameter values (ac flow, maximum flow declination rate) were observed, when compared with previous investigations. These higher values might be the result of the specific phonation tasks (stressed /ae/ vowel in a word and a sentence) or filtering processes. Few statistically significant (p < 0.01) differences in parameters were found between untrained and trained subjects [the maximum flow declination rate and the closing quotient were higher in trained women (p < 0.001), and the speed quotient was higher in trained men (p < 0.005)]. Several statistically significant parameter differences were found between men and women [minimum flow, ac flow, average flow, maximum flow declination rate, closing quotient, glottal resistance (p < 0.001), and closed quotient (p < 0.005)]. Significant effects of intensity condition were observed on ac flow, maximum flow declination rate, closing quotient, and vocal efficiency in women (p < 0.005), and on minimum flow, ac flow, average flow, maximum flow declination rate, closed quotient, and vocal efficiency in men (p < 0.01).

Drilling and operational sounds from an oil production island in the ice-covered Beaufort sea.

PubMed

Blackwell, Susanna B; Greene, Charles R; Richardson, W John

2004-11-01

Recordings of sounds underwater and in air, and of iceborne vibrations, were obtained at Northstar Island, an artificial gravel island in the Beaufort Sea near Prudhoe Bay (Alaska). The aim was to document the levels, characteristics, and range dependence of sounds and vibrations produced by drilling and oil production during the winter, when the island was surrounded by shore-fast ice. Drilling produced the highest underwater broadband (10-10,000 Hz) levels (maximum= 124 dB re: 1 microPa at 1 km), and mainly affected 700-1400 Hz frequencies. In contrast, drilling did not increase broadband levels in air or ice relative to levels during other island activities. Production did not increase broadband levels for any of the sensors. In all media, broadband levels decreased by approximately 20 dB/tenfold change in distance. Background levels underwater were reached by 9.4 km during drilling and 3-4 km without. In the air and ice, background levels were reached 5-10 km and 2-10 km from Northstar, respectively, depending on the wind but irrespective of drilling. A comparison of the recorded sounds with harbor and ringed seal audiograms showed that Northstar sounds were probably audible to seals, at least intermittently, out to approximately 1.5 km in water and approximately 5 km in air.

Assessment of Occupational Noise Exposure among Groundskeepers in North Carolina Public Universities

PubMed Central

Balanay, Jo Anne G.; Kearney, Gregory D.; Mannarino, Adam J.

2016-01-01

Groundskeepers may have increased risk to noise-induced hearing loss due to the performance of excessively noisy tasks. This study assessed the exposure of groundskeepers to noise in multiple universities and determined the association between noise exposure and variables (ie, university, month, tool used). Personal noise exposures were monitored during the work shift using noise dosimetry. A sound level meter was used to measure the maximum sound pressure levels from groundskeeping equipment. The mean Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH) time-weighted average (TWA) noise exposures were 83.0 ± 9.6 and 88.0 ± 6.7 dBA, respectively. About 52% of the OSHA TWAs and 77% of the NIOSH TWAs exceeded 85 dBA. Riding mower use was associated with high TWA noise exposures and with having OSHA TWAs exceeding 85 and 90 dBA. The maximum sound pressure levels of equipment and tools measured ranged from 76 to 109 dBA, 82% of which were >85 dBA. These findings support that groundskeepers have excessive noise exposures, which may be effectively reduced through careful scheduling of the use of noisy equipment/tools. PMID:27330303

Development and Testing of a High Level Axial Array Duct Sound Source for the NASA Flow Impedance Test Facility

NASA Technical Reports Server (NTRS)

Johnson, Marty E.; Fuller, Chris R.; Jones, Michael G. (Technical Monitor)

2000-01-01

In this report both a frequency domain method for creating high level harmonic excitation and a time domain inverse method for creating large pulses in a duct are developed. To create controllable, high level sound an axial array of six JBL-2485 compression drivers was used. The pressure downstream is considered as input voltages to the sources filtered by the natural dynamics of the sources and the duct. It is shown that this dynamic behavior can be compensated for by filtering the inputs such that both time delays and phase changes are taken into account. The methods developed maximize the sound output while (i) keeping within the power constraints of the sources and (ii) maintaining a suitable level of reproduction accuracy. Harmonic excitation pressure levels of over 155dB were created experimentally over a wide frequency range (1000-4000Hz). For pulse excitation there is a tradeoff between accuracy of reproduction and sound level achieved. However, the accurate reproduction of a pulse with a maximum pressure level over 6500Pa was achieved experimentally. It was also shown that the throat connecting the driver to the duct makes it difficult to inject sound just below the cut-on of each acoustic mode (pre cut-on loading effect).

Mapping sound intensities by seating position in a university concert band: A risk of hearing loss, temporary threshold shifts, and comparisons with standards of OSHA and NIOSH

NASA Astrophysics Data System (ADS)

Holland, Nicholas Vedder, III

Exposure to loud sounds is one of the leading causes of hearing loss in the United States. The purpose of the current research was to measure the sound pressure levels generated within a university concert band and determine if those levels exceeded permissible sound limits for exposure according to criteria set by the Occupational Safety and Health Administration (OSHA) and the National Institute of Occupational Safety and Health (NIOSH). Time-weighted averages (TWA) were obtained via a dosimeter during six rehearsals for nine members of the ensemble (plus the conductor), who were seated in frontal proximity to "instruments of power" (trumpets, trombones, and percussion; (Backus, 1977). Subjects received audiometer tests prior to and after each rehearsal to determine any temporary threshold shifts (TTS). Single sample t tests were calculated to compare TWA means and the maximum sound intensity exposures set by OSHA and NIOSH. Correlations were calculated between TWAs and TTSs, as well as TTSs and the number of semesters subjects reported being seated in proximity to instruments of power. The TWA-OSHA mean of 90.2 dBA was not significantly greater than the specified OSHA maximum standard of 90.0 dBA (p > .05). The TWA-NIOSH mean of 93.1 dBA was, however, significantly greater than the NIOSH specified maximum standard of 85.0 dBA (p < .05). The correlation between TWAs and TTSs was considered weak (r = .21 for OSHA, r = .20 for NIOSH); the correlation between TTSs and semesters of proximity to instruments of power was also considered weak (r = .13). TWAs cumulatively exceeded both association's sound exposure limits at 11 specified locations (nine subjects and both ears of the conductor) throughout the concert band's rehearsals. In addition, hearing acuity, as determined by TTSs, was substantially affected negatively by the intensities produced in the concert band. The researcher concluded that conductors, as well as their performers, must be aware of possible damaging sound intensities in rehearsals or performances.

46 CFR 113.50-15 - Loudspeakers.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... With the vessel underway in normal conditions, the minimum sound pressure levels for broadcasting emergency announcements must be— (1) In interior spaces, 75 dB(A) or, if the background noise level exceeds 75 dB(A), then at least 20 dB(A) above maximum background noise level; and (2) In exterior spaces, 80...

Graded behavioral responses and habituation to sound in the common cuttlefish Sepia officinalis.

PubMed

Samson, Julia E; Mooney, T Aran; Gussekloo, Sander W S; Hanlon, Roger T

2014-12-15

Sound is a widely available and vital cue in aquatic environments, yet most bioacoustic research has focused on marine vertebrates, leaving sound detection in invertebrates poorly understood. Cephalopods are an ecologically key taxon that likely use sound and may be impacted by increasing anthropogenic ocean noise, but little is known regarding their behavioral responses or adaptations to sound stimuli. These experiments identify the acoustic range and levels that elicit a wide range of secondary defense behaviors such as inking, jetting and rapid coloration change. Secondarily, it was found that cuttlefish habituate to certain sound stimuli. The present study examined the behavioral responses of 22 cuttlefish (Sepia officinalis) to pure-tone pips ranging from 80 to 1000 Hz with sound pressure levels of 85-188 dB re. 1 μPa rms and particle accelerations of 0-17.1 m s(-2). Cuttlefish escape responses (inking, jetting) were observed between frequencies of 80 and 300 Hz and at sound levels above 140 dB re. 1 μPa rms and 0.01 m s(-2) (0.74 m s(-2) for inking responses). Body patterning changes and fin movements were observed at all frequencies and sound levels. Response intensity was dependent upon stimulus amplitude and frequency, suggesting that cuttlefish also possess loudness perception with a maximum sensitivity around 150 Hz. Cuttlefish habituated to repeated 200 Hz tone pips, at two sound intensities. Total response inhibition was not reached, however, and a basal response remained present in most animals. The graded responses provide a loudness sensitivity curve and suggest an ecological function for sound use in cephalopods. © 2014. Published by The Company of Biologists Ltd.

Neural Correlates of Central Inhibition during Physical Fatigue

PubMed Central

Tanaka, Masaaki; Ishii, Akira; Watanabe, Yasuyoshi

2013-01-01

Central inhibition plays a pivotal role in determining physical performance during physical fatigue. Classical conditioning of central inhibition is believed to be associated with the pathophysiology of chronic fatigue. We tried to determine whether classical conditioning of central inhibition can really occur and to clarify the neural mechanisms of central inhibition related to classical conditioning during physical fatigue using magnetoencephalography (MEG). Eight right-handed volunteers participated in this study. We used metronome sounds as conditioned stimuli and maximum handgrip trials as unconditioned stimuli to cause central inhibition. Participants underwent MEG recording during imagery of maximum grips of the right hand guided by metronome sounds for 10 min. Thereafter, fatigue-inducing maximum handgrip trials were performed for 10 min; the metronome sounds were started 5 min after the beginning of the handgrip trials. The next day, neural activities during imagery of maximum grips of the right hand guided by metronome sounds were measured for 10 min. Levels of fatigue sensation and sympathetic nerve activity on the second day were significantly higher relative to those of the first day. Equivalent current dipoles (ECDs) in the posterior cingulated cortex (PCC), with latencies of approximately 460 ms, were observed in all the participants on the second day, although ECDs were not identified in any of the participants on the first day. We demonstrated that classical conditioning of central inhibition can occur and that the PCC is involved in the neural substrates of central inhibition related to classical conditioning during physical fatigue. PMID:23923034

Long-Term Impairment of Sound Processing in the Auditory Midbrain by Daily Short-Term Exposure to Moderate Noise.

PubMed

Cheng, Liang; Wang, Shao-Hui; Peng, Kang; Liao, Xiao-Mei

2017-01-01

Most citizen people are exposed daily to environmental noise at moderate levels with a short duration. The aim of the present study was to determine the effects of daily short-term exposure to moderate noise on sound level processing in the auditory midbrain. Sound processing properties of auditory midbrain neurons were recorded in anesthetized mice exposed to moderate noise (80 dB SPL, 2 h/d for 6 weeks) and were compared with those from age-matched controls. Neurons in exposed mice had a higher minimum threshold and maximum response intensity, a longer first spike latency, and a higher slope and narrower dynamic range for rate level function. However, these observed changes were greater in neurons with the best frequency within the noise exposure frequency range compared with those outside the frequency range. These sound processing properties also remained abnormal after a 12-week period of recovery in a quiet laboratory environment after completion of noise exposure. In conclusion, even daily short-term exposure to moderate noise can cause long-term impairment of sound level processing in a frequency-specific manner in auditory midbrain neurons.

Long-Term Impairment of Sound Processing in the Auditory Midbrain by Daily Short-Term Exposure to Moderate Noise

PubMed Central

Cheng, Liang; Wang, Shao-Hui; Peng, Kang

2017-01-01

Most citizen people are exposed daily to environmental noise at moderate levels with a short duration. The aim of the present study was to determine the effects of daily short-term exposure to moderate noise on sound level processing in the auditory midbrain. Sound processing properties of auditory midbrain neurons were recorded in anesthetized mice exposed to moderate noise (80 dB SPL, 2 h/d for 6 weeks) and were compared with those from age-matched controls. Neurons in exposed mice had a higher minimum threshold and maximum response intensity, a longer first spike latency, and a higher slope and narrower dynamic range for rate level function. However, these observed changes were greater in neurons with the best frequency within the noise exposure frequency range compared with those outside the frequency range. These sound processing properties also remained abnormal after a 12-week period of recovery in a quiet laboratory environment after completion of noise exposure. In conclusion, even daily short-term exposure to moderate noise can cause long-term impairment of sound level processing in a frequency-specific manner in auditory midbrain neurons. PMID:28589040

Psycho-Physiological Responses by Listening to Some Sounds from Our Daily Life

NASA Astrophysics Data System (ADS)

Sakamoto, H.; Hayashi, F.; Tsujikawa, M.; Sugiura, S.

1997-08-01

This study was made to clarify the relationship between mode of identification, mode of emotion and physiological response to noise. Twenty-six subjects, young females, listened to six different daily sounds for 150 s through head phones. The level of sound was 60-61LAcq. The pulse wave and blood pressure were observed, and pulse wave interval, wave height and maximum and minimum blood pressures were measured. Measurements were taken twice once 30 s before listening and again during the final 30 s of listening. The ratio of the latter value to the former value was used as the index for the evaluation of change. Immediately after the listening session, identification of the sound source and emotional response were surveyed via a questionnaire and the sounds were judged as related to comfort or discomfort. In the case of incorrect identification, physiological functions were not seen to change significantly. However, in the case of correct identification, maximum and minimum blood pressures were significantly increased form the pre-listening values. The physiological functions of the discomfort group did not change significantly. In the comfort group, wave height was decreased and blood pressure was significantly elevated.

Indoor Noise Loading in Residential Prefabricated Buildings

NASA Astrophysics Data System (ADS)

Kraus, Michal; Juhásová Šenitková, Ingrid

2017-10-01

Quality on indoor environment is among others also defined by an acoustic comfort and noise emissions. The indoor noise loading in the residential prefabricated buildings is specific problem related to structural design of these buildings. Problems with noise level of sanitary systems are mostly associated with hydraulic shock such as water distribution and sewage drainage. Another very common cause of excessive noise is also flushing the toilet or water fall on enamelled steel (bath or shower). This paper aims to analyse the acoustic properties in the residential prefabricated buildings. Sanitary core of the assessed apartment is in original condition without any alterations. The sanitary core is based on a formica (high-pressure laminate). The study discusses the maximum sound levels in the three assessed rooms for the three different noise sources. The values of maximum noise level are measured for the corridor, bedroom and living room. Sources of noise are common activities relating to the operation of sanitary core - the toilet flush in the toilet, falling water from the shower in the bathroom and the water falling on the bottom of the kitchen sink in the kitchen. Other sources of noise are eliminated or minimized during the experiment. The digital sound level meter Testo 815 is used for measurements. The measured values of maximum sound level LA,max [dB] are adjusted by the correction coefficient. The obtained values are compared with the hygienic limits for day and night period. Night hygienic limit (30 dB) is exceeded in all the rooms for all noise sources. This limit is exceeded from 17 to 73%. The values in the bedroom and the living room meet the daily hygienic limit (40 dB). The daily limit is exceeded only in the corridor. The highest values of noise are identified for the toilet flushing.

Multiple-Pulse Sounds and Seals: Results of a Harbor Seal (Phoca vitulina) Telemetry Study During Wind Farm Construction.

PubMed

Hastie, Gordon D; Russell, Debbie J F; McConnell, Bernie; Thompson, Dave; Janik, Vincent M

2016-01-01

Offshore construction and survey techniques can produce pulsed sounds with a high sound pressure level. In coastal waters, the areas in which they are produced are often also used by seals, potentially resulting in auditory damage or behavioral avoidance. Here, we describe a study on harbor seals during a wind farm installation off southeast England. The study used GPS/global system for mobile communication tags on 23 harbor seals that provided distribution and activity data; the closest range of individual seals to piling varied from 6.65 to 46.1 km. Furthermore, the maximum predicted received levels (RLs) at individual seals varied between 146.9 and 169.4 dB re 1 μPa peak to peak.

Effects of sound exposure on the growth and intracellular macromolecular synthesis of E. coli k-12

PubMed Central

Zhang, Yongzhu; Wu, Ying

2016-01-01

Microbes, as one of the primary producers of the biosphere, play an important role in ecosystems. Exploring the mechanism of adaptation and resistance of microbial population to various environmental factors has come into focus in the fields of modern microbial ecology and molecular ecology. However, facing the increasingly serious problem of acoustic pollution, very few efforts have been put forth into studying the relation of single cell organisms and sound field exposure. Herein, we studied the biological effects of sound exposure on the growth of E. coli K-12 with different acoustic parameters. The effects of sound exposure on the intracellular macromolecular synthesis and cellular morphology of E. coli K-12 were also analyzed and discussed. Experimental results indicated that E. coli K-12 exposed to sound waves owned a higher biomass and a faster specific growth rate compared to the control group. Also, the average length of E. coli K-12 cells increased more than 27.26%. The maximum biomass and maximum specific growth rate of the stimulation group by 8000 Hz, 80dB sound wave was about 1.7 times and 2.5 times that of the control group, respectively. Moreover, it was observed that E. coli K-12 can respond rapidly to sound stress at both the transcriptional and posttranscriptional levels by promoting the synthesis of intracellular RNA and total protein. Some potential mechanisms may be involved in the responses of bacterial cells to sound stress. PMID:27077011

Effects of sound exposure on the growth and intracellular macromolecular synthesis of E. coli k-12.

PubMed

Gu, Shaobin; Zhang, Yongzhu; Wu, Ying

2016-01-01

Microbes, as one of the primary producers of the biosphere, play an important role in ecosystems. Exploring the mechanism of adaptation and resistance of microbial population to various environmental factors has come into focus in the fields of modern microbial ecology and molecular ecology. However, facing the increasingly serious problem of acoustic pollution, very few efforts have been put forth into studying the relation of single cell organisms and sound field exposure. Herein, we studied the biological effects of sound exposure on the growth of E. coli K-12 with different acoustic parameters. The effects of sound exposure on the intracellular macromolecular synthesis and cellular morphology of E. coli K-12 were also analyzed and discussed. Experimental results indicated that E. coli K-12 exposed to sound waves owned a higher biomass and a faster specific growth rate compared to the control group. Also, the average length of E. coli K-12 cells increased more than 27.26%. The maximum biomass and maximum specific growth rate of the stimulation group by 8000 Hz, 80dB sound wave was about 1.7 times and 2.5 times that of the control group, respectively. Moreover, it was observed that E. coli K-12 can respond rapidly to sound stress at both the transcriptional and posttranscriptional levels by promoting the synthesis of intracellular RNA and total protein. Some potential mechanisms may be involved in the responses of bacterial cells to sound stress.

A three-dimensional integrated nanogenerator for effectively harvesting sound energy from the environment

NASA Astrophysics Data System (ADS)

Liu, Jinmei; Cui, Nuanyang; Gu, Long; Chen, Xiaobo; Bai, Suo; Zheng, Youbin; Hu, Caixia; Qin, Yong

2016-02-01

An integrated triboelectric nanogenerator (ITNG) with a three-dimensional structure benefiting sound propagation and adsorption is demonstrated to more effectively harvest sound energy with improved output performance. With different multifunctional integrated layers working harmonically, it could generate a short-circuit current up to 2.1 mA, an open-circuit voltage up to 232 V and the maximum charging rate can reach 453 μC s-1 for a 1 mF capacitor, which are 4.6 times, 2.6 times and 7.4 times the highest reported values, respectively. Further study shows that the ITNG works well under sound in a wide range of sound intensity levels (SILs) and frequencies, and its output is sensitive to the SIL and frequency of the sound, which reveals that the ITNG can act as a self-powered active sensor for real-time noise surveillance and health care. Moreover, this generator can be used to directly power the Fe(OH)3 sol electrophoresis and shows great potential as a wireless power supply in the electrochemical industry.An integrated triboelectric nanogenerator (ITNG) with a three-dimensional structure benefiting sound propagation and adsorption is demonstrated to more effectively harvest sound energy with improved output performance. With different multifunctional integrated layers working harmonically, it could generate a short-circuit current up to 2.1 mA, an open-circuit voltage up to 232 V and the maximum charging rate can reach 453 μC s-1 for a 1 mF capacitor, which are 4.6 times, 2.6 times and 7.4 times the highest reported values, respectively. Further study shows that the ITNG works well under sound in a wide range of sound intensity levels (SILs) and frequencies, and its output is sensitive to the SIL and frequency of the sound, which reveals that the ITNG can act as a self-powered active sensor for real-time noise surveillance and health care. Moreover, this generator can be used to directly power the Fe(OH)3 sol electrophoresis and shows great potential as a wireless power supply in the electrochemical industry. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr09087c

Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

NASA Astrophysics Data System (ADS)

Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

2016-01-01

A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates over the evanescent sound field because of broadening of the wavenumber spectrum. Therefore, we calculated the optimum distribution of the particle velocity on the vibrating plate to reduce the broadening of the wavenumber spectrum. We focused on a window function that is utilized in the field of signal analysis for reducing the broadening of the frequency spectrum. The optimization calculation is necessary for the design of window function suitable for suppressing sound radiation and securing a spatial area for data communication. In addition, a wide frequency bandwidth is required to increase the data transmission speed. Therefore, we investigated a suitable method for calculating the sound pressure level at the far field to confirm the variation of the distribution of sound pressure level determined on the basis of the window shape and frequency. The distribution of the sound pressure level at a finite distance was in good agreement with that obtained at an infinite far field under the condition generating the evanescent sound field. Consequently, the window function was optimized by the method used to calculate the distribution of the sound pressure level at an infinite far field using the wavenumber spectrum on the vibrating plate. According to the result of comparing the distributions of the sound pressure level in the cases with and without the window function, it was confirmed that the area whose sound pressure level was reduced from the maximum level to -50 dB was extended. Additionally, we designed a sound insulator so as to realize a similar distribution of the particle velocity to that obtained using the optimized window function. Sound radiation was suppressed using a sound insulator put above the vibrating surface in the simulation using the three-dimensional finite element method. On the basis of this finding, it was suggested that near-field acoustic communication which suppressed sound radiation can be realized by applying the optimized window function to the particle velocity field.

Sound from a Two-Blade Propeller at Supersonic Tip Speeds

NASA Technical Reports Server (NTRS)

Hubbard, Harvey H; Lassiter, Leslie W

1952-01-01

Report presents the results of sound measurements at static conditions made for a two-blade 47-inch-diameter propeller in the tip Mach number range 0.75 to 1.30. For comparison, spectrums have been obtained at both subsonic and supersonic tip speeds. In addition, the measured data are compared with calculations by the theory of Gutin which has previously been found adequate for predicting the sound at subsonic tip speeds. Curves are presented from which the maximum over-all noise levels in free space may be estimated if the power, tip Mach number, and distance are known.

A descriptive study of noise in the neonatal intensive care unit: ambient levels and perceptions of contributing factors.

PubMed

Darcy, Ashley E; Hancock, Lauren E; Ware, Emily J

2008-10-01

To examine the baseline acoustic environment in several mid-Atlantic region neonatal intensive care units (NICUs) and investigate the perceived factors contributing to noise levels in these NICUs. Quantitative data were collected from 3 urban, mid-Atlantic level IIIB and level IIIC NICUs. Qualitative data were collected via interview from 2 RNs employed in each of the study NICUs. This was an exploratory descriptive study utilizing a mixed-methods approach. A quantitative method was used for sound-level data collection, and a qualitative method was utilized during interviews with nurses to examine perceptions of factors contributing to noise. Ambient sound levels, measured in decibels, were taken at 5-minute intervals over a 2-hour period during both day and night shifts in a central location at each NICU. In addition, nurses were interviewed using a standardized interview questionnaire, and these interviews were then reviewed to determine themes regarding perceived factors contributing to sound levels. Hourly mean sound levels in each NICU ranged from 53.9 dB to 60.6 dB, with no statistically significant difference between noise levels recorded on day shift versus night shift, and no statistically significant difference among sites. Qualitative data showed that nurses' believed day shift to be louder than night shift and many perceived their own NICU as "pretty quiet." Key contributing factors to increased sound levels were stated as monitors or alarms, performing invasive procedures, presence of family, nurses or doctors giving report or rounds, and ringing phones. Noise levels were found to be above the American Academy of Pediatrics-recommended 45-dB level and often louder than the 50-dB level, which should not be exceeded more than 10% of the time. The recommended impulse maximum of 65 dB was also exceeded. Environmental Protection Agency recommendations for hospitals include sound levels no louder than 35 dB on night shift; this standard was also violated. Elevated sound levels need to be addressed in individual NICUs around the country. Further exploratory studies, as well as research regarding effective methods of decreasing sound levels in the NICU environment, are necessary. NICUs can implement behavioral and structural changes that can decrease the sound levels in the NICU environment and decrease the potential for exposure of patients to the harmful physiological effects of increased sound levels.

A descriptive study of noise in the neonatal intensive care unit. Ambient levels and perceptions of contributing factors.

PubMed

Darcy, Ashley E; Hancock, Lauren E; Ware, Emily J

2008-06-01

To examine the baseline acoustic environment in several mid-Atlantic region neonatal intensive care units (NICUs) and investigate the perceived factors contributing to noise levels in these NICUs. Quantitative data were collected from 3 urban, mid-Atlantic level IIIB and level IIIC NICUs. Qualitative data were collected via interview from 2 RNs employed in each of the study NICUs. This was an exploratory descriptive study utilizing a mixed-methods approach. A quantitative method was used for sound-level data collection, and a qualitative method was utilized during interviews with nurses to examine perceptions of factors contributing to noise. Ambient sound levels, measured in decibels, were taken at 5-minute intervals over a 2-hour period during both day and night shifts in a central location at each NICU. In addition, nurses were interviewed using a standardized interview questionnaire, and these interviews were then reviewed to determine themes regarding perceived factors contributing to sound levels. Hourly mean sound levels in each NICU ranged from 53.9 dB to 60.6 dB, with no statistically significant difference between noise levels recorded on day shift versus night shift, and no statistically significant difference among sites. Qualitative data showed that nurses' believed day shift to be louder than night shift and many perceived their own NICU as "pretty quiet." Key contributing factors to increased sound levels were stated as monitors or alarms, performing invasive procedures, presence of family, nurses or doctors giving report or rounds, and ringing phones. Noise levels were found to be above the American Academy of Pediatrics--recommended 45-dB level and often louder than the 50-dB level, which should not be exceeded more than 10% of the time. The recommended impulse maximum of 65 dB was also exceeded. Environmental Protection Agency recommendations for hospitals include sound levels no louder than 35 dB on night shift; this standard was also violated. Elevated sound levels need to be addressed in individual NICUs around the country. Further exploratory studies, as well as research regarding effective methods of decreasing sound levels in the NICU environment, are necessary. NICUs can implement behavioral and structural changes that can decrease the sound levels in the NICU environment and decrease the potential for exposure of patients to the harmful physiological effects of increased sound levels.

Where is the level of neutral buoyancy for deep convection?

NASA Astrophysics Data System (ADS)

Takahashi, Hanii; Luo, Zhengzhao

2012-08-01

This study revisits an old concept in meteorology - level of neutral buoyancy (LNB). The classic definition of LNB is derived from the parcel theory and can be estimated from the ambient sounding (LNB_sounding) without having to observe any actual convective cloud development. In reality, however, convection interacts with the environment in complicated ways; it will eventually manage to find its own effective LNB and manifests it through detraining masses and developing anvils (LNB_observation). This study conducts a near-global survey of LNB_observation for tropical deep convection using CloudSat data and makes comparison with the corresponding LNB_sounding. The principal findings are as follows: First, although LNB_sounding provides a reasonable upper bound for convective development, correlation between LNB_sounding and LNB_observation is low suggesting that ambient sounding contains limited information for accurately predicting the actual LNB. Second, maximum mass outflow is located more than 3 km lower than LNB_sounding. Hence, from convective transport perspective, LNB_sounding is a significant overestimate of the “destination” height level of the detrained mass. Third, LNB_observation is consistently higher over land than over ocean, although LNB_sounding is similar between land and ocean. This difference is likely related to the contrasts in convective strength and environment between land and ocean. Finally, we estimate the bulk entrainment rates associated with the observed deep convection, which can serve as an observational basis for adjusting GCM cumulus parameterization.

Sound levels in conservative dentistry and endodontics clinic

PubMed Central

Dutta, Arindam; Mala, Kundabala; Acharya, Shashi Rashmi

2013-01-01

Aim: To evaluate the sound levels generated in dental clinics of conservative dentistry and endodontics. Material and Methods: A decibel-meter with digital readout was used to measure sound levels at different time intervals at the chairside and at the center of the clinic. Minimum and maximum readings during a 3 min interval were recorded. Results: In the post-graduate (PG) clinic, there was significant difference in noise levels between the chairside (66-81 dB[A]) and the center of the clinic (66-67 dB[A]) at certain times. In the under graduate (UG) clinic, noise levels with suction and either high/slow speed handpieces (67-80 dB[A]) were significantly higher than the center of clinic. Suction alone in the UG clinic (63-75 dB[A]) was significantly quieter than in the PG clinic (69-79 dB[A]). Conclusions: (1) Mean sound levels in the working clinics ranged from 63.0 dB[A] to 81.5 dB[A]. These are within the recommended range for dental equipment. (2) With suction and either low/high speed handpiece combination, the PG clinic was significantly noisier than the UG clinic at several time periods. PMID:23716962

Acoustic Performance of a Real-Time Three-Dimensional Sound-Reproduction System

NASA Technical Reports Server (NTRS)

Faller, Kenneth J., II; Rizzi, Stephen A.; Aumann, Aric R.

2013-01-01

The Exterior Effects Room (EER) is a 39-seat auditorium at the NASA Langley Research Center and was built to support psychoacoustic studies of aircraft community noise. The EER has a real-time simulation environment which includes a three-dimensional sound-reproduction system. This system requires real-time application of equalization filters to compensate for spectral coloration of the sound reproduction due to installation and room effects. This paper describes the efforts taken to develop the equalization filters for use in the real-time sound-reproduction system and the subsequent analysis of the system s acoustic performance. The acoustic performance of the compensated and uncompensated sound-reproduction system is assessed for its crossover performance, its performance under stationary and dynamic conditions, the maximum spatialized sound pressure level it can produce from a single virtual source, and for the spatial uniformity of a generated sound field. Additionally, application examples are given to illustrate the compensated sound-reproduction system performance using recorded aircraft flyovers

Noise in the operating rooms of Greek hospitals.

PubMed

Tsiou, Chrisoula; Efthymiatos, Gerasimos; Katostaras, Theophanis

2008-02-01

This study is an evaluation of the problem of noise pollution in operating rooms. The high sound pressure level of noise in the operating theatre has a negative impact on communication between operating room personnel. The research took place at nine Greek public hospitals with more than 400 beds. The objective evaluation consisted of sound pressure level measurements in terms of L(eq), as well as peak sound pressure levels in recordings during 43 surgeries in order to identify sources of noise. The subjective evaluation consisted of a questionnaire answered by 684 operating room personnel. The views of operating room personnel were studied using Pearson's X(2) Test and Fisher's Exact Test (SPSS Version 10.00), a t-test comparison was made of mean sound pressure levels, and the relationship of measurement duration and sound pressure level was examined using linear regression analysis (SPSS Version 13.00). The sound pressure levels of noise per operation and the sources of noise varied. The maximum measured level of noise during the main procedure of an operation was measured at L(eq)=71.9 dB(A), L(1)=84.7 dB(A), L(10)=76.2 dB(A), and L(99)=56.7 dB(A). The hospital building, machinery, tools, and people in the operating room were the main noise factors. In order to eliminate excess noise in the operating room it may be necessary to adopt a multidisciplinary approach. An improvement in environment (background noise levels), the implementation of effective standards, and the focusing of the surgical team on noise matters are considered necessary changes.

Traffic Noise Assessment at Residential Areas in Skudai, Johor

NASA Astrophysics Data System (ADS)

Sulaiman, F. S.; Darus, N.; Mashros, N.; Haron, Z.; Yahya, K.

2018-03-01

Vehicles passing by on roadways in residential areas may produce unpleasant traffic noise that affects the residents. This paper presents the traffic noise assessment of three selected residential areas located in Skudai, Johor. The objectives of this study are to evaluate traffic characteristics at selected residential areas, determine related noise indices, and assess impact of traffic noise. Traffic characteristics such as daily traffic volume and vehicle speed were evaluated using automatic traffic counter (ATC). Meanwhile, noise indices like equivalent continuous sound pressure level (LAeq), noise level exceeded 10% (L10) and 90% (L90) of measurement time were determined using sound level meter (SLM). Besides that, traffic noise index (TNI) and noise pollution level (LNP) were calculated based on the measured noise indices. The results showed an increase in noise level of 60 to 70 dBA maximum due to increase in traffic volume. There was also a significant change in noise level of more than 70 dBA even though average vehicle speed did not vary significantly. Nevertheless, LAeq, TNI, and LNP values for all sites during daytime were lower than the maximum recommended levels. Thus, residents in the three studied areas were not affected in terms of quality of life and health.

Characterizing noise and perceived work environment in a neurological intensive care unit.

PubMed

Ryherd, Erica E; Waye, Kerstin Persson; Ljungkvist, Linda

2008-02-01

The hospital sound environment is complex. Alarms, medical equipment, activities, and ventilation generate noise that may present occupational problems as well as hinder recovery among patients. In this study, sound measurements and occupant evaluations were conducted in a neurological intensive care unit. Staff completed questionnaires regarding psychological and physiological reactions to the sound environment. A-weighted equivalent, minimum, and maximum (L(Aeq),L(AFMin),L(AFMax)) and C-weighted peak (L(CPeak)) sound pressure levels were measured over five days at patient and staff locations. Acoustical descriptors that may be explored further were investigated, including level distributions, restorative periods, and spectral content. Measurements near the patients showed average L(Aeq) values of 53-58 dB. The mean length of restorative periods (L(Aeq) below 50 dB for more than 5 min) was 9 and 13 min for day and night, respectively. Ninety percent of the time, the L(AFMax) levels exceeded 50 dB and L(CPeak) exceeded 70 dB. Dosimeters worn by the staff revealed higher noise levels. Personnel perceived the noise as contributing to stress symptoms. Compared to the majority of previous studies, this study provides a more thorough description of intensive care noise and aids in understanding how the sound environment may be disruptive to occupants.

[Verified maximum admissible intensity (MAI) values for the ultrasonic noise in work environment].

PubMed

Pawlaczyk-Łuszcyńska, M; Koton, J; Augustyńska, D; Sliwińska-Kowalska, M; Kameduła, M

2001-01-01

The measurement methods and occupational exposure limits for ultrasonic noise (airborne ultrasound) are described. Typical sources of ultrasonic noise and sound pressure levels measured at workplaces are discussed. The verified Polish regulations on maximum admissible intensity (MAI) values for ultrasonic noise in the work environment and proposals of exposure limits for workers at particular risk (i.e. pregnant women and juveniles) are presented.

Investigations of ionospheric sporadic Es layer using oblique sounding method

NASA Astrophysics Data System (ADS)

Minullin, R.

The characteristics of Es layer have been studied using oblique sounding at 28 radiolines at the frequencies of 34 -- 73 MHz at the transmission paths 400 -- 1600 km long during 30 years. Reflections from Es layer with a few hours duration were observed. The amplitude of the reflected signal reached 1000 μ V with the registration threshold 0,1 μ V. The borderlines between reflected and scattered signals were observed as sharp curves in 60 -- 100 s range on the distributions of duration of reflected signals for decameter waves. The duration of continuous Es reflections were decreased upon amplification of oblique sounding frequency. The distributions of duration of reflected signals for meter waves showed sharp curves in the range 200 -- 300 s, representing borderlines between signals reflected from meteoric traces and from Es layer. The filling coefficient for the oblique sounding as well as the Es layer emersion probability for the vertical sounding were shown to undergo daily, seasonal and periodic variations. The daily variations of the filling coefficient of Es signals showed clear-cut maximums at 10 -- 12 and 18 -- 20 hours and minimum at 4 -- 6 hours at all paths in summer time and the maximum at 12 -- 14 hours in winter time. The values of the filling coefficient for Es layer declined with the increase of oblique sounding frequency. The minimal values of the filling coefficient were observed in winter and early spring, while the maximal values were observed from May to August. Provided that the averaged filling coefficient is equal to one in summer, it reaches the level 0,25 in equinox and does not exceed the level 0,12 in winter as evident by the of oblique sounding. The filling coefficient relation to the value of the voltage detection threshold was approximated by power-mode law. The filling coefficients for summer period showed exponential relation with equivalent sounding frequencies. The experimental evidence was generalized in an analytical model. Using this model the averaged Es layer filling coefficients for particular season of the year can be forecasted in case of given sounding frequency, path length, and voltage threshold.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Efroymson, Rebecca Ann; Hargrove, William Walter; Suter, Glenn

A multi-stressor risk assessment was conducted at Yuma Proving Ground, Arizona, as a demonstration of the Military Ecological Risk Assessment Framework. The focus of the assessment was a testing program at Cibola Range, which involved an Apache Longbow helicopter firing Hellfire missiles at moving targets, M60-A1 tanks. This paper focuses on the wildlife risk assessment for the helicopter overflight. The primary stressors were sound and the view of the aircraft. Exposure to desert mule deer (Odocoileus hemionus crooki) was quantified using Air Force sound contour programs NOISEMAP and MR_NMAP, which gave very different results. Slant distance from helicopters to deermore » was also used as a measure of exposure that integrated risk from sound and view of the aircraft. Exposure-response models for the characterization of effects consisted of behavioral thresholds in sound exposure level or maximum sound level units or slant distance. Available sound thresholds were limited for desert mule deer, but a distribution of slant-distance thresholds was available for ungulates. The risk characterization used a weight-of-evidence approach and concluded that risk to mule deer behavior from the Apache overflight is uncertain, but that no risk to mule deer abundance and reproduction is expected.« less

Exposure to impulse noise at an explosives company: a case study.

PubMed

Kulik, Aleksandra; Malinowska-Borowska, Jolanta

2018-02-15

Impulse noise encountered in workplaces is a threat to hearing. The aim of this study was to assess the occupational exposure to impulse noise produced by detonation of dynamite on the premises of an explosives company. Test points were located on the blast test area (inside and outside the bunker) and in work buildings across the site. Noise propagation measurement was performed during 130 blast tests at nine measurement points. At every point, at least 10 separate measurements of A-weighted equivalent sound pressure level (L A eq ), maximum A-weighted sound pressure level (L A max ) and C-weighted peak sound pressure level (L C peak ) were made. Noise recorded in the blast test area exceeded occupational exposure limits (OELs). Noise levels measured in buildings did not exceed OELs. Results of the survey showed that for 62% of respondents, impulse noise causes difficulties in performing work. The most commonly reported symptoms include headaches, nervousness and irritability.

[Industrial sound spectrum entailing noise-induced occupational hearing loss in Iasi industry].

PubMed

Carp, Cristina Maria; Costinescu, V N

2011-01-01

In European Union every day millions of employees are exposed to noise at work and the risk this can entail. this study presents the sound spectrum in Iasi heavy industry: metal foundries industry, punching and embossing of metal sheets, cold and hot metal processing. it was used a type 2 Sound Level Meter (SLM) and the considered value was the average value over 10 test values in 10 consecutive days for each octave band in common audible frequency range. It is obviously that the large values of sound intensities in the most of frequency octave band exceed maximum admissible and legal values. The study reveals the necessity of hardware, medical and managerial measures in order to reduce the occupational noise and to prevent the hearing acuity damage of the workers.

ANSI Standard: Complying with Background Noise Limits.

ERIC Educational Resources Information Center

Schaffer, Mark E.

2003-01-01

Discusses the new classroom acoustics standard, ANSI Standard S12.60, which specifies maximum sound level limits that are significantly lower than currently typical for classrooms. Addresses guidelines for unducted HVAC systems, ducted single-zone systems, and central VAV or multizone systems. (EV)

Relation of sound intensity and accuracy of localization.

PubMed

Farrimond, T

1989-08-01

Tests were carried out on 17 subjects to determine the accuracy of monaural sound localization when the head is not free to turn toward the sound source. Maximum accuracy of localization for a constant-volume sound source coincided with the position for maximum perceived intensity of the sound in the front quadrant. There was a tendency for sounds to be perceived more often as coming from a position directly toward the ear. That is, for sounds in the front quadrant, errors of localization tended to be predominantly clockwise (i.e., biased toward a line directly facing the ear). Errors for sounds occurring in the rear quadrant tended to be anticlockwise. The pinna's differential effect on sound intensity between front and rear quadrants would assist in identifying the direction of movement of objects, for example an insect, passing the ear.

Recent Enhancements to the NASA Langley Structural Acoustics Loads and Transmission (SALT) Facility

NASA Technical Reports Server (NTRS)

Rizzi, Stephen A.; Cabell, Randolph H.; Allen, Albert R.

2013-01-01

The Structural Acoustics Loads and Transmission (SALT) facility at the NASA Langley Research Center is comprised of an anechoic room and a reverberant room, and may act as a transmission loss suite when test articles are mounted in a window connecting the two rooms. In the latter configuration, the reverberant room acts as the noise source side and the anechoic room as the receiver side. The noise generation system used for qualification testing in the reverberant room was previously shown to achieve a maximum overall sound pressure level of 141 dB. This is considered to be marginally adequate for generating sound pressure levels typically required for launch vehicle payload qualification testing. Recent enhancements to the noise generation system increased the maximum overall sound pressure level to 154 dB, through the use of two airstream modulators coupled to 35 Hz and 160 Hz horns. This paper documents the acoustic performance of the enhanced noise generation system for a variety of relevant test spectra. Additionally, it demonstrates the capability of the SALT facility to conduct transmission loss and absorption testing in accordance with ASTM and ISO standards, respectively. A few examples of test capabilities are shown and include transmission loss testing of simple unstiffened and built up structures and measurement of the diffuse field absorption coefficient of a fibrous acoustic blanket.

[Acoustic conditions in open plan offices - Pilot test results].

PubMed

Mikulski, Witold

The main source of noise in open plan office are conversations. Office work standards in such premises are attained by applying specific acoustic adaptation. This article presents the results of pilot tests and acoustic evaluation of open space rooms. Acoustic properties of 6 open plan office rooms were the subject of the tests. Evaluation parameters, measurement methods and criterial values were adopted according to the following standards: PN-EN ISO 3382- 3:2012, PN-EN ISO 3382-2:2010, PN-B-02151-4:2015-06 and PN-B-02151-3:2015-10. The reverberation time was 0.33- 0.55 s (maximum permissible value in offices - 0.6 s; the criterion was met), sound absorption coefficient in relation to 1 m2 of the room's plan was 0.77-1.58 m2 (minimum permissible value - 1.1 m2; 2 out of 6 rooms met the criterion), distraction distance was 8.5-14 m (maximum permissible value - 5 m; none of the rooms met the criterion), A-weighted sound pressure level of speech at a distance of 4 m was 43.8-54.7 dB (maximum permissible value - 48 dB; 2 out of 6 rooms met the criterion), spatial decay rate of the speech was 1.8-6.3 dB (minimum permissible value - 7 dB; none of the rooms met the criterion). Standard acoustic treatment, containing sound absorbing suspended ceiling, sound absorbing materials on the walls, carpet flooring and sound absorbing workplace barriers, is not sufficient. These rooms require specific advanced acoustic solutions. Med Pr 2016;67(5):653-662. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Sound pressure level in a municipal preschool

PubMed Central

Kemp, Adriana Aparecida Tahara; Delecrode, Camila Ribas; Guida, Heraldo Lorena; Ribeiro, André Knap; Cardoso, Ana Claúdia Vieira

2013-01-01

Summary Aim: To evaluate the sound pressure level to which preschool students are exposed. Method: This was a prospective, quantitative, nonexperimental, and descriptive study. To achieve the aim of the study we used an audio dosimeter. The sound pressure level (SPL) measurements were obtained for 2 age based classrooms. Preschool I and II. The measurements were obtained over 4 days in 8-hour sessions, totaling 1920 minutes. Results: Compared with established standards, the SPL measured ranged from 40.6 dB (A) to 105.8 dB (A). The frequency spectrum of the SPL was concentrated in the frequency range between 500 Hz and 4000 Hz. The older children produced higher SPLs than the younger ones, and the levels varied according to the activity performed. Painting and writing were the quietest activities, while free activities period and games were the noisiest. Conclusion: The SPLs measured at the preschool were higher and exceeded the maximum permitted level according to the reference standards. Therefore, the implementation of actions that aim to minimize the negative impact of noise in this environment is essential. PMID:25992013

Sources and levels of ambient ocean sound near the Antarctic Peninsula.

PubMed

Dziak, Robert P; Bohnenstiehl, DelWayne R; Stafford, Kathleen M; Matsumoto, Haruyoshi; Park, Minkyu; Lee, Won Sang; Fowler, Matt J; Lau, Tai-Kwan; Haxel, Joseph H; Mellinger, David K

2015-01-01

Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (Antarctic Peninsula region) from 2005 to 2009 to record ambient ocean sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the ocean soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapid disintegration also releases significant acoustic energy, equivalent to large-scale geophysical events. Overall ambient sound levels can be as much as ~10-20 dB higher in the open, deep ocean of the Scotia Sea compared to the relatively shallow Bransfield Strait. Noise levels become lowest during the austral winter, as sea-ice cover suppresses wind and wave noise. Ambient noise levels are highest during austral spring and summer, as surface noise, ice cracking and biological activity intensifies. Vocalizations of blue (Balaenoptera musculus) and fin (B. physalus) whales also dominate the long-term spectra records in the 15-28 and 89 Hz bands. Blue whale call energy is a maximum during austral summer-fall in the Drake Passage and Bransfield Strait when ambient noise levels are a maximum and sea-ice cover is a minimum. Fin whale vocalizations were also most common during austral summer-early fall months in both the Bransfield Strait and Scotia Sea. The hydrophone data overall do not show sustained anthropogenic sources (ships and airguns), likely due to low coastal traffic and the typically rough weather and sea conditions of the Southern Ocean.

Sources and Levels of Ambient Ocean Sound near the Antarctic Peninsula

PubMed Central

Dziak, Robert P.; Bohnenstiehl, DelWayne R.; Stafford, Kathleen M.; Matsumoto, Haruyoshi; Park, Minkyu; Lee, Won Sang; Fowler, Matt J.; Lau, Tai-Kwan; Haxel, Joseph H.; Mellinger, David K.

2015-01-01

Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (Antarctic Peninsula region) from 2005 to 2009 to record ambient ocean sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the ocean soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapid disintegration also releases significant acoustic energy, equivalent to large-scale geophysical events. Overall ambient sound levels can be as much as ~10–20 dB higher in the open, deep ocean of the Scotia Sea compared to the relatively shallow Bransfield Strait. Noise levels become lowest during the austral winter, as sea-ice cover suppresses wind and wave noise. Ambient noise levels are highest during austral spring and summer, as surface noise, ice cracking and biological activity intensifies. Vocalizations of blue (Balaenoptera musculus) and fin (B. physalus) whales also dominate the long-term spectra records in the 15–28 and 89 Hz bands. Blue whale call energy is a maximum during austral summer-fall in the Drake Passage and Bransfield Strait when ambient noise levels are a maximum and sea-ice cover is a minimum. Fin whale vocalizations were also most common during austral summer-early fall months in both the Bransfield Strait and Scotia Sea. The hydrophone data overall do not show sustained anthropogenic sources (ships and airguns), likely due to low coastal traffic and the typically rough weather and sea conditions of the Southern Ocean. PMID:25875205

Environment in pediatric wards: light, sound, and temperature.

PubMed

Oliveira, Lia; Gomes, Cláudia; Bacelar Nicolau, Leonor; Ferreira, Luís; Ferreira, Rosário

2015-09-01

The mutual relationship between sleep and disease is well known, becoming more relevant whenever the disease leads to hospitalization. We intend to describe patterns of environmental factors of some pediatric wards, and to verify if these are in line with those recommended. As a secondary aim, we characterize sleep quality during hospitalization. Five pediatric wards of a tertiary-level hospital were included. Light, sound, and temperature were measured and assessed through descriptive statistics. The following recommended values were considered: maximum light 100 Lux, maximum sound 45 dB, and optimal temperature 20-24 °C. A questionnaire was prepared to assess children's sleep, and it was completed by a caregiver. Light values were within the desirable limits for 86% of evaluated time. In all wards, the intensity of sound was much higher than desirable, being above 45 dB during 85% of evaluated time. The temperature was above 24 °C during 78% of total time. Based on 34 answered questionnaires (out of 50 distributed), almost half of the respondents believe that sleep quality and restlessness are worse at the hospital. Most children slept for a longer time at home. Eighteen children awoke more times at the hospital, and those awakenings were mostly attributed to noise. The sound and temperature were higher than recommended. The different values between these wards may be due to different levels of care, but this shows that there are no standard rules on this matter. A worse quality and shorter duration of sleep at hospital were reported. Comprehensive studies are necessary to evaluate the impact of environmental factors on disease recovery. Copyright © 2015 Elsevier B.V. All rights reserved.

Impulse noise generated by starter pistols

PubMed Central

Meinke, Deanna K.; Finan, Donald S.; Soendergaard, Jacob; Flamme, Gregory A.; Murphy, William J.; Lankford, James E.; Stewart, Michael

2015-01-01

Objective This study describes signals generated by .22 and .32 caliber starter pistols in the context of noise-induced hearing loss risk for sports officials and athletes. Design Acoustic comparison of impulses generated from typical .22 and .32 caliber starter pistols firing blanks were made to impulses generated from comparable firearms firing both blanks and live rounds. Acoustic characteristics are described in terms of directionality and distance from the shooter in a simulated outdoor running track. Metrics include peak sound pressure levels (SPL), A-weighted equivalent 8-hour level (LeqA8), and maximum permissible number of individual shots, or maximum permissible exposures (MPE) for the unprotected ear. Results Starter pistols produce peak SPLs above 140 dB. The numbers of MPEs are as few as five for the .22-caliber starter pistol, and somewhat higher (≤25) for the .32-caliber pistol. Conclusion The impulsive sounds produced by starter pistols correspond to MPE numbers that are unacceptably small for unprotected officials and others in the immediate vicinity of the shooter. At the distances included in this study, the risk to athletes appears to be low (when referencing exposure criteria for adults), but the sound associated with the starter pistol will contribute to the athlete’s overall noise exposure. PMID:23373743

Measurement of ground and nearby building vibration and noise induced by trains in a metro depot.

PubMed

Zou, Chao; Wang, Yimin; Wang, Peng; Guo, Jixing

2015-12-01

Metro depots are where subway trains are parked and where maintenance is carried out. They usually occupy the largest ground areas in metro projects. Due to land utilization problems, Chinese cities have begun to develop over-track buildings above metro depots for people's life and work. The frequently moving trains, when going into and out of metro depots, can cause excessive vibration and noise to over-track buildings and adversely affect the living quality of the building occupants. Considering the current need of reliable experimental data for the construction of metro depots, field measurements of vibration and noise on the ground and inside a nearby 3-story building subjected to moving subway trains were conducted in a metro depot at Guangzhou, China. The amplitudes and frequency contents of velocity levels were quantified and compared. The composite A-weighted equivalent sound levels and maximum sound levels were captured. The predicted models for vibration and noise of metro depot were proposed based on existing models and verified. It was found that the vertical vibrations were significantly greater than the horizontal vibrations on the ground and inside the building near the testing line. While at the throat area, the horizontal vibrations near the curved track were remarkably greater than the vertical vibrations. The attenuation of the vibrations with frequencies above 50 Hz was larger than the ones below 50 Hz, and the frequencies of vibration transmitting to adjacent buildings were mainly within 10-50 Hz. The largest equivalent sound level generated in the throat area was smaller than the testing line one, but the instantaneous maximum sound level induced by wheels squeal, contact between wheels and rail joints as well as turnout was close to or even greater than the testing line one. The predicted models gave a first estimation for design and assessment of newly built metro depots. Copyright © 2015 Elsevier B.V. All rights reserved.

Noise levels, noise annoyance, and hearing-related problems in a dental college.

PubMed

Ahmed, Hafiz Omer; Ali, Wesal Jasim

2017-05-04

Through a cross-sectional survey and integrated sound level meter, this research examined noise exposure and auditory- and nonauditory-related problems experienced by students of a dentistry college located in the United Arab Emirates (UAE). A structured interview questionnaire was used to examine hearing-related problems, noise annoyance, and awareness of 114 students toward noise. The results showed that maximum noise levels were between 65 and 79 dB(A) with peak levels (high and low frequencies) ranging between 89 and 93 dB(A). Around 80% of the students experienced a certain degree of noise annoyance; 54% reported one of the hearing-related problems; and about 10% claimed to have hearing loss to a certain extent. It is recommended that sound-absorbent materials be used during the construction of dental clinics and laboratories to reduce the noise levels.

Assessing underwater noise levels during pile-driving at an offshore windfarm and its potential effects on marine mammals.

PubMed

Bailey, Helen; Senior, Bridget; Simmons, Dave; Rusin, Jan; Picken, Gordon; Thompson, Paul M

2010-06-01

Marine renewable developments have raised concerns over impacts of underwater noise on marine species, particularly from pile-driving for wind turbines. Environmental assessments typically use generic sound propagation models, but empirical tests of these models are lacking. In 2006, two 5MW wind turbines were installed off NE Scotland. The turbines were in deep (>40m) water, 25km from the Moray Firth Special Area of Conservation (SAC), potentially affecting a protected population of bottlenose dolphins. We measured pile-driving noise at distances of 0.1 (maximum broadband peak to peak sound level 205dB re 1microPa) to 80km (no longer distinguishable above background noise). These sound levels were related to noise exposure criteria for marine mammals to assess possible effects. For bottlenose dolphins, auditory injury would only have occurred within 100m of the pile-driving and behavioural disturbance, defined as modifications in behaviour, could have occurred up to 50km away.

Spacecraft Internal Acoustic Environment Modeling

NASA Technical Reports Server (NTRS)

Chu, SShao-sheng R.; Allen, Christopher S.

2009-01-01

Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data. In FY09, the physical mockup developed in FY08, with interior geometric shape similar to Orion CM (Crew Module) IML (Interior Mode Line), was used to validate SEA (Statistical Energy Analysis) acoustic model development with realistic ventilation fan sources. The sound power levels of these sources were unknown a priori, as opposed to previous studies that RSS (Reference Sound Source) with known sound power level was used. The modeling results were evaluated based on comparisons to measurements of sound pressure levels over a wide frequency range, including the frequency range where SEA gives good results. Sound intensity measurement was performed over a rectangular-shaped grid system enclosing the ventilation fan source. Sound intensities were measured at the top, front, back, right, and left surfaces of the and system. Sound intensity at the bottom surface was not measured, but sound blocking material was placed tinder the bottom surface to reflect most of the incident sound energy back to the remaining measured surfaces. Integrating measured sound intensities over measured surfaces renders estimated sound power of the source. The reverberation time T6o of the mockup interior had been modified to match reverberation levels of ISS US Lab interior for speech frequency bands, i.e., 0.5k, 1k, 2k, 4 kHz, by attaching appropriately sized Thinsulate sound absorption material to the interior wall of the mockup. Sound absorption of Thinsulate was modeled in three methods: Sabine equation with measured mockup interior reverberation time T60, layup model based on past impedance tube testing, and layup model plus air absorption correction. The evaluation/validation was carried out by acquiring octave band microphone data simultaneously at ten fixed locations throughout the mockup. SPLs (Sound Pressure Levels) predicted by our SEA model match well with measurements for our CM mockup, with a more complicated shape. Additionally in FY09, background NC noise (Noise Criterion) simulation and MRT (Modified Rhyme Test) were developed and performed in the mockup to determine the maximum noise level in CM habitable volume for fair crew voice communications. Numerous demonstrations of simulated noise environment in the mockup and associated SIL (Speech Interference Level) via MRT were performed for various communities, including members from NASA and Orion prime-/sub-contractors. Also, a new HSIR (Human-Systems Integration Requirement) for limiting pre- and post-landing SIL was proposed.

The shouted voice: A pilot study of laryngeal physiology under extreme aerodynamic pressure.

PubMed

Lagier, Aude; Legou, Thierry; Galant, Camille; Amy de La Bretèque, Benoit; Meynadier, Yohann; Giovanni, Antoine

2017-12-01

The objective was to study the behavior of the larynx during shouted voice production, when the larynx is exposed to extremely high subglottic pressure. The study involved electroglottographic, acoustic, and aerodynamic analyses of shouts produced at maximum effort by three male participants. Under a normal speaking voice, the voice sound pressure level (SPL) is proportional to the subglottic pressure. However, when the subglottic pressure reached high levels, the voice SPL reached a maximum value and then decreased as subglottic pressure increased further. Furthermore, the electroglottographic signal sometimes lost its periodicity during the shout, suggesting irregular vocal fold vibration.

Observations of shallow water marine ambient sound: the low frequency underwater soundscape of the central Oregon coast.

PubMed

Haxel, Joseph H; Dziak, Robert P; Matsumoto, Haru

2013-05-01

A year-long experiment (March 2010 to April 2011) measuring ambient sound at a shallow water site (50 m) on the central OR coast near the Port of Newport provides important baseline information for comparisons with future measurements associated with resource development along the inner continental shelf of the Pacific Northwest. Ambient levels in frequencies affected by surf-generated noise (f < 100 Hz) characterize the site as a high-energy end member within the spectrum of shallow water coastal areas influenced by breaking waves. Dominant sound sources include locally generated ship noise (66% of total hours contain local ship noise), breaking surf, wind induced wave breaking and baleen whale vocalizations. Additionally, an increase in spectral levels for frequencies ranging from 35 to 100 Hz is attributed to noise radiated from distant commercial ship commerce. One-second root mean square (rms) sound pressure level (SPLrms) estimates calculated across the 10-840 Hz frequency band for the entire year long deployment show minimum, mean, and maximum values of 84 dB, 101 dB, and 152 dB re 1 μPa.

Spatial traffic noise pollution assessment - A case study.

PubMed

Monazzam, Mohammad Reza; Karimi, Elham; Abbaspour, Majid; Nassiri, Parvin; Taghavi, Lobat

2015-01-01

Spatial assessment of traffic noise pollution intensity will provide urban planners with approximate estimation of citizens exposure to impermissible sound levels. They could identify critical noise pollution areas wherein noise barriers should be embedded. The present study aims at using the Geographic Information System (GIS) to assess spatial changes in traffic noise pollution in Tehran, the capital of Iran, and the largest city in the Middle East. For this purpose, while measuring equivalent sound levels at different time periods of a day and different days of a week in District 14 of Tehran, wherein there are highways and busy streets, the geographic coordination of the measurement points was recorded at the stations. The obtained results indicated that the equivalent sound level did not show a statistically significant difference between weekdays, and morning, afternoon and evening hours as well as time intervals of 10 min, 15 min and 30 min. Then, 91 stations were selected in the target area and equivalent sound level was measured for each station on 3 occasions of the morning (7:00-9:00 a.m.), afternoon (12.00-3:00 p.m.) and evening (5:00-8:00 p.m.) on Saturdays to Wednesdays. As the results suggest, the maximum equivalent sound level (Leq) was reported from Basij Highway, which is a very important connecting thoroughfare in the district, and was equal to 84.2 dB(A), while the minimum equivalent sound level (Leq), measured in the Fajr Hospital, was equal to 59.9 dB(A). The average equivalent sound level was higher than the national standard limit at all stations. The use of sound walls in Highways Basij and Mahallati as well as widening the Streets 17th Shahrivar, Pirouzi and Khavaran, benchmarked on a map, were recommended as the most effective mitigation measures. Additionally, the research findings confirm the outstanding applicability of the Geographic Information System in handling noise pollution data towards depicting noise pollution intensity caused by traffic. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

24 CFR 51.106 - Implementation.

Code of Federal Regulations, 2011 CFR

2011-04-01

... data. HUD field staff shall make maximum use of noise data prepared by others when such data are... day-night average sound level data are not available may be evaluated from NEF or CNEL analyses using... LCdn. (4) Use of areawide acoustical data. HUD encourages the preparation and use of areawide...

[Assessment of acoustic environment and its effect on hearing in jet engine technical personnel].

PubMed

Konopka, Wiesław; Pawlaczyk-Luszczyńska, Małgorzata; Straszyński, Piotr; Sliwińska-Kowalska, Mariola

2004-01-01

Noise produced by jet engines may be harmful to aircraft servicing personnel because of high levels of acoustic pressure. The aim of the study was to assess the acoustic environment of persons exposed to jet engine noise and its effect on hearing. Noise measurements were performed on three jet engines. During the target practice, the following parameters were measured: equivalent noise, pressure level A, maximum sound pressure level A, and peak sound pressure level C. The spectro-analysis covering the range from 0.1 to 20 kHz was conducted. Hearing was assessed in 50 noise-exposed men, aged 24-51 years (mean age, 35.5 years), using PTA, tympanometry and DPOAE. The control group consisted of 40 non-exposed persons with good hearing condition. Maximum levels of acoustic pressure exceeded Polish standards. Comparison between two groups showed that PTA was higher in the exposed persons by 6.3-6.8 dB on average and DPOAE was reduced in the group exposed to jet engine noise more than it could have been expected. Even during a single test, aircraft technical personnel was exposed to (audible) noise that significantly exceeded admissible values. The reduction in DPOAE values in persons exposed to noise of jet engines was incommensurably higher than changes in PTA.

Narrow sound pressure level tuning in the auditory cortex of the bats Molossus molossus and Macrotus waterhousii.

PubMed

Macías, Silvio; Hechavarría, Julio C; Cobo, Ariadna; Mora, Emanuel C

2014-03-01

In the auditory system, tuning to sound level appears in the form of non-monotonic response-level functions that depict the response of a neuron to changing sound levels. Neurons with non-monotonic response-level functions respond best to a particular sound pressure level (defined as "best level" or level evoking the maximum response). We performed a comparative study on the location and basic functional organization of the auditory cortex in the gleaning bat, Macrotus waterhousii, and the aerial-hawking bat, Molossus molossus. Here, we describe the response-level function of cortical units in these two species. In the auditory cortices of M. waterhousii and M. molossus, the characteristic frequency of the units increased from caudal to rostral. In M. waterhousii, there was an even distribution of characteristic frequencies while in M. molossus there was an overrepresentation of frequencies present within echolocation pulses. In both species, most of the units showed best levels in a narrow range, without an evident topography in the amplitopic organization, as described in other species. During flight, bats decrease the intensity of their emitted pulses when they approach a prey item or an obstacle resulting in maintenance of perceived echo intensity. Narrow level tuning likely contributes to the extraction of echo amplitudes facilitating echo-intensity compensation. For aerial-hawking bats, like M. molossus, receiving echoes within the optimal sensitivity range can help the bats to sustain consistent analysis of successive echoes without distortions of perception caused by changes in amplitude. Copyright © 2013 Elsevier B.V. All rights reserved.

Sources and levels of ambient ocean sound near the antarctic peninsula

DOE PAGES

Dziak, Robert P.; Bohnenstiehl, DelWayne R.; Stafford, Kathleen M.; ...

2015-04-14

Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (Antarctic Peninsula region) from 2005 to 2009 to record ambient ocean sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the ocean soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapid disintegration also releases significant acoustic energy, equivalent to large-scale geophysical events. Overall ambient sound levels can be as much as ~10–20 dB higher in the open,more » deep ocean of the Scotia Sea compared to the relatively shallow Bransfield Strait. Noise levels become lowest during the austral winter, as sea-ice cover suppresses wind and wave noise. Ambient noise levels are highest during austral spring and summer, as surface noise, ice cracking and biological activity intensifies. Vocalizations of blue ( Balaenoptera musculus) and fin ( B. physalus) whales also dominate the long-term spectra records in the 15–28 and 89 Hz bands. Blue whale call energy is a maximum during austral summer-fall in the Drake Passage and Bransfield Strait when ambient noise levels are a maximum and sea-ice cover is a minimum. Fin whale vocalizations were also most common during austral summer-early fall months in both the Bransfield Strait and Scotia Sea. The hydrophone data overall do not show sustained anthropogenic sources (ships and airguns), likely due to low coastal traffic and the typically rough weather and sea conditions of the Southern Ocean.« less

A three-dimensional integrated nanogenerator for effectively harvesting sound energy from the environment.

PubMed

Liu, Jinmei; Cui, Nuanyang; Gu, Long; Chen, Xiaobo; Bai, Suo; Zheng, Youbin; Hu, Caixia; Qin, Yong

2016-03-07

An integrated triboelectric nanogenerator (ITNG) with a three-dimensional structure benefiting sound propagation and adsorption is demonstrated to more effectively harvest sound energy with improved output performance. With different multifunctional integrated layers working harmonically, it could generate a short-circuit current up to 2.1 mA, an open-circuit voltage up to 232 V and the maximum charging rate can reach 453 μC s(-1) for a 1 mF capacitor, which are 4.6 times, 2.6 times and 7.4 times the highest reported values, respectively. Further study shows that the ITNG works well under sound in a wide range of sound intensity levels (SILs) and frequencies, and its output is sensitive to the SIL and frequency of the sound, which reveals that the ITNG can act as a self-powered active sensor for real-time noise surveillance and health care. Moreover, this generator can be used to directly power the Fe(OH)3 sol electrophoresis and shows great potential as a wireless power supply in the electrochemical industry.

40 CFR 205.174 - Remedial orders.

Code of Federal Regulations, 2010 CFR

2010-07-01

... power (maximum rated RPM) is developed; and (B) Response characteristics such that, when closing RPM is...-state accuracy of within ±10% at 20 km/h (12.4 mph). (5) A microphone wind screen which does not affect... microphone wind screen must be used. The sound level meter must be calibrated with the acoustic calibrator as...

Sound levels, hearing habits and hazards of using portable cassete players

NASA Astrophysics Data System (ADS)

Hellström, P.-A.; Axelsson, A.

1988-12-01

The maximum output sound pressure level ( SPL) from different types of portable cassette players (PCP's) and different headphones was analyzed by using KEMAR in one-third octave bands. The equivalent free-field dB(A) level (EqA-FFSL) was computed from the one-third octave bands corrected by the free-field to the eardrum transfer function. The dB(A) level varied between 104 dB from a low-cost PCP with supra-aural headphones (earphones with headbands and foam pads fitting against the pinna) to 126 dB from a high quality PCP with semi-aural headphones (small earphones without headbands to be used in the concha of the external ear). The cassette tapes used in this study were recorded with music, white noise, narrowband noise and pure tones. The equivalent and maximum SPL was measured in the ear canal (1 mm from eardrum) with the use of mini-microphones in 15 young subjects listening to pop music from PCP's at the highest level they considered comfortable. These SPL measurements corresponded to 112 dB(A) in free field. In a temporary threshold shift ( TTS) study, ten teenagers—four girls and six boys—listened to pop music for 1 h with PCP's at a level they enjoyed. The mean TTS value was 5-10 dB for frequencies between 1 and 8 kHz. In one subject the maximum TTS was 35 dB at 5-6 dB kHz. In order to acquire information about listening habits among youngsters using PCP's, 154 seventh and eighth graders (age 14-15) were interviewed. They used PCP's much less than expected during most of the year, but an increase was reported during the summer holidays.

Aeroacoustic model of a modulation fan with pitching blades as a sound generator.

PubMed

Du, Lin; Jing, Xiaodong; Sun, Xiaofeng; Song, Weihua

2014-10-01

This paper is to develop an aeroacoustic model for a type of modulation fan termed as rotary subwoofer that is capable of radiating low-frequency sound at high sound pressure levels. The rotary subwoofer is modeled as a baffled monopole whose source strength is specified by the fluctuating mass flow rate produced by the pitching blades that rotate at constant speed. An immersed boundary method is established to simulate the detailed unsteady flow around the blades and also to estimate the source strength for the prediction of the far-field sound pressure level (SPL). The numerical simulation shows that the rotary subwoofer can output oscillating air flow that is in phase with the pitching motion of the blades. It is found that flow separation is more likely to occur on the pitching blades at higher modulation frequency, resulting in the reduction of the radiated SPL. Increasing the maximum blade excursion is one of the most effective means to enhance the sound radiation, but this effect can also be compromised by the flow separation. As the modulation frequency increases, correspondingly increasing the rotational speed or using larger blade solidity is beneficial to suppressing the flow separation and thus improving the acoustic performance of the rotary subwoofer.

Pilot survey of subway and bus stop noise levels.

PubMed

Gershon, Robyn R M; Neitzel, Richard; Barrera, Marissa A; Akram, Muhammad

2006-09-01

Excessive noise exposure is a serious global urban health problem, adversely affecting millions of people. One often cited source of urban noise is mass transit, particularly subway systems. As a first step in determining risk within this context, we recently conducted an environmental survey of noise levels of the New York City transit system. Over 90 noise measurements were made using a sound level meter. Average and maximum noise levels were measured on subway platforms, and maximum levels were measured inside subway cars and at several bus stops for comparison purposes. The average noise level measured on the subway platforms was 86 +/- 4 dBA (decibel-A weighting). Maximum levels of 106, 112, and 89 dBA were measured on subway platforms, inside subway cars, and at bus stops, respectively. These results indicate that noise levels in subway and bus stop environments have the potential to exceed recommended exposure guidelines from the World Health Organization (WHO) and U.S. Environmental Protection Agency (EPA), given sufficient exposure duration. Risk reduction strategies following the standard hierarchy of control measures should be applied, where feasible, to reduce subway noise exposure.

Masking release by combined spatial and masker-fluctuation effects in the open sound field.

PubMed

Middlebrooks, John C

2017-12-01

In a complex auditory scene, signals of interest can be distinguished from masking sounds by differences in source location [spatial release from masking (SRM)] and by differences between masker-alone and masker-plus-signal envelopes. This study investigated interactions between those factors in release of masking of 700-Hz tones in an open sound field. Signal and masker sources were colocated in front of the listener, or the signal source was shifted 90° to the side. In Experiment 1, the masker contained a 25-Hz-wide on-signal band plus flanking bands having envelopes that were either mutually uncorrelated or were comodulated. Comodulation masking release (CMR) was largely independent of signal location at a higher masker sound level, but at a lower level CMR was reduced for the lateral signal location. In Experiment 2, a brief signal was positioned at the envelope maximum (peak) or minimum (dip) of a 50-Hz-wide on-signal masker. Masking was released in dip more than in peak conditions only for the 90° signal. Overall, open-field SRM was greater in magnitude than binaural masking release reported in comparable closed-field studies, and envelope-related release was somewhat weaker. Mutual enhancement of masking release by spatial and envelope-related effects tended to increase with increasing masker level.

Design and development of multipurpose Kundt’s tube as physics learning media

NASA Astrophysics Data System (ADS)

Nursulistiyo, E.

2018-03-01

Research had been conducted to develop Multipurpose Kundt's tube as a physics learning media. Research background was the absence of sound waves visualization to improve the understanding of learners. The purposes of this research were to develop Multipurpose Kundt’s tube as physics learning media and to test its feasibility. The developed tool was tested to find the speed of sound in the air, showing the double slit interference phenomenon of the sound, and show the temperature changes in the cold and heat reservoirs in the thermoacoustic process. The development step that had been used was Preliminary Study, Development, Field Test, and Dissemination or known as PDFD Model. On the implementation, the dissemination process was not done. The test was done by the experts, peers, and college students to find out the media feasibility level. The speed of sound in the air which was measured using Multipurpose Kundt’s tube obtained v ± Δv = 263 ± 24 m/s with the closeness value of 76.63% closer to the theoretical value. Also, it was founded a calibration factor of 1.32. The tool was able to show sound waves on the open-end tube. The value of the distance between minimum and maximum interferences between the experimental results compared to theory was almost the same, so it was concluded that the phenomenon of double-slit interference of the sound could be shown by the tool. The thermoacoustic phenomenon could be observed and gave maximum temperature 31.4°C in the hot reservoir, and minimum temperature 24°C in the cold reservoir at the frequency of 119 Hz. Temperature differences obtained 7.4°C. The result of the feasibility test obtained the average result of 88.23 in a “Very Good” category.

Effects of acupuncture on the heart rate variability, cortisol levels and behavioural response induced by thunder sound in beagles.

PubMed

Maccariello, Carolina Elisabetta Martins; Franzini de Souza, Carla Caroline; Morena, Laura; Dias, Daniel Penteado Martins; Medeiros, Magda Alves de

2018-03-15

Sound stimuli such as fireworks, firearms, and claps of thunder have been used as a stress reactivity model for dogs. Acupuncture has been widely used to treat and prevent physiological and behavioural disorders induced by stress. Our study aims to evaluate the effects of acupuncture on cardiac autonomic modulation (heart rate variability - HRV), behavioural (reactivity) and endocrine (cortisol levels) responses in dogs exposed to sounds of thunder. Twenty-four laboratory beagles (12 males and 12 females, 1-6years old) with no history of phobia to thunder were subjected to a sound stimulus that consisted of a standardized recording of thunder over a 150s period with a maximum intensity of 103-104dB. Before the sound, the dogs underwent a 20-minute session of needle insertion at acupuncture points Yintang, GV20, HT7, PC6 and ST36 (ACUP), in non-points (NP) or left undisturbed (CTL). Cardiac intervals were recorded using a frequency meter (RS 800cx, Polar, Kempele, Finland) to evaluate the HRV, and the data were later analysed using CardioSeries v2.4.1 software. Acupuncture (ACUP) changed the sympathovagal balance with a shift towards parasympathetic modulation, reducing the prompt sound-induced increase in LF/HF (low frequency/high frequency) ratio and in the power of the LF band of the cardiac interval spectrum, and decreased the power of the HF band of the cardiac interval spectrum (p<0.05); however there was no change in the heart rate. Acupuncture reduced the behavioural response induced by sounds of thunder (when all behavioural parameters were considered together) and the behaviours hiding, restlessness, bolting and running around (when the parameters were analysed separately (p<0.05). There were no changes in cortisol levels due to the sound stimulus or acupuncture. Our results demonstrate that a session of acupuncture prior to sound stimulus can reduce cardiac autonomic and behavioural responses, without changing cortisol levels in beagles. Copyright © 2018 Elsevier Inc. All rights reserved.

Impacts of historic morphology and sea level rise on tidal hydrodynamics in a microtidal estuary (Grand Bay, Mississippi)

NASA Astrophysics Data System (ADS)

Passeri, Davina L.; Hagen, Scott C.; Medeiros, Stephen C.; Bilskie, Matthew V.

2015-12-01

This study evaluates the geophysical influence of the combined effects of historic sea level rise (SLR) and morphology on tidal hydrodynamics in the Grand Bay estuary, located in the Mississippi Sound. Since 1848, the landscape of the Mississippi Sound has been significantly altered as a result of natural and anthropogenic factors including the migration of the offshore Mississippi-Alabama (MSAL) barrier islands and the construction of navigational channels. As a result, the Grand Bay estuary has undergone extensive erosion resulting in the submergence of its protective barrier island, Grand Batture. A large-domain hydrodynamic model was used to simulate present (circa 2005) and past conditions (circa 1848, 1917, and 1960) with unique sea levels, bathymetry, topography and shorelines representative of each time period. Additionally, a hypothetical scenario was performed in which Grand Batture Island exists under 2005 conditions in order to observe the influence of the island on tidal hydrodynamics within the Grand Bay estuary. Changes in tidal amplitudes from the historic conditions varied. Within the Sound, tidal amplitudes were unaltered due to the open exposed shoreline; however, in semi-enclosed embayments outside of the Sound, tidal amplitudes increased. In addition, harmonic constituent phases were slower historically. The position of the MSAL barrier island inlets influenced tidal currents within the Sound; the westward migration of Petit Bois Island allowed stronger tidal velocities to be centered on the Grand Batture Island. Maximum tidal velocities within the Grand Bay estuary were 5 cm/s faster historically, and reversed from being flood dominant in 1848 to ebb dominant in 2005. If the Grand Batture Island was reconstructed under 2005 conditions, tidal amplitudes and phases would not be altered, indicating that the offshore MSAL barrier islands and SLR have a greater influence on these tidal parameters within the estuary. However, maximum tidal velocities would increase by as much as 5 cm/s (63%) and currents would become more ebb dominant. Results of this study illustrate the hydrodynamic response of the system to SLR and the changing landscape, and provide insight into potential future changes under SLR and barrier island evolution.

Comparison between uroflowmetry and sonouroflowmetry in recording of urinary flow in healthy men.

PubMed

Krhut, Jan; Gärtner, Marcel; Sýkora, Radek; Hurtík, Petr; Burda, Michal; Luňáček, Libor; Zvarová, Katarína; Zvara, Peter

2015-08-01

To evaluate the accuracy of sonouroflowmetry in recording urinary flow parameters and voided volume. A total of 25 healthy male volunteers (age 18-63 years) were included in the study. All participants were asked to carry out uroflowmetry synchronous with recording of the sound generated by the urine stream hitting the water level in the urine collection receptacle, using a dedicated cell phone. From 188 recordings, 34 were excluded, because of voided volume <150 mL or technical problems during recording. Sonouroflowmetry recording was visualized in a form of a trace, representing sound intensity over time. Subsequently, the matching datasets of uroflowmetry and sonouroflowmetry were compared with respect to flow time, voided volume, maximum flow rate and average flow rate. Pearson's correlation coefficient was used to compare parameters recorded by uroflowmetry with those calculated based on sonouroflowmetry recordings. The flow pattern recorded by sonouroflowmetry showed a good correlation with the uroflowmetry trace. A strong correlation (Pearson's correlation coefficient 0.87) was documented between uroflowmetry-recorded flow time and duration of the sound signal recorded with sonouroflowmetry. A moderate correlation was observed in voided volume (Pearson's correlation coefficient 0.68) and average flow rate (Pearson's correlation coefficient 0.57). A weak correlation (Pearson's correlation coefficient 0.38) between maximum flow rate recorded using uroflowmetry and sonouroflowmetry-recorded peak sound intensity was documented. The present study shows that the basic concept utilizing sound analysis for estimation of urinary flow parameters and voided volume is valid. However, further development of this technology and standardization of recording algorithm are required. © 2015 The Japanese Urological Association.

ARSENIC IN DRINKING WATER: USING SOUND SCIENCE FOR RISK MANAGEMENT AND ASSISTING COMMUNITY DECISION-MAKERS - A MULTI-AGENCY, COMMUNITY-BASED RESEARCH PROJECT

EPA Science Inventory

Studies have indicated that arsenic concentrations greater than the new U.S. Environmental Protection Agency (U.S. EPA) maximum contaminant level (MCL) concentration of 10 micrograms per liter (ug/L) occur in numerous aquifers around the United States. One such aquifer is the Cen...

Sound field inside acoustically levitated spherical drop

NASA Astrophysics Data System (ADS)

Xie, W. J.; Wei, B.

2007-05-01

The sound field inside an acoustically levitated small spherical water drop (radius of 1mm) is studied under different incident sound pressures (amplitude p0=2735-5643Pa). The transmitted pressure ptr in the drop shows a plane standing wave, which varies mainly in the vertical direction, and distributes almost uniformly in the horizontal direction. The maximum of ptr is always located at the lowermost point of the levitated drop. Whereas the secondary maximum appears at the uppermost point if the incident pressure amplitude p0 is higher than an intermediate value (3044Pa), in which there exists a pressure nodal surface in the drop interior. The value of the maximum ptr lies in a narrow range of 2489-3173Pa, which has a lower limit of 2489Pa when p0=3044Pa. The secondary maximum of ptr is rather small and only remarkable at high incident pressures.

The role of soundscape in children's learning

NASA Astrophysics Data System (ADS)

Lubman, David; Sutherland, Louis C.

2002-11-01

The soundscapes of classroom and play areas influence children's behavior and learning. For example, the sustained high noise levels of shouting children frequently reported in day care centers are averse to behavior, learning, and teaching. To some extent this Lombard effect, or reflex to the reverberant buildup of room noise, can be tamed by generous application of sound absorption treatment to room surfaces. Low ambient noise allows children to perceive and enjoy quiet sounds, such as the subtle sounds of pets housed in classrooms. The benefits of improved interior soundscape may justify reducing reverberation time below the maximum value of 0.6 s permitted in the new classroom acoustics standard ANSI S12.60-2002. Exterior play areas are also vital to children's socialization, informal learning, and environmental awareness. Reducing noise in outdoor play areas will promote the development of soundscapes favorable to learning. This paper suggests uses of natural outdoor soundscapes to promote learning. Also shown are uses of acoustical technology for sound playgrounds, such as those pioneered by Bill and Mary Bucken. Using such devices as sound focusing structures and sound transission channels built into playground equipment, sonic playgrounds stimulate learning, increase sonic awareness, and provide experiential enjoyment of the soundscape.

A Methodology to Objectively Assess the Performance of Sound Field Amplification Systems Demonstrated Using 50 Physical Simulations of Classroom Conditions

PubMed Central

Dance, Stephen; Backus, Bradford; Morales, Lorenzo

2018-01-01

Introduction: The effect of a sound reinforcement system, in terms of speech intelligibility, has been systematically determined under realistic conditions. Different combinations of ambient and reverberant conditions representative of a classroom environment have been investigated. Materials and Methods: By comparing the measured speech transmission index metric with and without the system in the same space under different room acoustics conditions, it was possible to determine when the system was most effective. A new simple criterion, equivalent noise reduction (ENR), was introduced to determine the effectiveness of the sound reinforcement system which can be used to predict the speech transmission index based on the ambient sound pressure and reverberation time with and without amplification. Results: This criterion had a correlation, R2 > 0.97. It was found that sound reinforcement provided no benefit if the competing noise level was less than 40 dBA. However, the maximum benefit of such a system was equivalent to a 7.7 dBA noise reduction. Conclusion: Using the ENR model, it would be possible to determine the suitability of implementing sound reinforcement systems in any room, thus providing a tool to determine if natural acoustic treatment or sound field amplification would be of most benefit to the occupants of any particular room. PMID:29785972

A methodology to objectively assess the performance of sound field amplification systems demonstrated using 50 physical simulations of classroom conditions.

PubMed

Dance, Stephen; Backus, Bradford; Morales, Lorenzo

2018-01-01

The effect of a sound reinforcement system, in terms of speech intelligibility, has been systematically determined under realistic conditions. Different combinations of ambient and reverberant conditions representative of a classroom environment have been investigated. By comparing the measured speech transmission index metric with and without the system in the same space under different room acoustics conditions, it was possible to determine when the system was most effective. A new simple criterion, equivalent noise reduction (ENR), was introduced to determine the effectiveness of the sound reinforcement system which can be used to predict the speech transmission index based on the ambient sound pressure and reverberation time with and without amplification. This criterion had a correlation, R 2 > 0.97. It was found that sound reinforcement provided no benefit if the competing noise level was less than 40 dBA. However, the maximum benefit of such a system was equivalent to a 7.7 dBA noise reduction. Using the ENR model, it would be possible to determine the suitability of implementing sound reinforcement systems in any room, thus providing a tool to determine if natural acoustic treatment or sound field amplification would be of most benefit to the occupants of any particular room.

Development of a Korotkov sound processor for automatic identification of auscultatory events. I - Specification of preprocessing bandpass filters

NASA Technical Reports Server (NTRS)

Golden, D. P., Jr.; Wolthuis, R. A.; Hoffler, G. W.; Gowen, R. J.

1974-01-01

Frequency bands that best discriminate the Korotkov sounds at systole and at diastole from the sounds immediately preceding these events are defined. Korotkov sound data were recorded from five normotensive subjects during orthostatic stress (lower body negative pressure) and bicycle ergometry. A spectral analysis of the seven Korotkov sounds centered about the systolic and diastolic auscultatory events revealed that a maximum increase in amplitude at the systolic transition occurred in the 18-26-Hz band, while a maximum decrease in amplitude at the diastolic transition occurred in the 40-60-Hz band. These findings were remarkably consistent across subjects and test conditions. These passbands are included in the design specifications for an automatic blood pressure measuring system used in conjuction with medical experiments during NASA's Skylab program.

Aerodynamic sound generation of flapping wing.

PubMed

Bae, Youngmin; Moon, Young J

2008-07-01

The unsteady flow and acoustic characteristics of the flapping wing are numerically investigated for a two-dimensional model of Bombus terrestris bumblebee at hovering and forward flight conditions. The Reynolds number Re, based on the maximum translational velocity of the wing and the chord length, is 8800 and the Mach number M is 0.0485. The computational results show that the flapping wing sound is generated by two different sound generation mechanisms. A primary dipole tone is generated at wing beat frequency by the transverse motion of the wing, while other higher frequency dipole tones are produced via vortex edge scattering during a tangential motion. It is also found that the primary tone is directional because of the torsional angle in wing motion. These features are only distinct for hovering, while in forward flight condition, the wing-vortex interaction becomes more prominent due to the free stream effect. Thereby, the sound pressure level spectrum is more broadband at higher frequencies and the frequency compositions become similar in all directions.

The nocturnal acoustical intensity of the intensive care environment: an observational study.

PubMed

Delaney, Lori J; Currie, Marian J; Huang, Hsin-Chia Carol; Lopez, Violeta; Litton, Edward; Van Haren, Frank

2017-01-01

The intensive care unit (ICU) environment exposes patients to noise levels that may result in substantial sleep disruption. There is a need to accurately describe the intensity pattern and source of noise in the ICU in order to develop effective sound abatement strategies. The objectives of this study were to determine nocturnal noise levels and their variability and the related sources of noise within an Australian tertiary ICU. An observational cross-sectional study was conducted in a 24-bed open-plan ICU. Sound levels were recorded overnight during three nights at 5-s epochs using Extech (SDL 600) sound monitors. Noise sources were concurrently logged by two research assistants. The mean recorded ambient noise level in the ICU was 52.85 decibels (dB) (standard deviation (SD) 5.89), with a maximum noise recording at 98.3 dB (A). All recorded measurements exceeded the WHO recommendations. Noise variability per minute ranged from 9.9 to 44 dB (A), with peak noise levels >70 dB (A) occurring 10 times/hour (SD 11.4). Staff were identified as the most common source accounting for 35% of all noise. Mean noise levels in single-patient rooms compared with open-bed areas were 53.5 vs 53 dB ( p  = 0.37), respectively. Mean noise levels exceeded those recommended by the WHO resulting in an acoustical intensity of 193 times greater than the recommended and demonstrated a high degree of unpredictable variability, with the primary noise sources coming from staff conversations. The lack of protective effects of single rooms and the contributing effects that staffs have on noise levels are important factors when considering sound abatement strategies.

Determining the Probability of Violating Upper-Level Wind Constraints for the Launch of Minuteman III Ballistic Missiles at Vandenberg Air Force Base

NASA Technical Reports Server (NTRS)

Shafer, Jaclyn A.; Brock, Tyler M.

2012-01-01

The 30th Operational Support Squadron Weather Flight (30 OSSWF) provides comprehensive weather services to the space program at Vandenberg Air Force Base (VAFB) in California. One of their responsibilities is to monitor upper-level winds to ensure safe launch operations of the Minuteman Ill ballistic missile. The 30 OSSWF tasked the Applied Meteorology Unit (AMU) to analyze VAFB sounding data with the goal of determining the probability of violating (PoV) their upper-level thresholds for wind speed and shear constraints specific to this launch vehicle, and to develop a tool that will calculate the PoV of each constraint on the day of launch. In order to calculate the probability of exceeding each constraint, the AMU collected and analyzed historical data from VAFB. The historical sounding data were retrieved from the National Oceanic and Atmospheric Administration Earth System Research Laboratory archive for the years 1994-2011 and then stratified into four sub-seasons: January-March, April-June, July-September, and October-December. The AMU determined the theoretical distributions that best fit the maximum wind speed and maximum wind shear datasets and applied this information when calculating the averages and standard deviations needed for the historical and real-time PoV calculations. In addition, the AMU included forecast sounding data from the Rapid Refresh model. This information provides further insight for the launch weather officers (LWOs) when determining if a wind constraint violation will occur over the next few hours on the day of launch. The AMU developed an interactive graphical user interface (GUI) in Microsoft Excel using Visual Basic for Applications. The GUI displays the critical sounding data easily and quickly for LWOs on day of launch. This tool will replace the existing one used by the 30 OSSWF, assist the LWOs in determining the probability of exceeding specific wind threshold values, and help to improve the overall upper winds forecast for the launch customer. This presentation will describe how the AMU calculated the historical and real-time PoV values for the specific upper-level wind launch constraints and outline the development of the interactive GUI display.

16 CFR 1500.47 - Method for determining the sound pressure level produced by toy caps.

Code of Federal Regulations, 2012 CFR

2012-01-01

...'s instructions. (2) The oscilloscope shall be the storage type or one equipped with a camera. It...) Fire 10 shots at each of the six orientations, obtaining readings on the oscilloscope of the maximum peak voltage for each shot. Average the results of the 10 firings for each of the six orientations. (4...

16 CFR 1500.47 - Method for determining the sound pressure level produced by toy caps.

Code of Federal Regulations, 2010 CFR

2010-01-01

...'s instructions. (2) The oscilloscope shall be the storage type or one equipped with a camera. It...) Fire 10 shots at each of the six orientations, obtaining readings on the oscilloscope of the maximum peak voltage for each shot. Average the results of the 10 firings for each of the six orientations. (4...

16 CFR § 1500.47 - Method for determining the sound pressure level produced by toy caps.

Code of Federal Regulations, 2013 CFR

2013-01-01

...'s instructions. (2) The oscilloscope shall be the storage type or one equipped with a camera. It...) Fire 10 shots at each of the six orientations, obtaining readings on the oscilloscope of the maximum peak voltage for each shot. Average the results of the 10 firings for each of the six orientations. (4...

16 CFR 1500.47 - Method for determining the sound pressure level produced by toy caps.

Code of Federal Regulations, 2011 CFR

2011-01-01

...'s instructions. (2) The oscilloscope shall be the storage type or one equipped with a camera. It...) Fire 10 shots at each of the six orientations, obtaining readings on the oscilloscope of the maximum peak voltage for each shot. Average the results of the 10 firings for each of the six orientations. (4...

Pilot Survey of Subway and Bus Stop Noise Levels

PubMed Central

Neitzel, Richard; Barrera, Marissa A.; Akram, Muhammad

2006-01-01

Excessive noise exposure is a serious global urban health problem, adversely affecting millions of people. One often cited source of urban noise is mass transit, particularly subway systems. As a first step in determining risk within this context, we recently conducted an environmental survey of noise levels of the New York City transit system. Over 90 noise measurements were made using a sound level meter. Average and maximum noise levels were measured on subway platforms, and maximum levels were measured inside subway cars and at several bus stops for comparison purposes. The average noise level measured on the subway platforms was 86 ± 4 dBA (decibel-A weighting). Maximum levels of 106, 112, and 89 dBA were measured on subway platforms, inside subway cars, and at bus stops, respectively. These results indicate that noise levels in subway and bus stop environments have the potential to exceed recommended exposure guidelines from the World Health Organization (WHO) and U.S. Environmental Protection Agency (EPA), given sufficient exposure duration. Risk reduction strategies following the standard hierarchy of control measures should be applied, where feasible, to reduce subway noise exposure. PMID:16802179

Experimental study of outdoor propagation of spherically speading periodic acoustic waves of finite amplitude

NASA Technical Reports Server (NTRS)

Theobald, M. A.

1977-01-01

The outdoor propagation of spherically spreading sound waves of finite amplitude was investigated. The main purpose of the experiments was to determine the extent to which the outdoor environment, mainly random inhomogeneity of the medium, affects finite amplitude propagation. Periodic sources with fundamental frequencies in the range 6 to 8 kHz and source levels SPLlm from 140 to 149 dB were used. The sources were an array of 7 to 10 horn drivers and a siren. The propagation path was vertical and parallel to an 85 m tower, whose elevator carried the traveling microphone. The general conclusions drawn from the experimental results were as follows. The inhomogeneities caused significant fluctuations in the instantaneous acoustic signal, but with sufficient time averaging of the measured harmonic levels, the results were comparable to results expected for propagation in a quiet medium. Propagation data for the fundamental of the siren approached within 1 dB of the weak shock saturation levels. Extra attenuation on the order of 8 dB was observed. The measurements generally confirmed the predictions of several theoretical models. The maximum propagation distance was 36 m. The narrowbeam arrays were much weaker sources. Nonlinear propagation distortion was produced, but the maximum value of extra attenuation measured was 1.5 dB. The maximum propagation distance was 76 m. The behavior of the asymetric waveforms received in one experiment qualitatively suggested that beam type diffraction effects were present. The role of diffraction of high intensity sound waves in radiation from a single horn was briefly investigated.

Trends and annual cycles in soundings of Arctic tropospheric ozone

NASA Astrophysics Data System (ADS)

Christiansen, Bo; Jepsen, Nis; Kivi, Rigel; Hansen, Georg; Larsen, Niels; Smith Korsholm, Ulrik

2017-08-01

Ozone soundings from nine Nordic stations have been homogenized and interpolated to standard pressure levels. The different stations have very different data coverage; the longest period with data is from the end of the 1980s to 2014. At each pressure level the homogenized ozone time series have been analysed with a model that includes both low-frequency variability in the form of a polynomial, an annual cycle with harmonics, the possibility for low-frequency variability in the annual amplitude and phasing, and either white noise or noise given by a first-order autoregressive process. The fitting of the parameters is performed with a Bayesian approach not only giving the mean values but also confidence intervals. The results show that all stations agree on a well-defined annual cycle in the free troposphere with a relatively confined maximum in the early summer. Regarding the low-frequency variability, it is found that Scoresbysund, Ny Ålesund, Sodankylä, Eureka, and Ørland show similar, significant signals with a maximum near 2005 followed by a decrease. This change is characteristic for all pressure levels in the free troposphere. A significant change in the annual cycle was found for Ny Ålesund, Scoresbysund, and Sodankylä. The changes at these stations are in agreement with the interpretation that the early summer maximum is appearing earlier in the year. The results are shown to be robust to the different settings of the model parameters such as the order of the polynomial, number of harmonics in the annual cycle, and the type of noise.

Second sound shock waves and critical velocities in liquid helium 2. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Turner, T. N.

1979-01-01

Large amplitude second-sound shock waves were generated and the experimental results compared to the theory of nonlinear second-sound. The structure and thickness of second-sound shock fronts are calculated and compared to experimental data. Theoretically it is shown that at T = 1.88 K, where the nonlinear wave steepening vanishes, the thickness of a very weak shock must diverge. In a region near this temperature, a finite-amplitude shock pulse evolves into an unusual double-shock configuration consisting of a front steepened, temperature raising shock followed by a temperature lowering shock. Double-shocks are experimentally verified. It is experimentally shown that very large second-sound shock waves initiate a breakdown in the superfluidity of helium 2, which is dramatically displayed as a limit to the maximum attainable shock strength. The value of the maximum shock-induced relative velocity represents a significant lower bound to the intrinsic critical velocity of helium 2.

A Description of Methodologies Used in Estimation of A-Weighted Sound Levels for FAA Advisory Circular AC-36-3B.

DTIC Science & Technology

1982-01-01

second) Dia propeller diameter (expressed in inches) T°F air temperature in degrees Farenheit T°C air temperature in degrees Celsius T:dBA total dBA...eMpiriC31 function to the absolute noise level ordinate. The term 240 log ( MH is the most sensitive and important part of the equation. The constant (240...standard day, zero wind, dry, zero gradient runway, at a sea level airport. 2. All aircraft operate at maximum takeoff gross weight. 3. All aircraft climb

The design and development of an automatic control system for the in-duct cancellation of spinning modes of sound. M.S. Thesis

NASA Technical Reports Server (NTRS)

Harrington, W. W.

1973-01-01

The reduction is discussed of the discrete tones generated by jet engines which is essential for jet aircraft to meet present and proposed noise standards. The discrete tones generated by the blades and vanes propagate in the inlet and exhaust duct in the form of spiraling acoustic waves, or spinning modes. The reduction of these spinning modes by the cancellation effect of the combination of two acoustic fields was investigated. The spinning mode synthesizer provided the means for effective study of this noise reduction scheme. Two sets of electrical-acoustical transducers located in an equally-spaced circular array simultaneously generate a specified spinning mode and the cancelling mode. Analysis of the wave equation for the synthesizer established the optimum cancelling array acoustic parameters for maximum sound pressure level reduction. The parameter dependence of the frequency ranges of propagation of single, specified circumferential modes generated by a single array, and of effective cancellation of the modes generated by two arrays, was determined. Substantial sound pressure level reduction was obtained for modes within these limits.

Velocity and bottom-stress measurements in the bottom boundary layer, outer Norton Sound, Alaska.

USGS Publications Warehouse

Cacchione, D.A.; Drake, D.E.; Wiberg, P.

1982-01-01

We have used long-term measurements of near-bottom velocities at four heights above the sea floor in Norton Sound, Alaska, to compute hourly values of shear velocity u., roughness and bottom-drag coefficient. Maximum sediment resuspension and transport, predicted for periods when the computed value of u. exceeds a critical level, occur during peak tidal currents associated with spring tides. The fortnightly variation in u. is correlated with a distinct nepheloid layer that intensifies and thickens during spring tides and diminishes and thins during neap tides. The passage of a storm near the end of the experiment caused significantly higher u. values than those found during fair weather.-from Authros

The maximum single dose of resistant maltodextrin that does not cause diarrhea in humans.

PubMed

Kishimoto, Yuka; Kanahori, Sumiko; Sakano, Katsuhisa; Ebihara, Shukuko

2013-01-01

The objective of the present study was to determine the maximum dose of resistant maltodextrin (Fibersol)-2, a non-viscous water-soluble dietary fiber), that does not induce transitory diarrhea. Ten healthy adult subjects (5 men and 5 women) ingested Fibersol-2 at increasing dose levels of 0.7, 0.8, 0.9, 1.0, and 1.1 g/kg body weight (bw). Each administration was separated from the previous dose by an interval of 1 wk. The highest dose level that did not cause diarrhea in any subject was regarded as the maximum non-effective level for a single dose. The results showed that no subject of either sex experienced diarrhea at dose levels of 0.7, 0.8, 0.9, or 1.0 g/kg bw. At the highest dose level of 1.1 g/kg bw, no female subject experienced diarrhea, whereas 1 male subject developed diarrhea with muddy stools 2 h after ingestion of the test substance. Consequently, the maximum non-effective level for a single dose of the resistant maltodextrin Fibersol-2 is 1.0 g/kg bw for men and >1.1 g/kg bw for women. Gastrointestinal symptoms were gurgling sounds in 4 subjects (7 events) and flatus in 5 subjects (9 events), although no association with dose level was observed. These symptoms were mild and transient and resolved without treatment.

[Equivalent continuous noise level in neonatal intensive care unit associated to burnout syndrome].

PubMed

Garrido Galindo, A P; Camargo Caicedo, Y; Vélez-Pereira, A M

2015-01-01

Noise levels in neonatal intensive care units allow the appearance of symptoms associated with burnout such as stress, irritability, fatigue and emotional instability on health care personnel. The aim of this study was to evaluate the equivalent continuous noise levels in the neonatal intensive care unit and compare the results with noise levels associated with the occurrence of burnout syndrome on the care team. Continuous sampling was conducted for 20 days using a type I sound level meter on the unit. The maximum, the ninetieth percentile and the equivalent continuous noise level (Leq) values were recorded. Noise level is reported in the range of 51.4-77.6 decibels A (dBA) with an average of 64 dBA, 100.6 dBA maximum, and average background noise from 57.9 dBA. Noise levels exceed the standards suggested for neonatal intensive care units, are close to maximum values referred for noise exposure in the occupational standards and to noise levels associated with the onset of burnout; thus allowing to infer the probability of occurrence of high levels of noise present in the unit on the development of burnout in caregivers. Copyright © 2013 Elsevier España, S.L.U. y SEEIUC. All rights reserved.

Acoustic metamaterials capable of both sound insulation and energy harvesting

NASA Astrophysics Data System (ADS)

Li, Junfei; Zhou, Xiaoming; Huang, Guoliang; Hu, Gengkai

2016-04-01

Membrane-type acoustic metamaterials are well known for low-frequency sound insulation. In this work, by introducing a flexible piezoelectric patch, we propose sound-insulation metamaterials with the ability of energy harvesting from sound waves. The dual functionality of the metamaterial device has been verified by experimental results, which show an over 20 dB sound transmission loss and a maximum energy conversion efficiency up to 15.3% simultaneously. This novel property makes the metamaterial device more suitable for noise control applications.

Phenology of the McMurdo Sound Spring Bloom

NASA Astrophysics Data System (ADS)

Daly, K. L.; Kim, S.; Broadbent, H.; Saenz, B.; Ainley, D. G.; Ballard, G.; Pitman, R.; DiTullio, G. R.

2016-02-01

The phenology of spring blooms in most cases has important consequences for the food web that supports upper trophic level predators. An investigation during spring/summer of 2012/13 and 2014/15 of the McMurdo Sound ecosystem, at the southern end of the Ross Sea, revealed that maximum concentrations of fast ice algae occurred during November, with higher concentrations on the eastern side of the Sound near Ross Island and lower concentrations on the western side in the cold water outflow from under the Ross Ice Shelf. In early to mid-December, warming surface water ablated the undersurface of the fast ice and ice algae likely sank rapidly out of the water column to provide food for the benthos. Also in early to mid-December, the McMurdo system transitioned to a phytoplankton bloom at the fast ice edge and under the ice, which co-occurred with the timing of Adelie penguin reproduction (chick hatching) at Cape Royds and the arrival of minke whales and fish-eating killer whales at the fast ice edge. The phytoplankton bloom was initially advected from the Ross Sea into the eastern side of McMurdo Sound and then spread across the Sound to the western side. The phytoplankton community, which was dominated by diatoms and Phaeocystis, was not grazed down by zooplankton and appeared to sink out of the water column. Results support recent findings that a wasp-waist food web structure exists in the Ross Sea, whereby upper trophic levels are not closely coupled to phytoplankton dynamics.

Identification of sleep bruxism with an ambulatory wireless recording system.

PubMed

Inano, Shinji; Mizumori, Takahiro; Kobayashi, Yasuyoshi; Sumiya, Masakazu; Yatani, Hirofumi

2013-01-01

To examine whether an ambulatory bruxism recording system, including a biologic monitor, that measures sleep variables and sympatho-vagal balance can specifically identify sleep bruxism (SB) at home. Twenty-six volunteers, including 16 SB subjects, were recruited. Each participant recorded his or her electromyogram (EMG), sympatho-vagal balance, and sound level for 3 consecutive nights using an audio-video recorder to identify SB. Data of sleep variables were compared among the 3 experimental nights. The episodes were classified into SB episodes with and without grinding and non-SB episodes. EMG patterns, amplitude, sympatho-vagal balance, and sound level of all episodes were analyzed so as to determine the appropriate thresholds to detect SB episodes and grinding sound. Then, all episodes without video-recording data were classified into SB and non-SB episodes by using the appropriate thresholds, and the sensitivity and specificity to detect SB episodes were calculated. With regard to sleep variables, there were no significant differences except for sleep latency between the first and second nights. The appropriate EMG pattern and thresholds of amplitude, sympatho-vagal balance, and sound level were phasic or mixed EMG pattern, 20% of maximum voluntary contraction, mean + 1 SD, and mean + 2 SDs, respectively. The sensitivity and specificity to detect SB episodes were 88.4% and 74.2%, respectively. The results suggest that this system enables the detection of SB episodes at home with considerably high accuracy and little interference with sleep.

Steady-state MEG responses elicited by a sequence of amplitude-modulated short tones of different carrier frequencies.

PubMed

Kuriki, Shinya; Kobayashi, Yusuke; Kobayashi, Takanari; Tanaka, Keita; Uchikawa, Yoshinori

2013-02-01

The auditory steady-state response (ASSR) is a weak potential or magnetic response elicited by periodic acoustic stimuli with a maximum response at about a 40-Hz periodicity. In most previous studies using amplitude-modulated (AM) tones of stimulus sound, long lasting tones of more than 10 s in length were used. However, characteristics of the ASSR elicited by short AM tones have remained unclear. In this study, we examined magnetoencephalographic (MEG) ASSR using a sequence of sinusoidal AM tones of 0.78 s in length with various tone frequencies of 440-990 Hz in about one octave variation. It was found that the amplitude of the ASSR was invariant with tone frequencies when the level of sound pressure was adjusted along an equal-loudness curve. The amplitude also did not depend on the existence of preceding tone or difference in frequency of the preceding tone. When the sound level of AM tones was changed with tone frequencies in the same range of 440-990 Hz, the amplitude of ASSR varied in a proportional manner to the sound level. These characteristics are favorable for the use of ASSR in studying temporal processing of auditory information in the auditory cortex. The lack of adaptation in the ASSR elicited by a sequence of short tones may be ascribed to the neural activity of widely accepted generator of magnetic ASSR in the primary auditory cortex. Copyright © 2012 Elsevier B.V. All rights reserved.

Cochlear transducer operating point adaptation.

PubMed

Zou, Yuan; Zheng, Jiefu; Ren, Tianying; Nuttall, Alfred

2006-04-01

The operating point (OP) of outer hair cell (OHC) mechanotransduction can be defined as any shift away from the center position on the transduction function. It is a dc offset that can be described by percentage of the maximum transduction current or as an equivalent dc pressure in the ear canal. The change of OP can be determined from the changes of the second and third harmonics of the cochlear microphonic (CM) following a calibration of its initial value. We found that the initial OP was dependent on sound level and cochlear sensitivity. From CM generated by a lower sound level at 74 dB SPL to avoid saturation and suppression of basal turn cochlear amplification, the OHC OP was at constant 57% of the maximum transduction current (an ear canal pressure of -0.1 Pa). To perturb the OP, a constant force was applied to the bony shell of the cochlea at the 18 kHz best frequency location using a blunt probe. The force applied over the scala tympani induced an OP change as if the organ of Corti moved toward the scala vestibuli (SV) direction. During an application of the constant force, the second harmonic of the CM partially recovered toward the initial level, which could be described by two time constants. Removing the force induced recovery of the second harmonic to its normal level described by a single time constant. The force applied over the SV caused an opposite result. These data indicate an active mechanism for OHC transduction OP.

Rocket noise - A review

NASA Astrophysics Data System (ADS)

McInerny, S. A.

1990-10-01

This paper reviews what is known about far-field rocket noise from the controlled studies of the late 1950s and 1960s and from launch data. The peak dimensionless frequency, the dependence of overall sound power on exhaust parameters, and the directivity of the overall sound power of rockets are compared to those of subsonic jets and turbo-jets. The location of the dominant sound source in the rocket exhaust plume and the mean flow velocity in this region are discussed and shown to provide a qualitative explanation for the low peak Strouhal number, fD(e)/V(e), and large angle of maximum directivity. Lastly, two empirical prediction methods are compared with data from launches of a Titan family vehicle (two, solid rocket motors of 5.7 x 10 to the 6th N thrust each) and the Saturn V (five, liquid oxygen/rocket propellant engines of 6.7 x 10 to the 6th N thrust, each). The agreement is favorable. In contrast, these methods appear to overpredict the far-field sound pressure levels generated by the Space Shuttle.

Autonomic, endocrine and behavioural responses to thunder in laboratory and companion dogs.

PubMed

Franzini de Souza, Carla Caroline; Maccariello, Carolina Elisabetta Martins; Dias, Daniel Penteado Martins; Almeida, Norma Aparecida Dos Santos; Medeiros, Magda Alves de

2017-02-01

Dogs are highly sensitive to sound stimuli, especially fireworks, firearms, and thunder, and therefore these sounds are used as models of stress reactivity in dogs. Companion and laboratory dogs may respond differently to stressful stimuli, due to differences in management and their relationship with humans. Therefore, the reactivity of beagle dogs (laboratory) and companion dogs to an acute acoustic stress model was studied by analysing the heart rate variability (HRV; cardiac interval values), serum cortisol levels and various behavioural parameters. Eight beagles and six privately owned dogs with no history of phobia to thunder were used. The sound stimulus consisted of a standardized recording of thunder for 2.5min with a maximum intensity of 103-104dB. To evaluate the HRV, cardiac intervals were recorded using a frequency meter (Polar RS800CX model), and later the data were analysed using CardioSeries 2.4.1 software. In both laboratory and companion dogs, thunder promoted an increase in the power of the LF band of the cardiac interval spectrum, in the LF/HF ratio and in the HR, and a decrease in the power of the HF band of the cardiac interval spectrum. Companion dogs showed higher cortisol levels, than beagles, independently of the time point studied and a significant increase in the cortisol levels 15min after acoustic stress, while beagles did not show any alterations in their cortisol levels in response to the sound. On the other hand, beagles showed higher scores in the trembling, hiding, vigilance, running, salivation, bolting and startle parameters than companion dogs. Our results showed that independently of the sound stimulus, companion dogs had higher cortisol levels than laboratory dogs. Furthermore, the sound stimulus induced a marked autonomic imbalance towards sympathetic predominance in both laboratory and companion dogs. However a significant increase in the cortisol was observed only in companion dogs. On the other hand, in general the behavioural response was more pronounced in laboratory dogs than in companion dogs. Copyright © 2016 Elsevier Inc. All rights reserved.

The effect of static force on round window stimulation with the direct acoustic cochlea stimulator.

PubMed

Maier, Hannes; Salcher, Rolf; Schwab, Burkard; Lenarz, Thomas

2013-07-01

The Direct Acoustic Cochlea Stimulator Partial Implant (DACS PI, Phonak Acoustic Implants SA, Switzerland) is intended to stimulate the cochlea by a conventional stapedotomy piston that is crimped onto the DACS PI artificial incus. An alternative approach to the round window (RW) is successfully done with other devices, having the advantage of being also independent of the existence of middle ear structure (e.g. ossicles). Here the possibility of stimulating the RW with the DACS actuator is investigated including the impact of static force on sound transmission to the cochlea. The maximum equivalent sound pressure output with RW stimulation was determined experimentally in fresh human temporal bones. Experiments were performed in analogy to the ASTM standard (F2504.24930-1) method for the output determination of implantable middle ear hearing devices (IMEHDs) in human cadaveric temporal bones (TBs). ASTM compliant temporal bones were stimulated with a prosthesis having a spherical tip (∅0.5 mm) attached to the actuator. The stimulation was performed perpendicular to the round window membrane (RWM) at varying position relative to the RW and the resulting static force on the RW membrane was determined. At each position the displacement output of the DACS PI actuator and the stapes footplate (SFP) vibration in response to actuator stimulation was measured with a Laser Doppler Velocimeter (LDV). By comparison of the achieved output at the stapes footplate in response to sound and transducer stimulation the equivalent sound pressure level at the tympanic membrane at 1Vrms input voltage was calculated assuming that the SFP displacement in both conditions is a measure of perceived loudness, as it is done in the ASTM standard. Ten TB preparations within the acceptance range of the ASTM standard were used for analysis. The actuator driven stapes footplate displacement amplitude as well as the resulting equivalent sound pressure level was highly dependent on the static force applied to the RW. The sound transfer efficiency from the RW to the stapes footplate increased monotonically with increasing static load. At a moderate static force load (approx. 3.9 mN) the obtained average sound equivalent sound pressure level was 102-120 eq. dB SPL @ nominally 1Vrms input for frequencies ≤4 kHz. At higher frequencies (6-10 kHz) the achieved output dropped to ∼90 dB SPL. This output was obtained at loading conditions compatible with the actuator safe operating range, although it was possible to increase the output further by increasing the static force load. Our results demonstrate for a first time that static force applied to the RW is crucial for sound transmission efficiency. Further we could show that RW stimulation with the DACS PI actuator is possible having a maximum output that is sufficient to treat moderate and pronounced sensorineural hearing losses (SNHL). This article is part of a Special Issue entitled "MEMRO 2012". Copyright © 2013 Elsevier B.V. All rights reserved.

Noise Exposure of Teachers in Nursery Schools—Evaluation of Measures for Noise Reduction When Dropping DUPLO Toy Bricks into Storage Cases by Sound Analyses

PubMed Central

Gebauer, Konstanze; Scharf, Thomas; Baumann, Uwe; Groneberg, David A.; Bundschuh, Matthias

2016-01-01

Background: Although noise is one of the leading work-related health risk factors for teachers, many nursery schools lack sufficient noise reduction measures. Methods: This intervention study evaluated the noise exposure of nursery school teachers when dropping DUPLO toy bricks into storage cases. Sound analyses of the impact included assessment of the maximum sound pressure level (LAFmax) as well as frequency analyses with 1/3 octave band filter. For the purpose of standardization, a customized gadget was developed. Recordings were performed in 11 cases of different materials and designs to assess the impact on sound level reduction. Thereby, the acoustic effects of three damping materials (foam rubber, carpet, and PU-foam) were investigated. Results: The lowest LAFmax was measured in cases consisting of “metal grid” (90.71 dB) or of a woven willow “basket” (91.61 dB), whereas a case of “aluminium” (103.34 dB) generated the highest impact LAFmax. The frequency analyses determined especially low LAFmax in the frequency bands between 80 and 2500 Hz in cases designs “metal grid” and “basket”. The insertion of PU-foam achieved the most significant attenuation of LAFmax (−13.88 dB) and, in the frequency analyses, the best sound damping. Conclusion: The dropping of DUPLO bricks in cases contributes to the high noise level in nursery schools, but measured LAFmax show no evidence for the danger of acute hearing loss. However, continuous exposure may lead to functional impairment of the hair cells and trigger stress reactions. We recommend noise reduction by utilizing cases of woven “basket” with an insert of PU-foam. PMID:27384575

Noise Exposure of Teachers in Nursery Schools-Evaluation of Measures for Noise Reduction When Dropping DUPLO Toy Bricks into Storage Cases by Sound Analyses.

PubMed

Gebauer, Konstanze; Scharf, Thomas; Baumann, Uwe; Groneberg, David A; Bundschuh, Matthias

2016-07-04

Although noise is one of the leading work-related health risk factors for teachers, many nursery schools lack sufficient noise reduction measures. This intervention study evaluated the noise exposure of nursery school teachers when dropping DUPLO toy bricks into storage cases. Sound analyses of the impact included assessment of the maximum sound pressure level (LAFmax) as well as frequency analyses with 1/3 octave band filter. For the purpose of standardization, a customized gadget was developed. Recordings were performed in 11 cases of different materials and designs to assess the impact on sound level reduction. Thereby, the acoustic effects of three damping materials (foam rubber, carpet, and PU-foam) were investigated. The lowest LAFmax was measured in cases consisting of "metal grid" (90.71 dB) or of a woven willow "basket" (91.61 dB), whereas a case of "aluminium" (103.34 dB) generated the highest impact LAFmax. The frequency analyses determined especially low LAFmax in the frequency bands between 80 and 2500 Hz in cases designs "metal grid" and "basket". The insertion of PU-foam achieved the most significant attenuation of LAFmax (-13.88 dB) and, in the frequency analyses, the best sound damping. The dropping of DUPLO bricks in cases contributes to the high noise level in nursery schools, but measured LAFmax show no evidence for the danger of acute hearing loss. However, continuous exposure may lead to functional impairment of the hair cells and trigger stress reactions. We recommend noise reduction by utilizing cases of woven "basket" with an insert of PU-foam.

Involuntary and persistent environmental noise influences health and hearing in Beirut, Lebanon.

PubMed

Fooladi, Marjaneh M

2012-01-01

This study was conducted to assess the effects of involuntary and persistent noise exposure on health and hearing among Lebanese adults in Beirut, Lebanon, where people are exposed to noise from construction sites, power generators, honking cars, and motorcycles. Using a descriptive and exploratory design with mixed methods, participants were surveyed, interviewed, and tested for hearing while street noise levels were measured near their residents and work places. Self-reports of 83 Lebanese adult, who lived and worked in Beirut, helped identify common patterns in experiences such as irritability, anger, headaches, and sleep disturbances due to noise annoyance. Of those tested, 30% suffered from high-frequency hearing impairment. Our results showed that environmental sound dB had increased by 12% and sound intensity by 400% above the maximum standard level when compared to the WHO report of 1999. Environmental noise contributes to premature hearing loss and potentiates systemic diseases among Lebanese.

Comparison of SAGE 2 ozone measurements and ozone soundings at Uccle (Belgium) during the period February 1985 to January 1986

NASA Technical Reports Server (NTRS)

Debacker, Hugo; Demuer, Dirk; Veiga, R. E.; Zawodny, J. M.

1994-01-01

The ozone profiles obtained from 24 balloon soundings, at 50 deg 48 min N, 4 deg 21 min E, carried out with the electro-chemical ozonesondes are discussed. The data were used as correlative data to the ozone profiles acquired by the Stratospheric Aerosol and Gas Experiment (SAGE 2). Good agreement was obtained between the two data sets. The difference of percentage between the ozone column density of the mean balloon and SAGE profile is 4.4% in the altitude region between 10 to 26 km. From the statistical analysis it seems that there is a difference between the mean profiles at the level of the ozone maximum and around the 30 km level. Similar results are obtained with an error analysis of both data. The differences between the mean profiles in the lower stratosphere are probably real, and are due to the presence of ozone.

Determination of sound types and source levels of airborne vocalizations by California sea lions, Zalophus californianus, in rehabilitation at the Marine Mammal Center in Sausalito, California

NASA Astrophysics Data System (ADS)

Schwalm, Afton Leigh

California sea lions (Zalophus californianus) are a highly popular and easily recognized marine mammal in zoos, aquariums, circuses, and often seen by ocean visitors. They are highly vocal and gregarious on land. Surprisingly, little research has been performed on the vocalization types, source levels, acoustic properties, and functions of airborne sounds used by California sea lions. This research on airborne vocalizations of California sea lions will advance the understanding of this aspect of California sea lions communication, as well as examine the relationship between health condition and acoustic behavior. Using a PhillipsRTM digital recorder with attached microphone and a calibrated RadioShackRTM sound pressure level meter, acoustical data were recorded opportunistically on California sea lions during rehabilitation at The Marine Mammal Center in Sausalito, CA. Vocalizations were analyzed using frequency, time, and amplitude variables with Raven Pro: Interactive Sound Analysis Software Version 1.4 (The Cornell Lab of Ornithology, Ithaca, NY). Five frequency, three time, and four amplitude variables were analyzed for each vocalization. Differences in frequency, time, and amplitude variables were not significant by sex. The older California sea lion group produced vocalizations that were significantly lower in four frequency variables, significantly longer in two time variables, significantly higher in calibrated maximum and minimum amplitude variables, and significantly lower in frequency at maximum and minimum amplitude compared with pups. Six call types were identified: bark, goat, growl/grumble, bark/grumble, bark/growl, and grumble/moan. The growl/grumble call was higher in dominant beginning, ending, and minimum frequency, as well as in the frequency at maximum amplitude compared with the bark, goat, bark/grumble calls in the first versus last vocalization sample. The goat call was significantly higher in first harmonic interval than any other call type in the all vocalizations sample. The "fate" of a sea lion was categorized as: released, placed at another facility, remained at TMMC, euthanized, or died. To determine if acoustic features could be used to assess the recovery of a pup, the acoustic features of a pup's first recorded vocalization were compared with the frequency, time, and amplitude of the last vocalization recorded (i.e., before it was released or placed at another facility). In addition, all first vocalizations were pooled and all last vocalizations were pooled for acoustic analysis, regardless of their fate. Released pups had shorter duration calls, a greater first harmonic interval, and a higher dominant maximum frequency than either pups that died or pups remaining at TMMC. Released pups had a higher frequency at maximum and minimum amplitude compared to dead and remaining pups. Pups that died had significantly lower dominant ending frequency and a lower dominant minimum frequency than released or remaining pups. These results were supported by other studies on different species of otariids, phocids, and cetaceans. The preliminary analyses presented in this thesis holds promise that with additional data acoustic features of California sea lion airborne vocalizations could indicate sex, age, and possibly health condition or the potential for release.

Noise characterization of oil and gas operations.

PubMed

Radtke, Cameron; Autenrieth, Daniel A; Lipsey, Tiffany; Brazile, William J

2017-08-01

In cooperation with The Colorado Oil and Gas Conservation Commission, researchers at Colorado State University performed area noise monitoring at 23 oil and gas sites throughout Northern Colorado. The goals of this study were to: (1) measure and compare the noise levels for the different phases of oil and gas development sites; (2) evaluate the effectiveness of noise barriers; and (3) determine if noise levels exceeded the Colorado Oil and Gas Conservation Commission noise limits. The four phases of oil and gas development include drilling, hydraulic fracturing, completion and production. Noise measurements were collected using the A- and C-weighted sound scales. Octave band analysis was also performed to characterize the frequency spectra of the noise measurements.  Noise measurements were collected using noise dosimeters and a hand-held sound-level meter at specified distances from the development sites in each cardinal direction. At 350 ft (107 m), drilling, hydraulic fracturing, and completion sites without noise barriers exceeded the maximum permissible noise levels for residential and commercial zones (55 dBA and 60 dBA, respectively). In addition, drilling and hydraulic fracturing sites with noise barriers exceeded the maximum permissible noise level for residential zones (55 dBA). However, during drilling, hydraulic fracturing, and completion operations, oil producers are allowed an exception to the noise permissible limits in that they only must comply with the industrial noise limit (80 dBA). It is stated in Rule 604.c.(2)A. that: "Operations involving pipeline or gas facility installation or maintenance, the use of a drilling rig, completion rig, workover rig, or stimulation is subject to the maximum permissible noise levels for industrial zones (80dBA)." [8] Production sites were within the Colorado Oil and Gas Conservation Commission permissible noise level criteria for all zones. At 350 ft (107 m) from the noise source, all drilling, hydraulic fracturing, and completion sites exceeded 65 dBC.  Current noise wall mitigation strategies reduced noise levels in both the A- and C-weighted scale measurements. However, this reduction in noise was not sufficient to reduce the noise below the residential permissible noise level (55 dBA).

Applying mathematical modeling to create job rotation schedules for minimizing occupational noise exposure.

PubMed

Tharmmaphornphilas, Wipawee; Green, Benjamin; Carnahan, Brian J; Norman, Bryan A

2003-01-01

This research developed worker schedules by using administrative controls and a computer programming model to reduce the likelihood of worker hearing loss. By rotating the workers through different jobs during the day it was possible to reduce their exposure to hazardous noise levels. Computer simulations were made based on data collected in a real setting. Worker schedules currently used at the site are compared with proposed worker schedules from the computer simulations. For the worker assignment plans found by the computer model, the authors calculate a significant decrease in time-weighted average (TWA) sound level exposure. The maximum daily dose that any worker is exposed to is reduced by 58.8%, and the maximum TWA value for the workers is reduced by 3.8 dB from the current schedule.

Environmental Assessment for QSEU116038 - Lower Pattern Altitude at Moody Air Force Base, Georgia

DTIC Science & Technology

2012-04-01

flight rules ( IFR ) overhead flight patterns. The 2,000-foot AGL VFR overhead flight pattern is associated with the previous Moody AFB training mission...EA Environmental Assessment EIS environmental impact statement IFR instrument flight rules Lmax maximum sound level NEPA National Environmental...airspace only (airspace immediately surrounding the Moody AFB airfield) and would not affect instrument flight rules ( IFR ) overhead flight patterns

Potential impacts of discharging tertiary-treated wastewater into Port Royal Sound, South Carolina

USGS Publications Warehouse

Speiran, G.K.; Belval, D.L.

1985-01-01

An assessment of physical characteristics of Port Royal Sound was combined with the results of a dye tracer study and with data collected from a previous environmental study to describe the impact on the water quality from discharging tertiary treated wastewater into the sound. Calculated velocities for the time of maximum velocity in the tidal cycle ranged from 2.32 ft/sec near the bottom to 4.65 ft/sec near the surface of the sound in a cross section in the vicinity of a proposed wastewater outfall. Vertical velocity distributions calculated for the time of maximum velocity were similar at all stations at which velocities were measured except the station in shallow water near the shore. A recent bathymetric chart of the vicinity of the proposed outfall indicates that a bar extends farther along the northern shore of Hilton Head Island than indicated on earlier nautical charts of Port Royal Sound. Continued extension of this bar could alter the impact on water quality from discharge of treated wastewater into the sound. Further study may be needed to monitor changes in the bar if the outfall is located between the bar and Hilton Head Island. Conservative calculations based on the results of the dye tracer study indicate that the discharge of 10.9 million gallons/day of wastewater having concentrations of biochemical oxygen demand and suspended solids of 15 mg/L will result in a maximum cumulative increase in concentrations of biochemical oxygen demand of < 0.01 mg/L and no increase in concentrations of suspended solids at high slack tide in the part of Port Royal Sound most affected by the proposed wastewater discharge. (Author 's abstract)

Annoyance caused by propeller airplane flyover noise

NASA Technical Reports Server (NTRS)

Mccurdy, D. A.; Powell, C. A.

1984-01-01

Laboratory experiments were conducted to provide information on quantifying the annoyance response of people to propeller airplane noise. The items of interest were current noise metrics, tone corrections, duration corrections, critical band corrections, and the effects of engine type, operation type, maximum takeoff weight, blade passage frequency, and blade tip speed. In each experiment, 64 subjects judged the annoyance of recordings of propeller and jet airplane operations presented at d-weighted sound pressure levels of 70, 80, and 90 dB in a testing room which simulates the outdoor acoustic environment. The first experiment examined 11 propeller airplanes with maximum takeoff weights greater than or equal to 5700 kg. The second experiment examined 14 propeller airplanes weighting 5700 kg or less. Five jet airplanes were included in each experiment. For both the heavy and light propeller airplanes, perceived noise level and perceived level (Stevens Mark VII procedure) predicted annoyance better than other current noise metrics.

Measurement of sound pressure and temperature in tissue-mimicking material using an optical fiber Bragg grating sensor.

PubMed

Imade, Keisuke; Kageyama, Takashi; Koyama, Daisuke; Watanabe, Yoshiaki; Nakamura, Kentaro; Akiyama, Iwaki

2016-10-01

The experimental investigation of an optical fiber Bragg grating (FBG) sensor for biomedical application is described. The FBG sensor can be used to measure sound pressure and temperature rise simultaneously in biological tissues exposed to ultrasound. The theoretical maximum values that can be measured with the FBG sensor are 73.0 MPa and 30 °C. In this study, measurement of sound pressure up to 5 MPa was performed at an ultrasound frequency of 2 MHz. A maximum temperature change of 6 °C was measured in a tissue-mimicking material. Values yielded by the FBG sensor agreed with those measured using a thermocouple and a hydrophone. Since this sensor is used to monitor the sound pressure and temperature simultaneously, it can also be used for industrial applications, such as ultrasonic cleaning of semiconductors under controlled temperatures.

Azimuthal sound localization in the European starling (Sturnus vulgaris): I. Physical binaural cues.

PubMed

Klump, G M; Larsen, O N

1992-02-01

The physical measurements reported here test whether the European starling (Sturnus vulgaris) evaluates the azimuth direction of a sound source with a peripheral auditory system composed of two acoustically coupled pressure-difference receivers (1) or of two decoupled pressure receivers (2). A directional pattern of sound intensity in the free-field was measured at the entrance of the auditory meatus using a probe microphone, and at the tympanum using laser vibrometry. The maximum differences in the sound-pressure level measured with the microphone between various speaker positions and the frontal speaker position were 2.4 dB at 1 and 2 kHz, 7.3 dB at 4 kHz, 9.2 dB at 6 kHz, and 10.9 dB at 8 kHz. The directional amplitude pattern measured by laser vibrometry did not differ from that measured with the microphone. Neither did the directional pattern of travel times to the ear. Measurements of the amplitude and phase transfer function of the starling's interaural pathway using a closed sound system were in accord with the results of the free-field measurements. In conclusion, although some sound transmission via the interaural canal occurred, the present experiments support the hypothesis 2 above that the starling's peripheral auditory system is best described as consisting of two functionally decoupled pressure receivers.

Sound reduction management in the neonatal intensive care unit for preterm or very low birth weight infants.

PubMed

Almadhoob, Abdulraoof; Ohlsson, Arne

2015-01-30

Infants in the neonatal intensive care unit (NICU) are subjected to stress, including sound of high intensity. The sound environment in the NICU is louder than most home or office environments and contains disturbing noises of short duration and at irregular intervals. There are competing auditory signals that frequently challenge preterm infants, staff and parents. The sound levels in NICUs often exceed the maximum acceptable level of 45 decibels (dB), recommended by the American Academy of Pediatrics. Hearing impairment is diagnosed in 2% to 10% of preterm infants versus 0.1% of the general paediatric population. Noise may cause apnoea, hypoxaemia, alternation in oxygen saturation, and increased oxygen consumption secondary to elevated heart and respiratory rates and may, therefore, decrease the amount of calories available for growth. Elevated levels of speech are needed to overcome the noisy environment in the NICU, thereby increasing the negative impacts on staff, newborns, and their families. High noise levels are associated with an increased rate of errors and accidents, leading to decreased performance among staff. The aim of interventions included in this review is to reduce sound levels to 45 dB or less. This can be achieved by lowering the sound levels in an entire unit, treating the infant in a section of a NICU, in a 'private' room, or in incubators in which the sound levels are controlled, or reducing the sound levels that reaches the individual infant by using earmuffs or earplugs. By lowering the sound levels that reach the neonate, the resulting stress on the cardiovascular, respiratory, neurological, and endocrine systems can be diminished, thereby promoting growth and reducing adverse neonatal outcomes. Primary objectiveTo determine the effects of sound reduction on growth and long-term neurodevelopmental outcomes of neonates. Secondary objectives1. To evaluate the effects of sound reduction on short-term medical outcomes (bronchopulmonary dysplasia, intraventricular haemorrhage, periventricular leukomalacia, retinopathy of prematurity).2. To evaluate the effects of sound reduction on sleep patterns at three months of age.3. To evaluate the effects of sound reduction on staff performance.4. To evaluate the effects of sound reduction in the neonatal intensive care unit (NICU) on parents' satisfaction with the care. We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL, abstracts from scientific meetings, clinical trials registries (clinicaltrials.gov; controlled-trials.com; and who.int/ictrp), Pediatric Academic Societies Annual meetings 2000 to 2014 (Abstracts2View(TM)), reference lists of identified trials, and reviews to November 2014. Preterm infants (< 32 weeks' postmenstrual age (PMA) or < 1500 g birth weight) cared for in the resuscitation area, during transport, or once admitted to a NICU or a stepdown unit. We performed data collection and analyses according to the Cochrane Neonatal Review Group. One small, high quality study assessing the effects of silicone earplugs versus no earplugs qualified for inclusion. The original inclusion criteria in our protocol stipulated an age of < 48 hours at the time of initiating sound reduction. We made a deviation from our protocol and included this study in which some infants would have been > 48 hours old. There was no significant difference in weight at 34 weeks postmenstrual age (PMA): mean difference (MD) 111 g (95% confidence interval (CI) -151 to 374 g) (n = 23). There was no significant difference in weight at 18 to 22 months corrected age between the groups: MD 0.31 kg, 95% CI -1.53 to 2.16 kg (n = 14). There was a significant difference in Mental Developmental Index (Bayley II) favouring the silicone earplugs group at 18 to 22 months corrected age: MD 14.00, 95% CI 3.13 to 24.87 (n = 12), but not for Psychomotor Development Index (Bayley II) at 18 to 22 months corrected age: MD -2.16, 95% CI -18.44 to 14.12 (n =12). To date, only 34 infants have been enrolled in a randomised controlled trial (RCT) testing the effectiveness of reducing sound levels that reach the infants' ears in the NICU. Based on the small sample size of this single trial, we cannot make any recommendations for clinical practice. Larger, well designed, conducted and reported trials are needed.

Hearing in the Juvenile Green Sea Turtle (Chelonia mydas): A Comparison of Underwater and Aerial Hearing Using Auditory Evoked Potentials

PubMed Central

Piniak, Wendy E. D.; Mann, David A.; Harms, Craig A.; Jones, T. Todd; Eckert, Scott A.

2016-01-01

Sea turtles spend much of their life in aquatic environments, but critical portions of their life cycle, such as nesting and hatching, occur in terrestrial environments, suggesting that it may be important for them to detect sounds in both air and water. In this study we compared underwater and aerial hearing sensitivities in five juvenile green sea turtles (Chelonia mydas) by measuring auditory evoked potential responses to tone pip stimuli. Green sea turtles detected acoustic stimuli in both media, responding to underwater stimuli between 50 and 1600 Hz and aerial stimuli between 50 and 800 Hz, with maximum sensitivity between 200 and 400 Hz underwater and 300 and 400 Hz in air. When underwater and aerial hearing sensitivities were compared in terms of pressure, green sea turtle aerial sound pressure thresholds were lower than underwater thresholds, however they detected a wider range of frequencies underwater. When thresholds were compared in terms of sound intensity, green sea turtle sound intensity level thresholds were 2–39 dB lower underwater particularly at frequencies below 400 Hz. Acoustic stimuli may provide important environmental cues for sea turtles. Further research is needed to determine how sea turtles behaviorally and physiologically respond to sounds in their environment. PMID:27741231

Hearing in the Juvenile Green Sea Turtle (Chelonia mydas): A Comparison of Underwater and Aerial Hearing Using Auditory Evoked Potentials.

PubMed

Piniak, Wendy E D; Mann, David A; Harms, Craig A; Jones, T Todd; Eckert, Scott A

2016-01-01

Sea turtles spend much of their life in aquatic environments, but critical portions of their life cycle, such as nesting and hatching, occur in terrestrial environments, suggesting that it may be important for them to detect sounds in both air and water. In this study we compared underwater and aerial hearing sensitivities in five juvenile green sea turtles (Chelonia mydas) by measuring auditory evoked potential responses to tone pip stimuli. Green sea turtles detected acoustic stimuli in both media, responding to underwater stimuli between 50 and 1600 Hz and aerial stimuli between 50 and 800 Hz, with maximum sensitivity between 200 and 400 Hz underwater and 300 and 400 Hz in air. When underwater and aerial hearing sensitivities were compared in terms of pressure, green sea turtle aerial sound pressure thresholds were lower than underwater thresholds, however they detected a wider range of frequencies underwater. When thresholds were compared in terms of sound intensity, green sea turtle sound intensity level thresholds were 2-39 dB lower underwater particularly at frequencies below 400 Hz. Acoustic stimuli may provide important environmental cues for sea turtles. Further research is needed to determine how sea turtles behaviorally and physiologically respond to sounds in their environment.

Discovery of Sound in the Sea (DOSITS) Website Development

DTIC Science & Technology

2013-03-04

life affect ocean sound levels? • Science of Sound > Sounds in the Sea > How will ocean acidification affect ocean sound levels? • Science of Sound...Science of Sound > Sounds in the Sea > How does shipping affect ocean sound levels? • Science of Sound > Sounds in the Sea > How does marine

Mechanics of the Mammalian Cochlea

PubMed Central

Robles, Luis; Ruggero, Mario A.

2013-01-01

In mammals, environmental sounds stimulate the auditory receptor, the cochlea, via vibrations of the stapes, the innermost of the middle ear ossicles. These vibrations produce displacement waves that travel on the elongated and spirally wound basilar membrane (BM). As they travel, waves grow in amplitude, reaching a maximum and then dying out. The location of maximum BM motion is a function of stimulus frequency, with high-frequency waves being localized to the “base” of the cochlea (near the stapes) and low-frequency waves approaching the “apex” of the cochlea. Thus each cochlear site has a characteristic frequency (CF), to which it responds maximally. BM vibrations produce motion of hair cell stereocilia, which gates stereociliar transduction channels leading to the generation of hair cell receptor potentials and the excitation of afferent auditory nerve fibers. At the base of the cochlea, BM motion exhibits a CF-specific and level-dependent compressive nonlinearity such that responses to low-level, near-CF stimuli are sensitive and sharply frequency-tuned and responses to intense stimuli are insensitive and poorly tuned. The high sensitivity and sharp-frequency tuning, as well as compression and other nonlinearities (two-tone suppression and intermodulation distortion), are highly labile, indicating the presence in normal cochleae of a positive feedback from the organ of Corti, the “cochlear amplifier.” This mechanism involves forces generated by the outer hair cells and controlled, directly or indirectly, by their transduction currents. At the apex of the cochlea, nonlinearities appear to be less prominent than at the base, perhaps implying that the cochlear amplifier plays a lesser role in determining apical mechanical responses to sound. Whether at the base or the apex, the properties of BM vibration adequately account for most frequency-specific properties of the responses to sound of auditory nerve fibers. PMID:11427697

Noise-induced annoyance from transportation noise: short-term responses to a single noise source in a laboratory.

PubMed

Kim, Jaehwan; Lim, Changwoo; Hong, Jiyoung; Lee, Soogab

2010-02-01

An experimental study was performed to compare the annoyances from civil-aircraft noise, military-aircraft noise, railway noise, and road-traffic noise. Two-way within-subjects designs were applied in this research. Fifty-two subjects, who were naive listeners, were given various stimuli with varying levels through a headphone in an anechoic chamber. Regardless of the frequency weighting network, even under the same average energy level, civil-aircraft noise was the most annoying, followed by military-aircraft noise, railway noise, and road-traffic noise. In particular, penalties in the time-averaged, A-weighted sound level (TAL) of about 8, 5, and 5 dB, respectively, were found in the civil-aircraft, military-aircraft, and railway noises. The reason could be clarified through the high-frequency component and the variability in the level. When people were exposed to sounds with the same maximum A-weighted level, a railway bonus of about 3 dB was found. However, transportation noise has been evaluated by the time-averaged A-weighted level in most countries. Therefore, in the present situation, the railway bonus is not acceptable for railway vehicles with diesel-electric engines.

Cycling exercise classes may be bad for your (hearing) health.

PubMed

Sinha, Sumi; Kozin, Elliott D; Naunheim, Matthew R; Barber, Samuel R; Wong, Kevin; Katz, Leanna W; Otero, Tiffany M N; Stefanov-Wagner, Ishmael J M; Remenschneider, Aaron K

2017-08-01

1) Determine feasibility of smartphone-based mobile technology to measure noise exposure; and 2) measure noise exposure in exercise spin classes. Observational Study. The SoundMeter Pro app (Faber Acoustical, Salt Lake City, UT) was installed and calibrated on iPhone and iPod devices in an audiology chamber using an external sound level meter to within 2 dBA of accuracy. Recording devices were placed in the bike cupholders of participants attending spin classes in Boston, Massachusetts (n = 17) and used to measure sound level (A-weighted) and noise dosimetry during exercise according to National Institute for Occupational Safety and Health (NIOSH) guidelines. The average length of exposure was 48.9 ± 1.2 (standard error of the mean) minutes per class. Maximum sound recorded among 17 random classes was 116.7 dBA, which was below the NIOSH instantaneous exposure guideline of 140 dBA. An average of 31.6 ± 3.8 minutes were spent at >100 dBA. This exceeds NIOSH recommendations of 15 minutes of exposure or less at 100 dBA per day. Average noise exposure for one 45-minute class was 8.95 ± 1.2 times the recommended noise exposure dose for an 8-hour workday. Preliminary data shows that randomly sampled cycling classes may have high noise levels with a potential for noise-induced hearing loss. Mobile dosimetry technology may enable users to self-monitor risk to their hearing and actively engage in noise protection measures. NA Laryngoscope, 127:1873-1877, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Noise comparison of two 1.2-pressure-ratio fans with 15 and 42 rotor blades

NASA Technical Reports Server (NTRS)

Woodward, R. P.; Glaser, F. W.; Wazyniak, J. A.

1973-01-01

Two 1.829-m-(6-ft-) diameter fans suitable for a quiet engine for future short-takeoff-and-landing (STOL) aircraft were compared. Both fans were designed for a 1.2 pressure ratio with similar weight flows, thrusts, and tip speeds. The first fan, designated QF-9, had 15 rotor blades and 11 stator blades. The rotor was highly loaded and the tip solidity was less than 1. The QF-9 rotor blades had an adjustable pitch feature which can be used for thrust reversal. The second fan, designated QF-6, operated at a moderate loading with a rotor tip solidity greater than 1. Fan QF-6 had 42 rotor blades and 50 stator blades. The low number of rotor blades for QF-9 reduced the frequency of the blade-passage tone below the range of maximum annoyance. In addition to this difference, the QF-9 fan had a somewhat smaller rotor-stator separation than the QF-6 fan. In terms of sound pressure level and sound power level, QF-9 was the noisier fan, with the power level results for QF-9 being about 1 db above those for QF-6 at equivalent operating points as determined by similar stage pressure ratios. At the same equivalent operating points, the maximum perceived noise along a 152.5-m (500-ft) sideline for QF-9 was about 2.5 PNdb below that for QF-6, which indicated that QF-9 was less objectionable to human hearing.

The ultimate limits of the relativistic rocket equation. The Planck photon rocket

NASA Astrophysics Data System (ADS)

Haug, Espen Gaarder

2017-07-01

In this paper we look at the ultimate limits of a photon propulsion rocket. The maximum velocity for a photon propulsion rocket is just below the speed of light and is a function of the reduced Compton wavelength of the heaviest subatomic particles in the rocket. We are basically combining the relativistic rocket equation with Haug's new insight on the maximum velocity for anything with rest mass. An interesting new finding is that in order to accelerate any subatomic "fundamental" particle to its maximum velocity, the particle rocket basically needs two Planck masses of initial load. This might sound illogical until one understands that subatomic particles with different masses have different maximum velocities. This can be generalized to large rockets and gives us the maximum theoretical velocity of a fully-efficient and ideal rocket. Further, no additional fuel is needed to accelerate a Planck mass particle to its maximum velocity; this also might sound absurd, but it has a very simple and logical solution that is explained in this paper.

Speech processing using maximum likelihood continuity mapping

DOEpatents

Hogden, John E.

2000-01-01

Speech processing is obtained that, given a probabilistic mapping between static speech sounds and pseudo-articulator positions, allows sequences of speech sounds to be mapped to smooth sequences of pseudo-articulator positions. In addition, a method for learning a probabilistic mapping between static speech sounds and pseudo-articulator position is described. The method for learning the mapping between static speech sounds and pseudo-articulator position uses a set of training data composed only of speech sounds. The said speech processing can be applied to various speech analysis tasks, including speech recognition, speaker recognition, speech coding, speech synthesis, and voice mimicry.

Speech processing using maximum likelihood continuity mapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hogden, J.E.

Speech processing is obtained that, given a probabilistic mapping between static speech sounds and pseudo-articulator positions, allows sequences of speech sounds to be mapped to smooth sequences of pseudo-articulator positions. In addition, a method for learning a probabilistic mapping between static speech sounds and pseudo-articulator position is described. The method for learning the mapping between static speech sounds and pseudo-articulator position uses a set of training data composed only of speech sounds. The said speech processing can be applied to various speech analysis tasks, including speech recognition, speaker recognition, speech coding, speech synthesis, and voice mimicry.

Hydrologic and salinity characteristics of Currituck Sound and selected tributaries in North Carolina and Virginia, 1998–99

USGS Publications Warehouse

Caldwell, William Scott

2001-01-01

Data collected at three sites in Currituck Sound and three tributary sites between March 1, 1998, and February 28, 1999, were used to describe hydrologic and salinity characteristics of Currituck Sound. Water levels and salinity were measured at West Neck Creek at Pungo and at Albemarle and Chesapeake Canal near Princess Anne in Virginia, and at Coinjock, Bell Island, Poplar Branch, and Point Harbor in North Carolina. Flow velocity also was measured at the West Neck Creek and Coinjock sites.The maximum water-level range during the study period was observed near the lower midpoint of Currituck Sound at Poplar Branch. Generally, water levels at all sites were highest during March and April, and lowest during November and December. Winds from the south typically produced higher water levels in Currituck Sound, whereas winds from the north typically produced lower water levels. Although wind over Currituck Sound is associated with fluctuations in water level within the sound, other mechanisms, such as the effects of wind on Albemarle Sound and on other water bodies south of Currituck Sound, likely affect low-frequency water-level variations in Currituck Sound.Flow in West Neck Creek ranged from 313 cubic feet per second to the south to -227 cubic feet per second to the north (negative indicates flow to the north). Flow at the Coinjock site ranged from 15,300 cubic feet per second to the south to -11,700 cubic feet per second to the north. Flow was to the south 68 percent of the time at the West Neck Creek site and 44 percent of the time at the Coinjock site. Daily flow volumes were calculated as the sum of the instantaneous flow volumes. The West Neck Creek site had a cumulative flow volume to the south of 7.69 x 108 cubic feet for the period March 1, 1998, to February 28, 1999; the Coinjock site had a cumulative flow volume to the north of -1.33 x 1010 cubic feet for the same study period.Wind direction and speed influence flow at the West Neck Creek and Coinjock sites, whereas precipitation alone has little effect on flow at these sites. Flow at the West Neck Creek site is semidiurnal but is affected by wind direction and speed. Flow to the south (positive flow) was associated with wind speeds averaging more than 15 miles per hour from the northwest; flow to the north (negative flow) was associated with wind speeds averaging more than 15 miles per hour from the south and southwest. Flow at the Coinjock site reacted in a more unpredictable manner and was not affected by winds or tides in the same manner as West Neck Creek, with few tidal characteristics evident in the record.Throughout the study period, maximum salinity exceeded 3.5 parts per thousand at all sites; however, mean and median salinities were below 3.5 parts per thousand at all sites except the Point Harbor site (3.6 and 4.2 parts per thousand, respectively) at the southern end of the sound. Salinities were less than or equal to 3.5 parts per thousand nearly 100 percent of the time at the Bell Island and Poplar Branch sites in Currituck Sound and about 86 percent of the time at the Albemarle and Chesapeake Canal site north of the sound. Salinity at the West Neck Creek and Coinjock sites was less than or equal to 3.5 parts per thousand about 82 percent of the time.During this study, prevailing winds from the north were associated with flow to the south and tended to increase salinity at the West Neck Creek and the Albemarle and Chesapeake Canal sites. Conversely, these same winds tended to decrease salinity at the other sites. Prevailing winds from the south and southwest were associated with flow to the north and tended to increase salinity at the Poplar Branch and Point Harbor sites in Currituck Sound and at the Coinjock site, but these same winds tended to decrease salinity at the West Neck Creek and the Albemarle and Chesapeake Canal sites. The greatest variations in salinity were observed at the northernmost site, West Neck Creek, and thesouthernmost site, Point Harbor. The least variation in salinity was observed at the upper midpoint of the sound at the Bell Island site.Daily salt loads were computed for 364 days at the West Neck Creek site and 348 days at the Coinjock site from March 1, 1998, to February 28, 1999. The cumulative salt load at West Neck Creek was 28,170 tons to the south, and the cumulative salt load at the Coinjock site was -872,750 tons to the north.The cumulative salt load passing the West Neck Creek site during the study period would be 0.01 part per thousand if uniformly distributed throughout the sound (approximately 489,600 acre-feet in North Carolina). If the cumulative salt load passing the Coinjock site were uniformly distributed throughout the sound, the salinity in the sound would be 0.32 part per thousand. The net transport at the West Neck Creek and Coinjock sites indicates inflow of salt into the sound. A constant inflow of freshwater from tributaries and ground-water sources also occurs; however, the net flow volumes from these freshwater sources are not documented, and the significance of these freshwater inflows toward diluting the net import of salt into the sound is beyond the scope of this study.

Acoustic Noise Levels of Dental Equipments and Its Association with Fear and Annoyance Levels among Patients Attending Different Dental Clinic Setups in Jaipur, India

PubMed Central

Ganta, Shravani; Nagaraj, Anup; Pareek, Sonia; Atri, Mansi; Singh, Kushpal; Sidiq, Mohsin

2014-01-01

Background: Noise is a source of pervasive occupational hazard for practicing dentists and the patients. The sources of dental sounds by various dental equipments can pose as a potential hazard to hearing system and add to the annoyance levels of the patients. The aim of the study was to analyze the noise levels from various equipments and evaluate the effect of acoustic noise stimulus on dental fear and annoyance levels among patients attending different dental clinic setups in Jaipur, India. Methodology: The sampling frame comprised of 180 patients, which included 90 patients attending 10 different private clinics and 90 patients attending a Dental College in Jaipur. The levels of Acoustic Noise Stimulus originating from different equipments were determined using a precision sound level meter/decibulometer. Dental fear among patients was measured using Dental Fear Scale (DFS). Results: Statistical analysis was performed using chi square test and unpaired t-test. The mean background noise levels were found to be maximum in the pre-clinical setup/ laboratory areas (69.23+2.20). Females and the patients attending dental college setup encountered more fear on seeing the drill as compared to the patients attending private clinics (p<0.001). Conclusion: The sources of dental sounds can pose as a potential hazard to hearing system. It was analyzed that the environment in the clinics can directly have an effect on the fear and annoyance levels of patients. Hence it is necessary control the noise from various dental equipments to reduce the fear of patients from visiting a dental clinic. PMID:24959512

Effects of Temperature on Sound Production and Auditory Abilities in the Striped Raphael Catfish Platydoras armatulus (Family Doradidae)

PubMed Central

Papes, Sandra; Ladich, Friedrich

2011-01-01

Background Sound production and hearing sensitivity of ectothermic animals are affected by the ambient temperature. This is the first study investigating the influence of temperature on both sound production and on hearing abilities in a fish species, namely the neotropical Striped Raphael catfish Platydoras armatulus. Methodology/Principal Findings Doradid catfishes produce stridulation sounds by rubbing the pectoral spines in the shoulder girdle and drumming sounds by an elastic spring mechanism which vibrates the swimbladder. Eight fish were acclimated for at least three weeks to 22°, then to 30° and again to 22°C. Sounds were recorded in distress situations when fish were hand-held. The stridulation sounds became shorter at the higher temperature, whereas pulse number, maximum pulse period and sound pressure level did not change with temperature. The dominant frequency increased when the temperature was raised to 30°C and the minimum pulse period became longer when the temperature decreased again. The fundamental frequency of drumming sounds increased at the higher temperature. Using the auditory evoked potential (AEP) recording technique, the hearing thresholds were tested at six different frequencies from 0.1 to 4 kHz. The temporal resolution was determined by analyzing the minimum resolvable click period (0.3–5 ms). The hearing sensitivity was higher at the higher temperature and differences were more pronounced at higher frequencies. In general, latencies of AEPs in response to single clicks became shorter at the higher temperature, whereas temporal resolution in response to double-clicks did not change. Conclusions/Significance These data indicate that sound characteristics as well as hearing abilities are affected by temperatures in fishes. Constraints imposed on hearing sensitivity at different temperatures cannot be compensated even by longer acclimation periods. These changes in sound production and detection suggest that acoustic orientation and communication are affected by temperature changes in the neotropical catfish P. armatulus. PMID:22022618

The prediction of en route noise levels for a DC-9 aircraft

NASA Technical Reports Server (NTRS)

Weir, Donald S.

1988-01-01

En route noise for advanced propfan powered aircraft has become an issue of concern for the Federal Aviation Administration. The NASA Aircraft Noise Prediction Program (ANOPP) is used to demonstrate the source noise and propagation effects for an aircraft in level flight up to 35,000 feet altitude. One-third octave band spectra of the source noise, atmospheric absorption loss, and received noise are presented. The predicted maximum A-weighted sound pressure level is compared to measured data from the Aeronautical Research Institute of Sweden. ANOPP is shown to be an effective tool in evaluating the en route noise characteristics of a DC-9 aircraft.

Effect of intracrystalline water on longitudinal sound velocity in tetragonal hen-egg-white lysozyme crystals.

PubMed

Tachibana, M; Koizumi, H; Kojima, K

2004-05-01

Longitudinal sound velocity of tetragonal hen-egg-white (HEW) lysozyme crystals was measured during air drying by ultrasonic pulseecho method. The sound velocity increases with exposure to open air and approaches a constant value. The maximum value is approximately 2900 m/s that is about 1.6 times as much as that of original one before drying. In addition, the sound velocity clearly recovers to original one after immersing the dried crystal in solution. Therefore, the sound velocity in tetragonal HEW lysozyme crystals can be reversibly changed due to dehydration and rehydration. These changes in sound velocity are discussed in the light of water-mediated intramolecular and intermolecular interactions in the crystals.

Effect of intracrystalline water on longitudinal sound velocity in tetragonal hen-egg-white lysozyme crystals

NASA Astrophysics Data System (ADS)

Tachibana, M.; Koizumi, H.; Kojima, K.

2004-05-01

Longitudinal sound velocity of tetragonal hen-egg-white (HEW) lysozyme crystals was measured during air drying by ultrasonic pulseecho method. The sound velocity increases with exposure to open air and approaches a constant value. The maximum value is ˜2900 m/s that is about 1.6 times as much as that of original one before drying. In addition, the sound velocity clearly recovers to original one after immersing the dried crystal in solution. Therefore, the sound velocity in tetragonal HEW lysozyme crystals can be reversibly changed due to dehydration and rehydration. These changes in sound velocity are discussed in the light of water-mediated intramolecular and intermolecular interactions in the crystals.

Risk assessment of aircraft noise on sleep in Montreal.

PubMed

Tétreault, Louis-Francois; Plante, Céline; Perron, Stéphane; Goudreau, Sophie; King, Norman; Smargiassi, Audrey

2012-05-24

Estimate the number of awakenings additional to spontaneous awakenings, induced by the nighttime aircraft movements at an international airport in Montreal, in the population residing nearby in 2009. Maximum sound levels (LAS,max) were derived from aircraft movements using the Integrated Noise Model 7.0b, on a 28 x 28 km grid centred on the airport and with a 0.1 x 0.1 km resolution. Outdoor LAS,max were converted to indoor LAS,max by reducing noise levels by 15 dB(A) or 21 dB(A). For all grid points, LAS,max were transformed into probabilities of additional awakening using a function developed by Basner et al. (2006). The probabilities of additional awakening were linked to estimated numbers of exposed residents for each grid location to assess the number of aircraft-noise-induced awakenings in Montreal. Using a 15 dB(A) sound attenuation, 590 persons would, on average, have one or more additional awakenings per night for the year 2009. In the scenario using a 21 dB(A) sound attenuation, on average, no one would be subjected to one or more additional awakenings per night due to aircraft noise. Using the 2009 flight patterns, our data suggest that a small number of Montreal residents are exposed to noise levels that could induce one or more awakenings additional to spontaneous awakenings per night.

Laser vocal cordectomy fails to effectively reduce respiratory noise in horses with laryngeal hemiplegia.

PubMed

Brown, Jennifer A; Derksen, Frederik J; Stick, John A; Hartmann, William M; Robinson, N Edward

2005-01-01

To report the effect of unilateral laser vocal cordectomy on respiratory noise and airway function in horses with experimentally induced laryngeal hemiplegia (LH). Experimental study. Six Standardbred horses without upper airway abnormalities at rest or during high-speed treadmill exercise. Respiratory sounds and inspiratory trans-upper airway pressure (P(Ui)) were measured before (baseline) and 14 days after induction of LH by left recurrent laryngeal neurectomy, and again 30, 60, 90, and 120 days after endoscopically assisted laser cordectomy of the left vocal cord. Data were collected with the horses exercising on a treadmill at a speed producing maximum heart rate (HR(max)). In horses exercising at HR(max), induction of LH caused a significant increase in P(Ui), sound level (SL), and the sound intensity of formant 2 (F(2)) and 3 (F(3)). The sound intensity of formant 1 (F(1)) was unaffected by induction of LH. Laser vocal cordectomy had no effect on SL, or on the sound intensity of F(1) and F(3). At 30, 60, 90, and 120 days after surgery, P(Ui) and the sound intensity of F(2) were significantly reduced, but these variables remained significantly different from baseline values. Unilateral laser vocal cordectomy did not effectively improve upper airway noise in horses with LH. The procedure decreased upper airway obstruction to the same degree as bilateral ventriculocordectomy. Currently, laser vocal cordectomy cannot be recommended for the treatment of upper airway noise in horses with LH.

Ultrathin thermoacoustic nanobridge loudspeakers from ALD on polyimide

NASA Astrophysics Data System (ADS)

Brown, J. J.; Moore, N. C.; Supekar, O. D.; Gertsch, J. C.; Bright, V. M.

2016-11-01

The recent development of low-temperature (<200 °C) atomic layer deposition (ALD) for fabrication of freestanding nanostructures has enabled consideration of active device design based on engineered ultrathin films. This paper explores audible sound production from thermoacoustic loudspeakers fabricated from suspended tungsten nanobridges formed by ALD. Additionally, this paper develops an approach to lumped-element modeling for design of thermoacoustic nanodevices and relates the near-field plane wave model of individual transducer beams to the far-field spherical wave sound pressure that can be measured with standard experimental techniques. Arrays of suspended nanobridges with 25.8 nm thickness and sizes as small as 17 μm × 2 μm have been fabricated and demonstrated to produce audible sound using the thermoacoustic effect. The nanobridges were fabricated by ALD of 6.5 nm Al2O3 and 19.3 nm tungsten on sacrificial polyimide, with ALD performed at 130 °C and patterned by standard photolithography. The maximum observed loudspeaker sound pressure level (SPL) is 104 dB, measured at 20 kHz, 9.71 W input power, and 1 cm measurement distance, providing a loudspeaker sensitivity value of ∼64.6 dB SPL/1 mW. Sound production efficiency was measured to vary proportional to frequency f 3 and was directly proportional to input power. The devices in this paper demonstrate industrially feasible nanofabrication of thermoacoustic transducers and a sound production mechanism pertinent to submicron-scale device engineering.

Late-Quaternary glaciation and postglacial emergence, southern Eureka Sound, high-Arctic Canada

NASA Astrophysics Data System (ADS)

O Cofaigh, Colm Seamus

Eureka Sound is the inter-island channel separating Ellesmere and Axel Heiberg islands, High Arctic Canada. This thesis reconstructs the glacial and sea level history of southern Eureka Sound through surficial geological mapping, studies of glacial sedimentology and geomorphology, surveying of raised marine shorelines, radiocarbon dating of marine shells and driftwood and surface exposure dating of erratics and bedrock. Granite dispersal trains, shelly till and ice-moulded bedrock record westerly-flow of warm-based, regional ice into Eureka Sound from a source on southeastern Ellesmere Island during the late Wisconsinan. Regional ice was coalescent with local ice domes over Raanes and northern Svendsen peninsulas. Marine limit (dating <=9.2 ka BP; <=9.9 ka cal BP) is inset into the dispersal trains and records early Holocene deglaciation of regional ice. Collectively these data indicate an extensive ice-cover in southern Eureka Sound during the Last Glacial Maximum. Ice-divides were located along the highlands of central Ellesmere and Axel Heiberg islands, from which ice converged on Eureka Sound, and subsequently flowed north and south along the channel. Deglaciation was characterised by a two-step retreat pattern, likely triggered by eustatic sea level rise and abrupt early Holocene warming. Initial break-up and radial retreat of ice in Eureka Sound and the larger fiords, preceded terrestrial stabilisation along coastlines and inner fiords. Location of deglacial depocentres was predominantly controlled by fiord bathymetry. Regionally, two-step deglaciation is reflected by prominent contrasts in glacial geomorphology between the inner and outer parts of many fiords. Glacial sedimentological and geomorphological evidence indicates spatial variation in basal thermal regime between retreating trunk glaciers. Holocene emergence of up to 150 m asl along southern Eureka Sound is recorded by raised marine deltas, beaches and washing limits. Emergence curves exhibit marked contrasts in the form and rate of initial unloading. Isobases drawn on the 8.5 ka shoreline for greater Eureka Sound demonstrate that a cell of highest emergence extends along the length of the channel, and closes in the vicinity of the entrance to Norwegian Bay. The isobase pattern indicates a distinct loading centre over the sound, and in conjunction with glacial geological evidence, suggests that the thickest late Wisconsinan ice lay over the channel.

Enhancement of lung sounds based on empirical mode decomposition and Fourier transform algorithm.

PubMed

Mondal, Ashok; Banerjee, Poulami; Somkuwar, Ajay

2017-02-01

There is always heart sound (HS) signal interfering during the recording of lung sound (LS) signals. This obscures the features of LS signals and creates confusion on pathological states, if any, of the lungs. In this work, a new method is proposed for reduction of heart sound interference which is based on empirical mode decomposition (EMD) technique and prediction algorithm. In this approach, first the mixed signal is split into several components in terms of intrinsic mode functions (IMFs). Thereafter, HS-included segments are localized and removed from them. The missing values of the gap thus produced, is predicted by a new Fast Fourier Transform (FFT) based prediction algorithm and the time domain LS signal is reconstructed by taking an inverse FFT of the estimated missing values. The experiments have been conducted on simulated and recorded HS corrupted LS signals at three different flow rates and various SNR levels. The performance of the proposed method is evaluated by qualitative and quantitative analysis of the results. It is found that the proposed method is superior to the baseline method in terms of quantitative and qualitative measurement. The developed method gives better results compared to baseline method for different SNR levels. Our method gives cross correlation index (CCI) of 0.9488, signal to deviation ratio (SDR) of 9.8262, and normalized maximum amplitude error (NMAE) of 26.94 for 0 dB SNR value. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Measurement and Numerical Calculation of Force on a Particle in a Strong Acoustic Field Required for Levitation

NASA Astrophysics Data System (ADS)

Kozuka, Teruyuki; Yasui, Kyuichi; Tuziuti, Toru; Towata, Atsuya; Lee, Judy; Iida, Yasuo

2009-07-01

Using a standing-wave field generated between a sound source and a reflector, it is possible to trap small objects at nodes of the sound pressure distribution in air. In this study, a sound field generated under a flat or concave reflector was studied by both experimental measurement and numerical calculation. The calculated result agrees well with the experimental data. The maximum force generated between a sound source of 25.0 mm diameter and a concave reflector is 0.8 mN in the experiment. A steel ball of 2.0 mm in diameter was levitated in the sound field in air.

Uplift of the Kenai Peninsula, Alaska, since the 1964 Prince William Sound earthquake

NASA Technical Reports Server (NTRS)

Cohen, Steven; Holdahl, Sandford; Caprette, Douglas; Hilla, Stephen; Safford, Robert; Schultz, Donald

1995-01-01

Using Global Positioning System (GPS) receivers, we reoccupied several leveling benchmarks on the Kenai Peninsula of Alaska which had been surveyed by conventional leveling immediately following the March 27, 1964, Prince William Sound earthquake (M(sub w) = 9.3). By combining the two sets of measurements with a new, high-resolution model of the geoid in the region, we were able to determine the cumulative 1993-1964 postseismic vertical displacement. We find uplift at all of our benchmarks, relative to Seward, Alaska, a point that is stable according to tide gauge data. The maximum uplift of about 1 m occurs near the middle of the peninsula. The region of maximum uplift appears to be shifted northwest relative to the point of maximum coseismic subsidence. If we use tide gauge data at Nikishka and Seward to constrain the vertical motion, then the observed uplift has a trenchward tilt (down to the southeast) as well as an arching component. To explain the observations, we use creep-at-depth models. Most acceptable models require a fault slip of about 2.75 m, although this result is not unique. If the slip has been continuous since the 1964 earthquake, then the average slip rate is nearly 100 mm/yr, twice the plate convergence rate. Comparing the net uplift achieved in 29 years with that observed over 11 years in an adjacent region southeast of Anchorage, Alaska, we conclude that the rate of uplift is decreasing. A further decrease in the uplift rate is expected as the 29-year averaged displacement rate is about twice the plate convergence rate and therefore cannot be sustained over the entire earthquake cycle.

A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

DOE PAGES

Wang, Taiping; Yang, Zhaoqing

2017-03-25

Previously, a major focus of tidal energy studies in Puget Sound were the deep channels such as Admiralty Inlet that have a larger power potential. Our paper focuses on the possibility of extracting tidal energy from minor tidal channels of Puget Sound by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the study site and validated for tidal elevations andmore » currents. Here, we examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. Model results suggest that with the level of energy extraction in the three energy extraction scenarios, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.« less

A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Taiping; Yang, Zhaoqing

Previously, a major focus of tidal energy studies in Puget Sound were the deep channels such as Admiralty Inlet that have a larger power potential. Our paper focuses on the possibility of extracting tidal energy from minor tidal channels of Puget Sound by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the study site and validated for tidal elevations andmore » currents. Here, we examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. Model results suggest that with the level of energy extraction in the three energy extraction scenarios, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.« less

An experimental investigation of thermoacoustic lasers operating in audible frequency range

NASA Astrophysics Data System (ADS)

Kolhe, Sanket Anil

Thermoacoustic lasers convert heat from a high-temperature heat source into acoustic power while rejecting waste heat to a low temperature sink. The working fluids involved can be air or noble gases which are nontoxic and environmentally benign. Simple in construction due to absence of moving parts, thermoacoustic lasers can be employed to achieve generation of electricity at individual homes, water-heating for domestic purposes, and to facilitate space heating and cooling. The possibility of utilizing waste heat or solar energy to run thermoacoustic devices makes them technically promising and economically viable to generate large quantities of acoustic energy. The research presented in this thesis deals with the effects of geometric parameters (stack position, stack length, tube length) associated with a thermoacoustic laser on the output sound wave. The effects of varying input power on acoustic output were also studied. Based on the experiments, optimum operating conditions were identified and qualitative and/or quantitative explanations were provided to justify our observations. It was observed that the maximum sound pressure level was generated for the laser with the stack positioned at a distance of quarter lengths of a resonator from the closed end. Higher sound pressure levels were recorded for the laser with longer stack lengths and longer resonator lengths. Efforts were also made to develop high-frequency thermoacoustic lasers.

Acoustic noise generation by the DOE/NASA MOD-1 wind turbine

NASA Technical Reports Server (NTRS)

Kelley, N. D.

1981-01-01

The results of a series of measurements taken over the past year of the acoustic emissions from the DOE/NASA MOD-1 Wind Turbine show the maximum acoustic energy is concentrated in the low frequency range, often below 100 Hz. The temporal as well as the frequency characteristics of the turbine sounds have been shown to be important since the MOD-1 is capable of radiating both coherent and incoherent noise. The coherent sounds are usually impulsive and are manifested in an averaged frequency domain plot as large numbers of discrete energy bands extending from the blade passage frequency to beyond 50 Hz on occasion. It is these impulsive sounds which are identified as the principal source of the annoyance to a dozen families living within 3 km of the turbine. The source of the coherent noise appears to be the rapid, unsteady blade loads encountered as the blade passes through the wake of the tower structure. Annoying levels are occasionally reached at nearby homes due to the interaction of the low frequency, high energy peaks in the acoustic impulses and the structural modes of the homes as well as by direct radiation outdoors. The peak levels of these impulses can be enhanced or subdued through complete propagation.

Understanding speech when wearing communication headsets and hearing protectors with subband processing.

PubMed

Brammer, Anthony J; Yu, Gongqiang; Bernstein, Eric R; Cherniack, Martin G; Peterson, Donald R; Tufts, Jennifer B

2014-08-01

An adaptive, delayless, subband feed-forward control structure is employed to improve the speech signal-to-noise ratio (SNR) in the communication channel of a circumaural headset/hearing protector (HPD) from 90 Hz to 11.3 kHz, and to provide active noise control (ANC) from 50 to 800 Hz to complement the passive attenuation of the HPD. The task involves optimizing the speech SNR for each communication channel subband, subject to limiting the maximum sound level at the ear, maintaining a speech SNR preferred by users, and reducing large inter-band gain differences to improve speech quality. The performance of a proof-of-concept device has been evaluated in a pseudo-diffuse sound field when worn by human subjects under conditions of environmental noise and speech that do not pose a risk to hearing, and by simulation for other conditions. For the environmental noises employed in this study, subband speech SNR control combined with subband ANC produced greater improvement in word scores than subband ANC alone, and improved the consistency of word scores across subjects. The simulation employed a subject-specific linear model, and predicted that word scores are maintained in excess of 90% for sound levels outside the HPD of up to ∼115 dBA.

Sound Absorption Characteristics of Aluminum Foams Treated by Plasma Electrolytic Oxidation

PubMed Central

Jin, Wei; Liu, Jiaan; Wang, Zhili; Wang, Yonghua; Cao, Zheng; Liu, Yaohui; Zhu, Xianyong

2015-01-01

Open-celled aluminum foams with different pore sizes were fabricated. A plasma electrolytic oxidation (PEO) treatment was applied on the aluminum foams to create a layer of ceramic coating. The sound absorption coefficients of the foams were measured by an impedance tube and they were calculated by a transfer function method. The experimental results show that the sound absorption coefficient of the foam increases gradually with the decrease of pore size. Additionally, when the porosity of the foam increases, the sound absorption coefficient also increases. The PEO coating surface is rough and porous, which is beneficial for improvement in sound absorption. After PEO treatment, the maximum sound absorption of the foam is improved to some extent. PMID:28793653

Development of the sound localization cues in cats

NASA Astrophysics Data System (ADS)

Tollin, Daniel J.

2004-05-01

Cats are a common model for developmental studies of the psychophysical and physiological mechanisms of sound localization. Yet, there are few studies on the development of the acoustical cues to location in cats. The magnitude of the three main cues, interaural differences in time (ITDs) and level (ILDs), and monaural spectral shape cues, vary with location in adults. However, the increasing interaural distance associated with a growing head and pinnae during development will result in cues that change continuously until maturation is complete. Here, we report measurements, in cats aged 1 week to adulthood, of the physical dimensions of the head and pinnae and the localization cues, computed from measurements of directional transfer functions. At 1 week, ILD depended little on azimuth for frequencies <6-7 kHz, maximum ITD was 175 μs, and for sources varying in elevation, a prominent spectral notch was located at higher frequencies than in the older cats. As cats develop, the spectral cues and the frequencies at which ILDs become substantial (>10 dB) shift to lower frequencies, and the maximum ITD increases to nearly 370 μs. Changes in the cues are correlated with the increasing size of the head and pinnae. [Work supported by NIDCD DC05122.

Dynamic Spatial Hearing by Human and Robot Listeners

NASA Astrophysics Data System (ADS)

Zhong, Xuan

This study consisted of several related projects on dynamic spatial hearing by both human and robot listeners. The first experiment investigated the maximum number of sound sources that human listeners could localize at the same time. Speech stimuli were presented simultaneously from different loudspeakers at multiple time intervals. The maximum of perceived sound sources was close to four. The second experiment asked whether the amplitude modulation of multiple static sound sources could lead to the perception of auditory motion. On the horizontal and vertical planes, four independent noise sound sources with 60° spacing were amplitude modulated with consecutively larger phase delay. At lower modulation rates, motion could be perceived by human listeners in both cases. The third experiment asked whether several sources at static positions could serve as "acoustic landmarks" to improve the localization of other sources. Four continuous speech sound sources were placed on the horizontal plane with 90° spacing and served as the landmarks. The task was to localize a noise that was played for only three seconds when the listener was passively rotated in a chair in the middle of the loudspeaker array. The human listeners were better able to localize the sound sources with landmarks than without. The other experiments were with the aid of an acoustic manikin in an attempt to fuse binaural recording and motion data to localize sounds sources. A dummy head with recording devices was mounted on top of a rotating chair and motion data was collected. The fourth experiment showed that an Extended Kalman Filter could be used to localize sound sources in a recursive manner. The fifth experiment demonstrated the use of a fitting method for separating multiple sounds sources.

Neonatal incubators: a toxic sound environment for the preterm infant?*.

PubMed

Marik, Paul E; Fuller, Christopher; Levitov, Alexander; Moll, Elizabeth

2012-11-01

High sound pressure levels may be harmful to the maturing newborn. Current guidelines suggest that the sound pressure levels within a neonatal intensive care unit should not exceed 45 dB(A). It is likely that environmental noise as well as the noise generated by the incubator fan and respiratory equipment may contribute to the total sound pressure levels. Knowledge of the contribution of each component and source is important to develop effective strategies to reduce noise within the incubator. The objectives of this study were to determine the sound levels, sound spectra, and major sources of sound within a modern neonatal incubator (Giraffe Omnibed; GE Healthcare, Helsinki, Finland) using a sound simulation study to replicate the conditions of a preterm infant undergoing high-frequency jet ventilation (Life Pulse, Bunnell, UT). Using advanced sound data acquisition and signal processing equipment, we measured and analyzed the sound level at a dummy infant's ear and at the head level outside the enclosure. The sound data time histories were digitally acquired and processed using a digital Fast Fourier Transform algorithm to provide spectra of the sound and cumulative sound pressure levels (dBA). The simulation was done with the incubator cooling fan and ventilator switched on or off. In addition, tests were carried out with the enclosure sides closed and hood down and then with the enclosure sides open and the hood up to determine the importance of interior incubator reverberance on the interior sound levels With all the equipment off and the hood down, the sound pressure levels were 53 dB(A) inside the incubator. The sound pressure levels increased to 68 dB(A) with all equipment switched on (approximately 10 times louder than recommended). The sound intensity was 6.0 × 10(-8) watts/m(2); this sound level is roughly comparable with that generated by a kitchen exhaust fan on high. Turning the ventilator off reduced the overall sound pressure levels to 64 dB(A) and the sound pressure levels in the low-frequency band of 0 to 100 Hz were reduced by 10 dB(A). The incubator fan generated tones at 200, 400, and 600 Hz that raised the sound level by approximately 2 dB(A)-3 dB(A). Opening the enclosure (with all equipment turned on) reduced the sound levels above 50 Hz by reducing the revereberance within the enclosure. The sound levels, especially at low frequencies, within a modern incubator may reach levels that are likely to be harmful to the developing newborn. Much of the noise is at low frequencies and thus difficult to reduce by conventional means. Therefore, advanced forms of noise control are needed to address this issue.

Teaching Recognition of Normal and Abnormal Heart Sounds Using Computer-Assisted Instruction

ERIC Educational Resources Information Center

Musselman, Eugene E.; Grimes, George M.

1976-01-01

The computer is being used in an innovative manner to teach the recognition of normal and abnormal canine heart sounds at the University of Chicago. Experience thus far indicates that the PLATO program resources allow the maximum development of the student's proficiency in auscultation. (Editor/LBH)

Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system

NASA Technical Reports Server (NTRS)

Huff, Ronald G.

1989-01-01

Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these tests. The maximum overall sound pressure level is generated in the duct downstream of the valve and reached a value of 180 dB at a valve pressure ratio of 2.8. At the higher valve pressure ratios the spectra downstream of the valve is broad banded with its maximum at 1000 Hz.

Striving for Optimum Noise-Decreasing Strategies in Critical Care: Initial Measurements and Observations.

PubMed

Disher, Timothy C; Benoit, Britney; Inglis, Darlene; Burgess, Stacy A; Ellsmere, Barbara; Hewitt, Brenda E; Bishop, Tanya M; Sheppard, Christopher L; Jangaard, Krista A; Morrison, Gavin C; Campbell-Yeo, Marsha L

To identify baseline sound levels, patterns of sound levels, and potential barriers and facilitators to sound level reduction. The study setting was neonatal and pediatric intensive care units in a tertiary care hospital. Participants were staff in both units and parents of currently hospitalized children or infants. One 24-hour sound measurements and one 4-hour sound measurement linked to observed sound events were conducted in each area of the center's neonatal intensive care unit. Two of each measurement type were conducted in the pediatric intensive care unit. Focus groups were conducted with parents and staff. Transcripts were analyzed with descriptive content analysis and themes were compared against results from quantitative measurements. Sound levels exceeded recommended standards at nearly every time point. The most common code was related to talking. Themes from focus groups included the critical care context and sound levels, effects of sound levels, and reducing sound levels-the way forward. Results are consistent with work conducted in other critical care environments. Staff and families realize that high sound levels can be a problem, but feel that the culture and context are not supportive of a quiet care space. High levels of ambient sound suggest that the largest changes in sound levels are likely to come from design and equipment purchase decisions. L10 and Lmax appear to be the best outcomes for measurement of behavioral interventions.

[Acoustic and aerodynamic characteristics of the oesophageal voice].

PubMed

Vázquez de la Iglesia, F; Fernández González, S

2005-12-01

The aim of the study is to determine the physiology and pathophisiology of esophageal voice according to objective aerodynamic and acoustic parameters (quantitative and qualitative parameters). Our subjects were comprised of 33 laryngectomized patients (all male) that underwent aerodynamic, acoustic and perceptual protocol. There is a statistical association between acoustic and aerodynamic qualitative parameters (phonation flow chart type, sound spectrum, perceptual analysis) among quantitative parameters (neoglotic pressure, phonation flow, phonation time, fundamental frequency, maximum intensity sound level, speech rate). Nevertheles, not always such observations bring practical resources to clinical practice. We consider that the facts studied may enable us to add, pragmatically, new resources to the more effective vocal rehabilitation to these patients. The physiology of esophageal voice is well understood by the method we have applied, also seeking for rehabilitation, improving oral communication skills in the laryngectomee population.

Applications of the TIROS-N sounding and cloud motion wind enhancement for the FGGE 'special effort'. [Global Weather Experiment

NASA Technical Reports Server (NTRS)

Atlas, R.

1980-01-01

In January of 1978, a panel of experts recommended that a 'special effort' be made to enhance and edit satellite soundings and cloud tracked winds in data sparse regions. It was felt that these activities would be necessary to obtain maximum benefits from an evaluation of satellite data during the Global Weather Experiment (FGGE). The 'special effort' is being conducted for the two special observing periods of FGGE. More than sixty cases have been selected for enhancement on the basis of meteorological interest. These cases include situations of blocking, cutoff low development, cyclogenesis, and tropical circulations. The sounding data enhancement process consists of supplementing the operational satellite sounding data set with higher resolution soundings in meteorologically active regions, and with new soundings where data voids or soundings of questionable quality exist.

Quantifying loss of acoustic communication space for right whales in and around a U.S. National Marine Sanctuary.

PubMed

Hatch, Leila T; Clark, Christopher W; Van Parijs, Sofie M; Frankel, Adam S; Ponirakis, Dimitri W

2012-12-01

The effects of chronic exposure to increasing levels of human-induced underwater noise on marine animal populations reliant on sound for communication are poorly understood. We sought to further develop methods of quantifying the effects of communication masking associated with human-induced sound on contact-calling North Atlantic right whales (Eubalaena glacialis) in an ecologically relevant area (~10,000 km(2) ) and time period (peak feeding time). We used an array of temporary, bottom-mounted, autonomous acoustic recorders in the Stellwagen Bank National Marine Sanctuary to monitor ambient noise levels, measure levels of sound associated with vessels, and detect and locate calling whales. We related wind speed, as recorded by regional oceanographic buoys, to ambient noise levels. We used vessel-tracking data from the Automatic Identification System to quantify acoustic signatures of large commercial vessels. On the basis of these integrated sound fields, median signal excess (the difference between the signal-to-noise ratio and the assumed recognition differential) for contact-calling right whales was negative (-1 dB) under current ambient noise levels and was further reduced (-2 dB) by the addition of noise from ships. Compared with potential communication space available under historically lower noise conditions, calling right whales may have lost, on average, 63-67% of their communication space. One or more of the 89 calling whales in the study area was exposed to noise levels ≥120 dB re 1 μPa by ships for 20% of the month, and a maximum of 11 whales were exposed to noise at or above this level during a single 10-min period. These results highlight the limitations of exposure-threshold (i.e., dose-response) metrics for assessing chronic anthropogenic noise effects on communication opportunities. Our methods can be used to integrate chronic and wide-ranging noise effects in emerging ocean-planning forums that seek to improve management of cumulative effects of noise on marine species and their habitats. ©2012 Society for Conservation Biology.

Water-surface elevations for the high tide of December 15, 1977, in the Puget Sound region, Washington

USGS Publications Warehouse

Nelson, L.M.

1985-01-01

An unusually high oceanic tide on December 15, 1977, caused flooding of lowlying, nearshore parts of western Washington, including several areas in the Puget Sound region. At Seattle, the December 15 high tide of 14.8 feet above MLLW (mean lower low water datum; 8.55 feet above the National Geodetic Vertical Daltum of 1929, or NGVD) was 0.1 foot higher than the 100-year high tide. At Neah Bay, near the western end of the Straits of Juan de Fuca, however, the high tide of 8.77 feet MLLW (4.55 feet NGVD) on that date was 3.2 feet lower than the 100-year high tide. This study has identified the observed December 15 high-tide elevations at many locations in the Puget Sound region. The observed high tide then was much higher than predicted in most of the Puget Sound region, primarily as the result of a very low barametric pressure. Little damage from wind waves was reported. Elevation profiles for the predicted and observed high tides on December 15 and for several other selected tide levels indicate an increase in the maximum height in the inland direction, except near Port Angeles, and show abrupt changes in tidal elevations at three constrictions - Admiralty Inlet, Tacoma Narrows, and Deception Pass. (USGS)

Evaluation of road traffic noise abatement by vegetation treatment in a 1:10 urban scale model.

PubMed

Jang, Hyung Suk; Lee, Sung Chan; Jeon, Jin Yong; Kang, Jian

2015-12-01

A 1:10 scale of a street canyon and courtyard was constructed to evaluate sound propagation when various vegetation treatments including trees, shrubs, vegetated facades, and green roofs were installed in the urban environment. Noise reductions in the street canyon and courtyard were measured for both single and combined vegetation treatments. Vegetated facades mitigated the overall noise level up to 1.6 dBA in the street canyon, and greening facades were effective to reduce low frequency noise levels below 1 kHz. Trees increased the noise level at high frequency bands to some extent in the street canyon, while the noise level over 1 kHz decreased in the courtyard after installing the street trees. This is because tree crowns diffused and reflected high frequency sounds into the street canyon. Green roofs offered significant noise abatement over 1 kHz in the courtyard, while the vegetated facade was effective to reduce noise levels at low frequencies. In terms of the integrated effects of vegetation treatments, a combined vegetation treatment was less effective than the sum of single treatments in the street canyon. The maximum noise reduction observed for all combinations of vegetation treatments provided 3.4 dBA of insertion loss in the courtyard.

Vertical amplitude phase structure of a low-frequency acoustic field in shallow water

NASA Astrophysics Data System (ADS)

Kuznetsov, G. N.; Lebedev, O. V.; Stepanov, A. N.

2016-11-01

We obtain in integral and analytic form the relations for calculating the amplitude and phase characteristics of an interference structure of orthogonal projections of the oscillation velocity vector in shallow water. For different frequencies and receiver depths, we numerically study the source depth dependences of the effective phase velocities of an equivalent plane wave, the orthogonal projections of the sound pressure phase gradient, and the projections of the oscillation velocity vector. We establish that at low frequencies in zones of interference maxima, independently of source depth, weakly varying effective phase velocity values are observed, which exceed the sound velocity in water by 5-12%. We show that the angles of arrival of the equivalent plane wave and the oscillation velocity vector in the general case differ; however, they virtually coincide in the zone of the interference maximum of the sound pressure under the condition that the horizontal projections of the oscillation velocity appreciably exceed the value of the vertical projection. We give recommendations on using the sound field characteristics in zones with maximum values for solving rangefinding and signal-detection problems.

49 CFR 227.5 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... second or less. Decibel (dB) means a unit of measurement of sound pressure levels. dB(A) means the sound... operate similar equipment under similar conditions. Sound level or Sound pressure level means ten times... an eight-hour time-weighted-average sound level (TWA) of 85 dB(A), or, equivalently, a dose of 50...

Study of double wall panels for use in propeller driven aircraft

NASA Technical Reports Server (NTRS)

Atwal, M.; Bernhard, R.

1984-01-01

Propeller driven aircraft have exhibited high levels of interior noise. Most absorption materials are not effective at low frequencies where maximum noise levels occur. Two panels separated by an air gap are suggested as an alternative means of noise attenuation. This design produces an impedance mismatch where a sound wave travels backwards to the source. The higher the impedance, the higher the reflected soundwave intensity. Two aluminum panels with helium in between and two panels with one being perforated were investigated. Helium increases the transmission loss because of a greater impedance mismatch than air. The transmission loss of the unperforated panel is higher throughout the frequency range tested.

Study of double wall panels for use in propeller driven aircraft

NASA Astrophysics Data System (ADS)

Atwal, M.; Bernhard, R.

1984-05-01

Propeller driven aircraft have exhibited high levels of interior noise. Most absorption materials are not effective at low frequencies where maximum noise levels occur. Two panels separated by an air gap are suggested as an alternative means of noise attenuation. This design produces an impedance mismatch where a sound wave travels backwards to the source. The higher the impedance, the higher the reflected soundwave intensity. Two aluminum panels with helium in between and two panels with one being perforated were investigated. Helium increases the transmission loss because of a greater impedance mismatch than air. The transmission loss of the unperforated panel is higher throughout the frequency range tested.

Sound level exposure of high-risk infants in different environmental conditions.

PubMed

Byers, Jacqueline F; Waugh, W Randolph; Lowman, Linda B

2006-01-01

To provide descriptive information about the sound levels to which high-risk infants are exposed in various actual environmental conditions in the NICU, including the impact of physical renovation on sound levels, and to assess the contributions of various types of equipment, alarms, and activities to sound levels in simulated conditions in the NICU. Descriptive and comparative design. Convenience sample of 134 infants at a southeastern quarternary children's hospital. A-weighted decibel (dBA) sound levels under various actual and simulated environmental conditions. The renovated NICU was, on average, 4-6 dBA quieter across all environmental conditions than a comparable nonrenovated room, representing a significant sound level reduction. Sound levels remained above consensus recommendations despite physical redesign and staff training. Respiratory therapy equipment, alarms, staff talking, and infant fussiness contributed to higher sound levels. Evidence-based sound-reducing strategies are proposed. Findings were used to plan environment management as part of a developmental, family-centered care, performance improvement program and in new NICU planning.

A Bayesian analysis of trends in ozone sounding data series from 9 Nordic stations

NASA Astrophysics Data System (ADS)

Christiansen, Bo; Jepsen, Nis; Larsen, Niels; Korsholm, Ulrik S.

2016-04-01

Ozone soundings from 9 Nordic stations have been homogenized and interpolated to standard pressure levels. The different stations have very different data coverage; the longest period with data is from the end of the 1980ies to 2013. We apply a model which includes both low-frequency variability in form of a polynomial, an annual cycle with harmonics, the possibility for low-frequency variability in the annual amplitude and phasing, and either white noise or AR1 noise. The fitting of the parameters is performed with a Bayesian approach not only giving the posterior mean values but also credible intervals. We find that all stations agree on an well-defined annual cycle in the free troposphere with a relatively confined maximum in the early summer. Regarding the low-frequency variability we find that Scoresbysund, Ny Aalesund, and Sodankyla show similar structures with a maximum near 2005 followed by a decrease. However, these results are only weakly significant. A significant change in the amplitude of the annual cycle was only found for Ny Aalesund. Here the peak-to-peak amplitude changes from 0.9 to 0.8 mhPa between 1995-2000 and 2007-2012. The results are shown to be robust to the different settings of the model parameters (order of the polynomial, number of harmonics in the annual cycle, type of noise, etc). The results are also shown to be characteristic for all pressure levels in the free troposphere.

Resonant tube for measurement of sound absorption in gases at low frequency/pressure ratios

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J.; Griffin, W. A.

1980-01-01

The paper describes a resonant tube for measuring sound absorption in gases, with specific emphasis on the vibrational relaxation peak of N2, over a range of frequency/pressure ratios from 0.1 to 2500 Hz/atm. The experimental background losses measured in argon agree with the theoretical wall losses except at few isolated frequencies. Rigid cavity terminations, external excitation, and a differential technique of background evaluation were used to minimize spurious contributions to the background losses. Room temperature measurements of sound absorption in binary mixtures of N2-CO2 in which both components are excitable resulted in the maximum frequency/pressure ratio in Hz/atm of 0.063 + 123m for the N2 vibrational relaxation peak, where m is mole percent of added CO2; the maximum ratio for the CO2 peak was 34,500 268m where m is mole percent of added N2.

Simulation of Sound Waves Using the Lattice Boltzmann Method for Fluid Flow: Benchmark Cases for Outdoor Sound Propagation

PubMed Central

Salomons, Erik M.; Lohman, Walter J. A.; Zhou, Han

2016-01-01

Propagation of sound waves in air can be considered as a special case of fluid dynamics. Consequently, the lattice Boltzmann method (LBM) for fluid flow can be used for simulating sound propagation. In this article application of the LBM to sound propagation is illustrated for various cases: free-field propagation, propagation over porous and non-porous ground, propagation over a noise barrier, and propagation in an atmosphere with wind. LBM results are compared with solutions of the equations of acoustics. It is found that the LBM works well for sound waves, but dissipation of sound waves with the LBM is generally much larger than real dissipation of sound waves in air. To circumvent this problem it is proposed here to use the LBM for assessing the excess sound level, i.e. the difference between the sound level and the free-field sound level. The effect of dissipation on the excess sound level is much smaller than the effect on the sound level, so the LBM can be used to estimate the excess sound level for a non-dissipative atmosphere, which is a useful quantity in atmospheric acoustics. To reduce dissipation in an LBM simulation two approaches are considered: i) reduction of the kinematic viscosity and ii) reduction of the lattice spacing. PMID:26789631

Simulation of Sound Waves Using the Lattice Boltzmann Method for Fluid Flow: Benchmark Cases for Outdoor Sound Propagation.

PubMed

Salomons, Erik M; Lohman, Walter J A; Zhou, Han

2016-01-01

Propagation of sound waves in air can be considered as a special case of fluid dynamics. Consequently, the lattice Boltzmann method (LBM) for fluid flow can be used for simulating sound propagation. In this article application of the LBM to sound propagation is illustrated for various cases: free-field propagation, propagation over porous and non-porous ground, propagation over a noise barrier, and propagation in an atmosphere with wind. LBM results are compared with solutions of the equations of acoustics. It is found that the LBM works well for sound waves, but dissipation of sound waves with the LBM is generally much larger than real dissipation of sound waves in air. To circumvent this problem it is proposed here to use the LBM for assessing the excess sound level, i.e. the difference between the sound level and the free-field sound level. The effect of dissipation on the excess sound level is much smaller than the effect on the sound level, so the LBM can be used to estimate the excess sound level for a non-dissipative atmosphere, which is a useful quantity in atmospheric acoustics. To reduce dissipation in an LBM simulation two approaches are considered: i) reduction of the kinematic viscosity and ii) reduction of the lattice spacing.

Assessment of transfemoral amputees using a passive microprocessor-controlled knee versus an active powered microprocessor-controlled knee for level walking.

PubMed

Creylman, Veerle; Knippels, Ingrid; Janssen, Paul; Biesbrouck, Evelyne; Lechler, Knut; Peeraer, Louis

2016-12-19

In transfemoral (TF) amputees, the forward propulsion of the prosthetic leg in swing has to be mainly carried out by hip muscles. With hip strength being the strongest predictor to ambulation ability, an active powered knee joint could have a positive influence, lowering hip loading and contributing to ambulation mobility. To assess this, gait of four TF amputees was measured for level walking, first while using a passive microprocessor-controlled prosthetic knee (P-MPK), subsequently while using an active powered microprocessor-controlled prosthetic knee (A-MPK). Furthermore, to assess long-term effects of the use of an A-MPK, a 4-weeks follow-up case study was performed. The kinetics and kinematics of the gait of four TF amputees were assessed while walking with subsequently the P-MPK and the A-MPK. For one amputee, a follow-up study was performed: he used the A-MPK for 4 weeks, his gait was measured weekly. The range of motion of the knee was higher on both the prosthetic and the sound leg in the A-MPK compared to the P-MPK. Maximum hip torque (HT) during early stance increased for the prosthetic leg and decreased for the sound leg with the A-MPK compared to the P-MPK. During late stance, the maximum HT decreased for the prosthetic leg. The difference between prosthetic and sound leg for HT disappeared when using the A-MPK. Also, an increase in stance phase duration was observed. The follow-up study showed an increase in confidence with the A-MPK over time. Results suggested that, partially due to an induced knee flexion during stance, HT can be diminished when walking with the A-MPK compared to the P-MPK. The single case follow-up study showed positive trends indicating that an adaptation time is beneficial for the A-MPK.

Asynchronous behavior of the Antarctic Ice Sheet and local glaciers during and since Termination 1, Salmon Valley, Antarctica

NASA Astrophysics Data System (ADS)

Jackson, Margaret S.; Hall, Brenda L.; Denton, George H.

2018-01-01

The stability of the Antarctic Ice Sheet under future warming remains an open question with broad implications for sea-level prediction and adaptation. In particular, knowledge of whether the ice sheet has the capacity for rapid drawdown or collapse, or whether it can remain stable during periods of warming, is essential for predicting its future behavior. Here we use 55 radiocarbon dates, coupled with geomorphologic mapping, to reconstruct the timing of changes in ice extent and elevation during the last ice-age termination in Salmon Valley, adjacent to McMurdo Sound in the western Ross Sea Embayment. Results indicate that a grounded ice sheet in the Ross Sea Embayment achieved its maximum elevation and extent along the headlands of Salmon Valley at ∼18,000 yr BP, during a period of increasing temperatures and accumulation over the Antarctic continent. This ice remained at or near its maximum on the headlands near the valley mouth until after ∼14,000 yr BP. Removal of grounded Ross Sea ice from Salmon Valley was complete shortly after ∼7900 yr BP, indicating that the grounding line had retreated through southern McMurdo Sound by that time. We suggest the primary driver of Ross Sea ice removal from McMurdo Sound was marine-based, either through basal melting or calving due to sea-level rise. When combined with regional data, the Salmon Valley record suggests that this sector of the Antarctic Ice Sheet did not contribute in a significant way to deglacial meltwater pulses, such as meltwater pulse 1a. In contrast to the Ross Sea ice, our work also shows that local, independent alpine glaciers in Salmon Valley have advanced through the Holocene. Land-terminating glaciers such as these elsewhere in the region show a similar pattern, and may reflect the continued influence of increased accumulation following the termination of the last ice age.

Assessment of noise pollution in and around a sensitive zone in North India and its non-auditory impacts.

PubMed

Khaiwal, Ravindra; Singh, Tanbir; Tripathy, Jaya Prasad; Mor, Suman; Munjal, Sanjay; Patro, Binod; Panda, Naresh

2016-10-01

Noise pollution in hospitals is recognized as a serious health hazard. Considering this, the current study aimed to map the noise pollution levels and to explore the self reported non-auditory effects of noise in a tertiary medical institute. The study was conducted in an 1800-bedded tertiary hospital where 27 sites (outdoor, indoor, road side and residential areas) were monitored for exposure to noise using Sound Level Meter for 24h. A detailed noise survey was also conducted around the sampling sites using a structured questionnaire to understand the opinion of the public regarding the impact of noise on their daily lives. The equivalent sound pressure level (Leq) was found higher than the permissible limits at all the sites both during daytime and night. The maximum equivalent sound pressure level (Lmax) during the day was observed higher (>80dB) at the emergency and around the main entrance of the hospital campus. Almost all the respondents (97%) regarded traffic as the major source of noise. About three-fourths (74%) reported irritation with loud noise whereas 40% of respondents reported headache due to noise. Less than one-third of respondents (29%) reported loss of sleep due to noise and 8% reported hypertension, which could be related to the disturbance caused due to noise. Noise levels in and around the hospital was well above the permissible standards. The recent Global Burden of Disease highlights the increasing risk of non communicable diseases. The non-auditory effects studied in the current work add to the risk factors associated with non communicable diseases. Hence, there is need to address the issue of noise pollution and associated health risks specially for vulnerable population. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Noise in a Laboratory Animal Facility from the Human and Mouse Perspectives

PubMed Central

Reynolds, Randall P; Kinard, Will L; Degraff, Jesse J; Leverage, Ned; Norton, John N

2010-01-01

The current study was performed to understand the level of sound produced by ventilated racks, animal transfer stations, and construction equipment that mice in ventilated cages hear relative to what humans would hear in the same environment. Although the ventilated rack and animal transfer station both produced sound pressure levels above the ambient level within the human hearing range, the sound pressure levels within the mouse hearing range did not increase above ambient noise from either noise source. When various types of construction equipment were used 3 ft from the ventilated rack, the sound pressure level within the mouse hearing range was increased but to a lesser degree for each implement than were the sound pressure levels within the human hearing range. At more distant locations within the animal facility, sound pressure levels from the large jackhammer within the mouse hearing range decreased much more rapidly than did those in the human hearing range, indicating that less of the sound is perceived by mice than by humans. The relatively high proportion of low-frequency sound produced by the shot blaster, used without the metal shot that it normally uses to clean concrete, increased the sound pressure level above the ambient level for humans but did not increase sound pressure levels above ambient noise for mice at locations greater than 3 ft from inside of the cage, where sound was measured. This study demonstrates that sound clearly audible to humans in the animal facility may be perceived to a lesser degree or not at all by mice, because of the frequency content of the sound. PMID:20858361

Efficacy of passive acoustic screening: implications for the design of imager and MR-suite.

PubMed

Moelker, Adriaan; Vogel, Mika W; Pattynama, Peter M T

2003-02-01

To investigate the efficacy of passive acoustic screening in the magnetic resonance (MR) environment by reducing direct and indirect MR-related acoustic noise, both from the patient's and health worker's perspective. Direct acoustic noise refers to sound originating from the inner and outer shrouds of the MR imager, and indirect noise to acoustic reflections from the walls of the MR suite. Sound measurements were obtained inside the magnet bore (patient position) and at the entrance of the MR imager (health worker position). Inner and outer shrouds and walls were lined with thick layers of sound insulation to eliminate the direct and indirect acoustic pathways. Sound pressure levels (SPLs) and octave band frequencies were acquired during various MR imaging sequences at 1.5 T. Inside the magnet bore, direct acoustic noise radiating from the inner shroud was most relevant, with substantial reductions of up to 18.8 dB when using passive screening of the magnetic bore. At the magnet bore entrance, blocking acoustic noise from the outer shroud and reflections showed significant reductions of 4.5 and 2.8 dB, respectively, and 9.4 dB when simultaneously applied. Inner shroud coverage contributed minimally to the overall SPL reduction. Maximum noise reduction by passive acoustic screening can be achieved by reducing direct sound conduction through the inner and outer shrouds. Additional measures to optimize the acoustic properties of the MR suite have only little effect. Copyright 2003 Wiley-Liss, Inc.

Laboratory studies of scales for measuring helicopter noise

NASA Technical Reports Server (NTRS)

Ollerhead, J. B.

1982-01-01

The adequacy of the effective perceived noise level (EPNL) procedure for rating helicopter noise annoyance was investigated. Recordings of 89 helicopters and 30 fixed wing aircraft (CTOL) flyover sounds were rated with respect to annoyance by groups of approximately 40 subjects. The average annoyance scores were transformed to annoyance levels defined as the equally annoying sound levels of a fixed reference sound. The sound levels of the test sounds were measured on various scales, with and without corrections for duration, tones, and impulsiveness. On average, the helicopter sounds were judged equally annoying to CTOL sounds when their duration corrected levels are approximately 2 dB higher. Multiple regression analysis indicated that, provided the helicopter/CTOL difference of about 2 dB is taken into account, the particular linear combination of level, duration, and tone corrections inherent in EPNL is close to optimum. The results reveal no general requirement for special EPNL correction terms to penalize helicopter sounds which are particularly impulsive; impulsiveness causes spectral and temporal changes which themselves adequately amplify conventionally measured sound levels.

The sound of operation and the acoustic attenuation of the Ohmeda Medical Giraffe OmniBed™.

PubMed

Wubben, Stephanie M; Brueggeman, Paul M; Stevens, Dennis C; Helseth, Carol C; Blaschke, Kristen

2011-01-01

The neonatal intensive care unit (NICU) is an environment that provides premature and fragile infants with health provisions needed to make a complete recovery. Premature infants are often born before their auditory systems have had an opportunity to fully mature. Research has shown that the ambient acoustic environment in the NICU exceeds the maximum noise level recommended by the American Academy of Pediatrics, even after measures have been taken to decrease noise levels. The purpose of this study is to evaluate noise levels inside an Ohmeda Medical Giraffe™ OmniBed™, the natural attenuation of the incubator, and the effects of modifications on attenuation and reverberation within the Giraffe TM OmniBed™. The normal operation of the Giraffe™ OmniBed™ is 41.7 dBA which indicates a lower noise of operation than previous studies. The Giraffe™ OmniBed™ naturally attenuates 12 dBA. Leaving an access latch or portal door open causes a statistically significant (P=.001) increase in sound within the bassinet. All modifications in the no-noise and the noise conditions showed a statistically significant (P=.001) drop in L(eq) when compared to baseline.

Behavioral and modeling studies of sound localization in cats: effects of stimulus level and duration

PubMed Central

Ruhland, Janet L.; Yin, Tom C. T.; Tollin, Daniel J.

2013-01-01

Sound localization accuracy in elevation can be affected by sound spectrum alteration. Correspondingly, any stimulus manipulation that causes a change in the peripheral representation of the spectrum may degrade localization ability in elevation. The present study examined the influence of sound duration and level on localization performance in cats with the head unrestrained. Two cats were trained using operant conditioning to indicate the apparent location of a sound via gaze shift, which was measured with a search-coil technique. Overall, neither sound level nor duration had a notable effect on localization accuracy in azimuth, except at near-threshold levels. In contrast, localization accuracy in elevation improved as sound duration increased, and sound level also had a large effect on localization in elevation. For short-duration noise, the performance peaked at intermediate levels and deteriorated at low and high levels; for long-duration noise, this “negative level effect” at high levels was not observed. Simulations based on an auditory nerve model were used to explain the above observations and to test several hypotheses. Our results indicated that neither the flatness of sound spectrum (before the sound reaches the inner ear) nor the peripheral adaptation influences spectral coding at the periphery for localization in elevation, whereas neural computation that relies on “multiple looks” of the spectral analysis is critical in explaining the effect of sound duration, but not level. The release of negative level effect observed for long-duration sound could not be explained at the periphery and, therefore, is likely a result of processing at higher centers. PMID:23657278

Assessing Acoustic Sound Levels Associated with Active Source Seismic Surveys in Shallow Marine Environments

NASA Astrophysics Data System (ADS)

Bohnenstiehl, D. R.; Tolstoy, M.; Thode, A.; Diebold, J. B.; Webb, S. C.

2004-12-01

The potential effect of active source seismic research on marine mammal populations is a topic of increasing concern, and controversy surrounding such operations has begun to impact the planning and permitting of academic surveys [e.g., Malakoff, 2002 Science]. Although no causal relationship between marine mammal strandings and seismic exploration has been proven, any circumstantial evidence must be thoroughly investigated. A 2002 stranding of two beaked whales in the Gulf of California within 50 km of a R/V Ewing seismic survey has been a subject of concern for both marine seismologists and environmentalists. In order to better understand possible received levels for whales in the vicinity of these operations, modeling is combined with ground-truth calibration measurements. A wide-angle parabolic equation model, which is capable of including shear within the sediment and basement layers, is used to generate predictive models of low-frequency transmission loss within the Gulf of California. This work incorporates range-dependent bathymetry, sediment thickness, sound velocity structure and sub-bottom properties. Oceanic sounds speed profiles are derived from the U.S. Navy's seasonal GDEM model and sediment thicknesses are taken from NOAA's worldwide database. The spectral content of the Ewing's 20-airgun seismic array is constrained by field calibration in the spring of 2003 [Tolstoy et al., 2004 GRL], indicating peak energies at frequencies below a few hundred Hz, with energy spectral density showing an approximate power-law decrease at higher frequencies (being ~40 dB below peak at 1 kHz). Transmission loss is estimated along a series of radials extending from multiple positions along the ship's track, with the directivity of the array accounted for by phase-shifting point sources that are scaled by the cube root of the individual airgun volumes. This allows the time-space history of low-frequency received levels to be reconstructed within the Gulf of California. At various times or positions along the ship's track, the predicted mean and maximum sound level in the water column are contoured. By reconstructing the possible positions of the whales during the survey, based on the time of their stranding and reasonable swim velocities, we constrain the sound levels that they may have been subjected to for a series of scenarios. It is hoped that this work will facilitate a better understanding of acoustic propagation during future airgun experiments in similar environments.

A general low frequency acoustic radiation capability for NASTRAN

NASA Technical Reports Server (NTRS)

Everstine, G. C.; Henderson, F. M.; Schroeder, E. A.; Lipman, R. R.

1986-01-01

A new capability called NASHUA is described for calculating the radiated acoustic sound pressure field exterior to a harmonically-excited arbitrary submerged 3-D elastic structure. The surface fluid pressures and velocities are first calculated by coupling a NASTRAN finite element model of the structure with a discretized form of the Helmholtz surface integral equation for the exterior fluid. After the fluid impedance is calculated, most of the required matrix operations are performed using the general matrix manipulation package (DMAP) available in NASTRAN. Far field radiated pressures are then calculated from the surface solution using the Helmholtz exterior integral equation. Other output quantities include the maximum sound pressure levels in each of the three coordinate planes, the rms and average surface pressures and normal velocities, the total radiated power and the radiation efficiency. The overall approach is illustrated and validated using known analytic solutions for submerged spherical shells subjected to both uniform and nonuniform applied loads.

Modeling underwater noise propagation from marine hydrokinetic power devices through a time-domain, velocity-pressure solution

DOE PAGES

Hafla, Erin; Johnson, Erick; Johnson, C. Nathan; ...

2018-06-01

Marine hydrokinetic (MHK) devices generate electricity from the motion of tidal and ocean currents, as well as ocean waves, to provide an additional source of renewable energy available to the United States. These devices are a source of anthropogenic noise in the marine ecosystem and must meet regulatory guidelines that mandate a maximum amount of noise that may be generated. In the absence of measured levels from in situ deployments, a model for predicting the propagation of sound from an array of MHK sources in a real environment is essential. A set of coupled, linearized velocity-pressure equations in the time-domainmore » are derived and presented in this paper, which are an alternative solution to the Helmholtz and wave equation methods traditionally employed. Discretizing these equations on a three-dimensional (3D), finite-difference grid ultimately permits a finite number of complex sources and spatially varying sound speeds, bathymetry, and bed composition. The solution to this system of equations has been parallelized in an acoustic-wave propagation package developed at Sandia National Labs, called Paracousti. This work presents the broadband sound pressure levels from a single source in two-dimensional (2D) ideal and Pekeris wave-guides and in a 3D domain with a sloping boundary. Furthermore, the paper concludes with demonstration of Paracousti for an array of MHK sources in a simple wave-guide.« less

Modeling underwater noise propagation from marine hydrokinetic power devices through a time-domain, velocity-pressure solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hafla, Erin; Johnson, Erick; Johnson, C. Nathan

Marine hydrokinetic (MHK) devices generate electricity from the motion of tidal and ocean currents, as well as ocean waves, to provide an additional source of renewable energy available to the United States. These devices are a source of anthropogenic noise in the marine ecosystem and must meet regulatory guidelines that mandate a maximum amount of noise that may be generated. In the absence of measured levels from in situ deployments, a model for predicting the propagation of sound from an array of MHK sources in a real environment is essential. A set of coupled, linearized velocity-pressure equations in the time-domainmore » are derived and presented in this paper, which are an alternative solution to the Helmholtz and wave equation methods traditionally employed. Discretizing these equations on a three-dimensional (3D), finite-difference grid ultimately permits a finite number of complex sources and spatially varying sound speeds, bathymetry, and bed composition. The solution to this system of equations has been parallelized in an acoustic-wave propagation package developed at Sandia National Labs, called Paracousti. This work presents the broadband sound pressure levels from a single source in two-dimensional (2D) ideal and Pekeris wave-guides and in a 3D domain with a sloping boundary. Furthermore, the paper concludes with demonstration of Paracousti for an array of MHK sources in a simple wave-guide.« less

Arsenic and lead distribution and mobility in lake sediments in the south-central Puget Sound watershed: the long-term impact of a metal smelter in Ruston, Washington, USA.

PubMed

Gawel, James E; Asplund, Jessica A; Burdick, Sarah; Miller, Michelle; Peterson, Shawna M; Tollefson, Amanda; Ziegler, Kara

2014-02-15

The American Smelting and Refining Company (ASARCO) smelter in Ruston, Washington, contaminated the south-central Puget Sound region with heavy metals, including arsenic and lead. Arsenic and lead distribution in surface sediments of 26 lakes is significantly correlated with atmospheric model predictions of contaminant deposition spatially, with concentrations reaching 208 mg/kg As and 1,375 mg/kg Pb. The temporal distribution of these metals in sediment cores is consistent with the years of operation of the ASARCO smelter. In several lakes arsenic and lead levels are highest at the surface, suggesting ongoing inputs or redistribution of contaminants. Moreover, this study finds that arsenic is highly mobile in these urban lakes, with maximum dissolved arsenic concentrations proportional to surface sediment levels and reaching almost 90 μg/L As. With 83% of the lakes in the deposition zone having surface sediments exceeding published "probable effects concentrations" for arsenic and lead, this study provides evidence for possible ongoing environmental health concerns. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of room absorption on human vocal output in multitalker situations.

PubMed

Nijs, Lau; Saher, Konca; den Ouden, Daniël

2008-02-01

People increase their vocal output in noisy environments. This is known as the Lombard effect. The aim of the present study was to measure the effect as a function of the absorption coefficient. The noise source was generated by using other talkers in the room. A-weighted sound levels were measured in a 108 m(3) test room. The number of talkers varied from one to four and the absorption coefficients from 0.12 to 0.64. A model was introduced based on the logarithmic sum of the level found in an anechoic room plus the increasing portion of noise levels up to 80 dB. Results show that the model fits the measurements when a maximum slope of 0.5 dB per 1.0 dB increase in background level is used. Hence Lombard slopes vary from 0.2 dBdB at 50 dB background level to 0.5 dBdB at 80 dB. In addition, both measurements and the model predict a decrease of 5.5 dB per doubling of absorbing area in a room when the number of talkers is constant. Sound pressure levels increase for a doubling of talkers from 3 dB for low densities to 6 dB for dense crowds. Finally, there was correspondence between the model estimation and previous measurements reported in the literature.

Noise Pollution: Do We Need a Solution? An Analysis of Noise in a Cardiac Care Unit.

PubMed

Ryan, Kevin M; Gagnon, Matthew; Hanna, Tyler; Mello, Brad; Fofana, Mustapha; Ciottone, Gregory; Molloy, Michael

2016-08-01

Introduction Hospitals are meant to be places for respite and healing; however, technological advances and reliance on monitoring alarms has led to the environment becoming increasingly noisy. The coronary care unit (CCU), like the emergency department, provides care to ill patients while being vulnerable to noise pollution. The World Health Organization (WHO; Geneva, Switzerland) recommends that for optimum rest and healing, sound levels should average approximately 30 decibels (dB) with maximum readings less than 40 dB. Problem The purpose of this study was to measure and analyze sound levels in three different locations in the CCU, and to review alarm reports in relation to sound levels. Over a one-month period, sound recorders (Extech SDL600; Extech Instruments; Nashua, New Hampshire USA) were placed in three separate locations in the CCU at the West Roxbury Veterans' Administration (VA) Hospital (Roxbury, Massachusetts USA). Sound samples were recorded once per second, stored in Comma Separated Values format for Excel (Microsoft Corporation; Redmond, Washington USA), and then exported to Microsoft Excel. Averages were determined, plotted per hour, and alarm histories were reviewed to determine alarm noise effect on total noise for each location, as well as common alarm occurrences. Patient Room 1 consistently had the lowest average recordings, though all averages were >40 dB, despite decreases between 10:00 pm and 7:00 am. During daytime hours, recordings maintained levels >50 dB. Overnight noise remained above recommended levels 55.25% of the period in Patient Room 1 and 99.61% of the same time period in Patient Room 7. The nurses' station remained the loudest location of all three. Alarms per hour ranged from 20-26 during the day. Alarms per day averaged: Patient Room 1-57.17, Patient Room 7-122.03, and the nurses' station - 562.26. Oxygen saturation alarms accounted for 33.59% of activity, and heart-related (including ST segment and pacemaker) accounted for 49.24% of alarms. The CCU cares for ill patients requiring constant monitoring. Despite advances in technology, measured noise levels for the hospital studied exceeded WHO standards of 40 dB and peaks of 45 dB, even during night hours when patients require rest. Further work is required to reduce noise levels and examine effects on patient satisfaction, clinical outcomes, and length of stay. Ryan KM , Gagnon M , Hanna T , Mello B , Fofana M , Ciottone G , Molloy M . Noise pollution: do we need a solution? An analysis of noise in a cardiac care unit. Prehosp Disaster Med. 2016;31(4):432-435.

Road Traffic Noise Pollution Analysis for Cernavoda City

NASA Astrophysics Data System (ADS)

Manea, L.; Manea, A.; Florea, D.; Tarulescu, S.

2017-10-01

In the present paper was studied the noise pollution in Cernavodă city. The noise measurements were made for nine intersections from different city areas. Noise measurements were taken for three chosen routes with high population density, heavy traffic, commercial and residential buildings. Average, maximum and minimum values were collected and compared with standards. The impact of road traffic noise on the community depends on various factors such as road location and design, land use planning measures, building design, traffic composition, driver behaviour and the relief. In the study area 9 locations are identified to measure noise level. By using sound level meter noise levels are measured at different peak sessions i.e. morning, afternoon and evening. The presented values were collected for evening rush hour.

Level-tolerant duration selectivity in the auditory cortex of the velvety free-tailed bat Molossus molossus.

PubMed

Macías, Silvio; Hernández-Abad, Annette; Hechavarría, Julio C; Kössl, Manfred; Mora, Emanuel C

2015-05-01

It has been reported previously that in the inferior colliculus of the bat Molossus molossus, neuronal duration tuning is ambiguous because the tuning type of the neurons dramatically changes with the sound level. In the present study, duration tuning was examined in the auditory cortex of M. molossus to describe if it is as ambiguous as the collicular tuning. From a population of 174 cortical 104 (60 %) neurons did not show duration selectivity (all-pass). Around 5 % (9 units) responded preferentially to stimuli having longer durations showing long-pass duration response functions, 35 (20 %) responded to a narrow range of stimulus durations showing band-pass duration response functions, 24 (14 %) responded most strongly to short stimulus durations showing short-pass duration response functions and two neurons (1 %) responded best to two different stimulus durations showing a two-peaked duration-response function. The majority of neurons showing short- (16 out of 24) and band-pass (24 out 35) selectivity displayed "O-shaped" duration response areas. In contrast to the inferior colliculus, duration tuning in the auditory cortex of M. molossus appears level tolerant. That is, the type of duration selectivity and the stimulus duration eliciting the maximum response were unaffected by changing sound level.

Scattering of sound by atmospheric turbulence predictions in a refractive shadow zone

NASA Technical Reports Server (NTRS)

Mcbride, Walton E.; Bass, Henry E.; Raspet, Richard; Gilbert, Kenneth E.

1990-01-01

According to ray theory, regions exist in an upward refracting atmosphere where no sound should be present. Experiments show, however, that appreciable sound levels penetrate these so-called shadow zones. Two mechanisms contribute to sound in the shadow zone: diffraction and turbulent scattering of sound. Diffractive effects can be pronounced at lower frequencies but are small at high frequencies. In the short wavelength limit, then, scattering due to turbulence should be the predominant mechanism involved in producing the sound levels measured in shadow zones. No existing analytical method includes turbulence effects in the prediction of sound pressure levels in upward refractive shadow zones. In order to obtain quantitative average sound pressure level predictions, a numerical simulation of the effect of atmospheric turbulence on sound propagation is performed. The simulation is based on scattering from randomly distributed scattering centers ('turbules'). Sound pressure levels are computed for many realizations of a turbulent atmosphere. Predictions from the numerical simulation are compared with existing theories and experimental data.

In-flight acoustic test results for the SR-2 and SR-3 advanced-design propellers

NASA Technical Reports Server (NTRS)

Lasagna, P. L.; Mackall, K. G.; Cohn, R. B.

1983-01-01

Several advanced-design propellers, previously tested in the wind tunnel at the Lewis Research Center, have been tested in flight at the Dryden Flight Research Facility. The flight-test propellers were mounted on a pylon on the top of the fuselage of a JetStar airplane. Acoustic data for the advanced-design SR-2 and SR-3 propellers at Mach numbers to 0.8 and helical-tip Mach numbers to 1.15 are presented; maximum blade-passage frequency sound-pressure levels are also compared.

Prediction of light aircraft interior sound pressure level using the room equation

NASA Technical Reports Server (NTRS)

Atwal, M.; Bernhard, R.

1984-01-01

The room equation is investigated for predicting interior sound level. The method makes use of an acoustic power balance, by equating net power flow into the cabin volume to power dissipated within the cabin using the room equation. The sound power level transmitted through the panels was calculated by multiplying the measured space averaged transmitted intensity for each panel by its surface area. The sound pressure level was obtained by summing the mean square sound pressures radiated from each panel. The data obtained supported the room equation model in predicting the cabin interior sound pressure level.

Aftereffects of Intense Low-Frequency Sound on Spontaneous Otoacoustic Emissions: Effect of Frequency and Level.

PubMed

Jeanson, Lena; Wiegrebe, Lutz; Gürkov, Robert; Krause, Eike; Drexl, Markus

2017-02-01

The presentation of intense, low-frequency (LF) sound to the human ear can cause very slow, sinusoidal oscillations of cochlear sensitivity after LF sound offset, coined the "Bounce" phenomenon. Changes in level and frequency of spontaneous otoacoustic emissions (SOAEs) are a sensitive measure of the Bounce. Here, we investigated the effect of LF sound level and frequency on the Bounce. Specifically, the level of SOAEs was tracked for minutes before and after a 90-s LF sound exposure. Trials were carried out with several LF sound levels (93 to 108 dB SPL corresponding to 47 to 75 phons at a fixed frequency of 30 Hz) and different LF sound frequencies (30, 60, 120, 240 and 480 Hz at a fixed loudness level of 80 phons). At an LF sound frequency of 30 Hz, a minimal sound level of 102 dB SPL (64 phons) was sufficient to elicit a significant Bounce. In some subjects, however, 93 dB SPL (47 phons), the lowest level used, was sufficient to elicit the Bounce phenomenon and actual thresholds could have been even lower. Measurements with different LF sound frequencies showed a mild reduction of the Bounce phenomenon with increasing LF sound frequency. This indicates that the strength of the Bounce not only is a simple function of the spectral separation between SOAE and LF sound frequency but also depends on absolute LF sound frequency, possibly related to the magnitude of the AC component of the outer hair cell receptor potential.

[Preventive effects of sound insulation windows on the indoor noise levels in a street residential building in Beijing].

PubMed

Guo, Bin; Huang, Jing; Guo, Xin-biao

2015-06-18

To evaluate the preventive effects of sound insulation windows on traffic noise. Indoor noise levels of the residential rooms (on both the North 4th ring road side and the campus side) with closed sound insulation windows were measured using the sound level meter, and comparisons with the simultaneously measured outdoor noise levels were made. In addition, differences of indoor noise levels between rooms with closed sound insulation windows and open sound insulation windows were also compared. The average outdoor noise levels of the North 4th ring road was higher than 70 dB(A), which exceeded the limitation stated in the "Environmental Quality Standard for Noise" (GB 3096-2008) in our country. However, with the sound insulation windows closed, the indoor noise levels reduced significantly to the level under 35 dB(A) (P<0.05), which complied with the indoor noise level standards in our country. The closed or open states of the sound insulation windows had significant influence on the indoor noise levels (P<0.05). Compared with the open state of the sound insulation window, when the sound insulation windows were closed, the indoor noise levels reduced 18.8 dB(A) and 8.3 dB(A) in residential rooms facing North 4th ring road side and campus side, respectively. The results indicated that installation of insulation windows had significant noise reduction effects on street residential buildings especially on the rooms facing major traffic roads. Installation of the sound insulation windows has significant preventive effects on indoor noise in the street residential building.

24 CFR 51.106 - Implementation.

Code of Federal Regulations, 2010 CFR

2010-04-01

... day-night average sound level data are not available may be evaluated from NEF or CNEL analyses using.... The day-night average sound level may be estimated from the design hour L10 or Leq values by the.... The Department of Defense uses day-night average sound level based on C-weighted sound level...

The effects of listening environment and earphone style on preferred listening levels of normal hearing adults using an MP3 player.

PubMed

Hodgetts, William E; Rieger, Jana M; Szarko, Ryan A

2007-06-01

The main objective of this study was to determine the influence of listening environment and earphone style on the preferred-listening levels (PLLs) measured in users' ear canals with a commercially-available MP3 player. It was hypothesized that listeners would prefer higher levels with earbud headphones as opposed to over-the-ear headphones, and that the effects would depend on the environment in which the user was listening. A secondary objective was to use the measured PLLs to determine the permissible listening duration to reach 100% daily noise dose. There were two independent variables in this study. The first, headphone style, had three levels: earbud, over-the-ear, and over-the-ear with noise reduction (the same headphones with a noise reduction circuit). The second, environment, also had 3 levels: quiet, street noise and multi-talker babble. The dependent variable was ear canal A-weighted sound pressure level. A 3 x 3 within-subjects repeated-measures ANOVA was used to analyze the data. Thirty-eight normal hearing adults were recruited from the Faculty of Rehabilitation Medicine at the University of Alberta. Each subject listened to the same song and adjusted the level until it "sounded best" to them in each of the 9 conditions. Significant main effects were found for both the headphone style and environment factors. On average, listeners had higher preferred listening levels with the earbud headphones, than with the over-the-ear headphones. When the noise reduction circuit was used with the over-the-ear headphones, the average PLL was even lower. On average, listeners had higher PLLs in street noise than in multi-talker babble and both of these were higher than the PLL for the quiet condition. The interaction between headphone style and environment was also significant. Details of individual contrasts are explored. Overall, PLLs were quite conservative, which would theoretically allow for extended permissible listening durations. Finally, we investigated the maximum output level of the MP3 player in the ear canals of authors 1 and 3 of this paper. Levels were highest with the earbud style, followed by the over-the-ear with noise reduction. The over-the-ear headphone without noise reduction had the lowest maximum output. The majority of MP3 players are sold with the earbud style of headphones. Preferred listening levels are higher with this style of headphone compared to the over-the-ear style. Moreover, as the noise level in the environment increases, earbud users are even more susceptible to background noise and consequently increase the level of the music to overcome this. The result is an increased sound pressure level at the eardrum. However, the levels chosen by our subjects suggest that MP3 listening levels may not be as significant a concern as has been reported recently in the mainstream media.

Apparatus and method for processing Korotkov sounds. [for blood pressure measurement

NASA Technical Reports Server (NTRS)

Golden, D. P., Jr.; Hoffler, G. W.; Wolthuis, R. A. (Inventor)

1974-01-01

A Korotkov sound processor, used in a noninvasive automatic blood measuring system where the brachial artery is occluded by an inflatable cuff, is disclosed. The Korotkoff sound associated with the systolic event is determined when the ratio of the absolute value of a voltage signal, representing Korotkov sounds in the range of 18 to 26 Hz to a maximum absolute peak value of the unfiltered signals, first equals or exceeds a value of 0.45. Korotkov sound associated with the diastolic event is determined when a ratio of the voltage signal of the Korotkov sounds in the range of 40 to 60 Hz to the absolute peak value of such signals within a single measurement cycle first falls below a value of 0.17. The processor signals the occurrence of the systolic and diastolic events and these signals can be used to control a recorder to record pressure values for these events.

A Mixed-Methods Trial of Broad Band Noise and Nature Sounds for Tinnitus Therapy: Group and Individual Responses Modeled under the Adaptation Level Theory of Tinnitus.

PubMed

Durai, Mithila; Searchfield, Grant D

2017-01-01

Objectives: A randomized cross-over trial in 18 participants tested the hypothesis that nature sounds, with unpredictable temporal characteristics and high valence would yield greater improvement in tinnitus than constant, emotionally neutral broadband noise. Study Design: The primary outcome measure was the Tinnitus Functional Index (TFI). Secondary measures were: loudness and annoyance ratings, loudness level matches, minimum masking levels, positive and negative emotionality, attention reaction and discrimination time, anxiety, depression and stress. Each sound was administered using MP3 players with earbuds for 8 continuous weeks, with a 3 week wash-out period before crossing over to the other treatment sound. Measurements were undertaken for each arm at sound fitting, 4 and 8 weeks after administration. Qualitative interviews were conducted at each of these appointments. Results: From a baseline TFI score of 41.3, sound therapy resulted in TFI scores at 8 weeks of 35.6; broadband noise resulted in significantly greater reduction (8.2 points) after 8 weeks of sound therapy use than nature sounds (3.2 points). The positive effect of sound on tinnitus was supported by secondary outcome measures of tinnitus, emotion, attention, and psychological state, but not interviews. Tinnitus loudness level match was higher for BBN at 8 weeks; while there was little change in loudness level matches for nature sounds. There was no change in minimum masking levels following sound therapy administration. Self-reported preference for one sound over another did not correlate with changes in tinnitus. Conclusions: Modeled under an adaptation level theory framework of tinnitus perception, the results indicate that the introduction of broadband noise shifts internal adaptation level weighting away from the tinnitus signal, reducing tinnitus magnitude. Nature sounds may modify the affective components of tinnitus via a secondary, residual pathway, but this appears to be less important for sound effectiveness. The different rates of adaptation to broadband noise and nature sound by the auditory system may explain the different tinnitus loudness level matches. In addition to group effects there also appears to be a great deal of individual variation. A sound therapy framework based on adaptation level theory is proposed that accounts for individual variation in preference and response to sound. Clinical Trial Registration: www.anzctr.org.au, identifier #12616000742471.

A Mixed-Methods Trial of Broad Band Noise and Nature Sounds for Tinnitus Therapy: Group and Individual Responses Modeled under the Adaptation Level Theory of Tinnitus

PubMed Central

Durai, Mithila; Searchfield, Grant D.

2017-01-01

Objectives: A randomized cross-over trial in 18 participants tested the hypothesis that nature sounds, with unpredictable temporal characteristics and high valence would yield greater improvement in tinnitus than constant, emotionally neutral broadband noise. Study Design: The primary outcome measure was the Tinnitus Functional Index (TFI). Secondary measures were: loudness and annoyance ratings, loudness level matches, minimum masking levels, positive and negative emotionality, attention reaction and discrimination time, anxiety, depression and stress. Each sound was administered using MP3 players with earbuds for 8 continuous weeks, with a 3 week wash-out period before crossing over to the other treatment sound. Measurements were undertaken for each arm at sound fitting, 4 and 8 weeks after administration. Qualitative interviews were conducted at each of these appointments. Results: From a baseline TFI score of 41.3, sound therapy resulted in TFI scores at 8 weeks of 35.6; broadband noise resulted in significantly greater reduction (8.2 points) after 8 weeks of sound therapy use than nature sounds (3.2 points). The positive effect of sound on tinnitus was supported by secondary outcome measures of tinnitus, emotion, attention, and psychological state, but not interviews. Tinnitus loudness level match was higher for BBN at 8 weeks; while there was little change in loudness level matches for nature sounds. There was no change in minimum masking levels following sound therapy administration. Self-reported preference for one sound over another did not correlate with changes in tinnitus. Conclusions: Modeled under an adaptation level theory framework of tinnitus perception, the results indicate that the introduction of broadband noise shifts internal adaptation level weighting away from the tinnitus signal, reducing tinnitus magnitude. Nature sounds may modify the affective components of tinnitus via a secondary, residual pathway, but this appears to be less important for sound effectiveness. The different rates of adaptation to broadband noise and nature sound by the auditory system may explain the different tinnitus loudness level matches. In addition to group effects there also appears to be a great deal of individual variation. A sound therapy framework based on adaptation level theory is proposed that accounts for individual variation in preference and response to sound. Clinical Trial Registration: www.anzctr.org.au, identifier #12616000742471. PMID:28337139

A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Taiping; Yang, Zhaoqing

Previous tidal energy projects in Puget Sound have focused on major deep channels such as Admiralty Inlet that have a larger power potential but pose greater technical challenges than minor tidal channels connecting to small sub-basins. This paper focuses on the possibility of extracting energy from minor tidal channels by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the studymore » site and calibrated for tidal elevations and currents. We examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. The model suggests that with the proposed level of energy extraction, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.« less

40 CFR 201.22 - Measurement instrumentation.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Criteria § 201.22 Measurement instrumentation. (a) A sound level meter or alternate sound level measurement...., 1430 Broadway, New York, NY 10018. Table 1—Sound Level Corrections When Using a Type 2 (or S2A... the sound level meter or (2) the manufacturer of the microphone. The choice of both devices must be...

40 CFR 201.22 - Measurement instrumentation.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Criteria § 201.22 Measurement instrumentation. (a) A sound level meter or alternate sound level measurement...., 1430 Broadway, New York, NY 10018. Table 1—Sound Level Corrections When Using a Type 2 (or S2A... the sound level meter or (2) the manufacturer of the microphone. The choice of both devices must be...

Noise level in a pediatric intensive care unit.

PubMed

Carvalho, Werther B; Pedreira, Mavilde L G; de Aguiar, Maria Augusta L

2005-01-01

The purpose of this study was to verify the noise level at a PICU. This prospective observational study was performed in a 10 bed PICU at a teaching hospital located in a densely populated district within the city of São Paulo, Brazil. Sound pressure levels (dBA) were measured 24 hours during a 6-day period. Noise recording equipment was placed in the PICU access corridor, nursing station, two open wards with three and five beds, and in isolation rooms. The resulting curves were analyzed. A basal noise level variation between 60 and 70 dBA was identified, with a maximum level of 120 dBA. The most significant noise levels were recorded during the day and were produced by the staff. The basal noise level identified exceeds International Noise Council recommendations. Education regarding the effects of noise on human hearing and its relation to stress is the essential basis for the development of a noise reduction program.

Sound absorption by subwavelength membrane structures: A geometric perspective

NASA Astrophysics Data System (ADS)

Yang, Min; Li, Yong; Meng, Chong; Fu, Caixing; Mei, Jun; Yang, Zhiyu; Sheng, Ping

2015-12-01

Decorated membranes comprising a thin layer of elastic film with small rigid platelets fixed on top have been found to be efficient absorbers of low-frequency sound. In this work we consider the problem of sound absorption from a perspective aimed at deriving upper bounds under different scenarios, i.e., whether the sound is incident from one side only or from both sides, and whether there is a reflecting surface on the back side of the membrane. By considering the negligible thickness of the membrane, usually on the order of a fraction of one millimeter, we derive a relation showing that the sum of the incoming sound waves' (complex) pressure amplitudes, averaged over the area of the membrane, must be equal to that of the outgoing waves. By using this relation, and without going to any details of the wave solutions, it is shown that the maximum absorption achievable from one-sided incidence is 50%, while the maximum absorption with a back-reflecting surface can reach 100%. The latter was attained by the hybridized resonances. All the results are shown to be in excellent agreement with the experiments. This generalized perspective, when used together with the Green function's formalism, can be useful in gaining insights into the constraints on what are achievable in scatterings and absorption by thin film structures and delineating them.

Serial profiles of electrostatic potential in five New Mexico thunderstorms

NASA Astrophysics Data System (ADS)

Stolzenburg, Maribeth; Marshall, Thomas C.

2008-07-01

Profiles of electric potential (V) integrated from balloon-borne electric field (E) measurements are used to investigate the electrical evolution of thunderstorms over the mountains in central New Mexico. With sequential soundings through multiple storms, the time skew associated with obtaining V from a noninstantaneous sounding is also studied. The data show that a basic V profile, with a maximum above a minimum, forms in the early stage of the storm and is maintained throughout its mature stage. Series of soundings from individual storms show only a gradual evolution in the V profile from the early through the mature stage, as the extrema descend in altitude and become shallower and vertically closer together. More evolution occurs in the late stage, when the shape of the V profile reverses to have a minimum above a maximum. The 17 V(z) profiles from the mature stage of five different storms are also very similar in overall shape, suggesting that the basic shape is not significantly affected by differences in lightning flash rate among these storms. The findings indicate that the potential profile during a typical sounding in the mature stage is relatively stable, and the overall shape of the mature stage V profile does not change markedly on the time scale of a particular balloon sounding (10-30 min) through New Mexico mountain storms. Thus time-skew problems in the V profiles are minor during a storm's mature stage.

Prospective cohort study on noise levels in a pediatric cardiac intensive care unit.

PubMed

Garcia Guerra, Gonzalo; Joffe, Ari R; Sheppard, Cathy; Pugh, Jodie; Moez, Elham Khodayari; Dinu, Irina A; Jou, Hsing; Hartling, Lisa; Vohra, Sunita

2018-04-01

To describe noise levels in a pediatric cardiac intensive care unit, and to determine the relationship between sound levels and patient sedation requirements. Prospective observational study at a pediatric cardiac intensive care unit (PCICU). Sound levels were measured continuously in slow A weighted decibels dB(A) with a sound level meter SoundEarPro® during a 4-week period. Sedation requirement was assessed using the number of intermittent (PRNs) doses given per hour. Analysis was conducted with autoregressive moving average models and the Granger test for causality. 39 children were included in the study. The average (SD) sound level in the open area was 59.4 (2.5) dB(A) with a statistically significant but clinically unimportant difference between day/night hours (60.1 vs. 58.6; p-value < 0.001). There was no significant difference between sound levels in the open area/single room (59.4 vs. 60.8, p-value = 0.108). Peak noise levels were > 90 dB. There was a significant association between average (p-value = 0.030) and peak sound levels (p-value = 0.006), and number of sedation PRNs. Sound levels were above the recommended values with no differences between day/night or open area/single room. High sound levels were significantly associated with sedation requirements. Copyright © 2017 Elsevier Inc. All rights reserved.

Experimental Research into Noise Emission of A Gear Micropump with Plastic Rotor

NASA Astrophysics Data System (ADS)

Rodionov, L. V.; Rekadze, P. D.

2018-01-01

The previous researches show that it’s possible to replace several parts of gear pump to plastic ones. This substitution leads to cost and noise reduction of the pump. Therefore, the series of acoustic experiments on a test bench were carry-out. Sound pressure levels were recorded with microphone, located in a pipe made of a vacuum rubber. Conducted experiment shows that acoustic characteristics of the micropump depend on the different material of driven rotor. Experimental result indicates that the proposed measures for replacing metal rotor to plastic one reduce micropump noise on the studied modes. The maximum achieved acoustic efficiency on equivalent level is 11 dB.

An avoidance behavior model for migrating whale populations

NASA Astrophysics Data System (ADS)

Buck, John R.; Tyack, Peter L.

2003-04-01

A new model is presented for the avoidance behavior of migrating marine mammals in the presence of a noise stimulus. This model assumes that each whale will adjust its movement pattern near a sound source to maintain its exposure below its own individually specific maximum received sound-pressure level, called its avoidance threshold. The probability distribution function (PDF) of this avoidance threshold across individuals characterizes the migrating population. The avoidance threshold PDF may be estimated by comparing the distribution of migrating whales during playback and control conditions at their closest point of approach to the sound source. The proposed model was applied to the January 1998 experiment which placed a single acoustic source from the U.S. Navy SURTASS-LFA system in the migration corridor of grey whales off the California coast. This analysis found that the median avoidance threshold for this migrating grey whale population was 135 dB, with 90% confidence that the median threshold was within +/-3 dB of this value. This value is less than the 141 dB value for 50% avoidance obtained when the 1984 ``Probability of Avoidance'' model of Malme et al.'s was applied to the same data. [Work supported by ONR.

Acoustic analysis in Mudejar-Gothic churches: Experimental results

NASA Astrophysics Data System (ADS)

Galindo, Miguel; Zamarreño, Teófilo; Girón, Sara

2005-05-01

This paper describes the preliminary results of research work in acoustics, conducted in a set of 12 Mudejar-Gothic churches in the city of Seville in the south of Spain. Despite common architectural style, the churches feature individual characteristics and have volumes ranging from 3947 to 10 708 m3. Acoustic parameters were measured in unoccupied churches according to the ISO-3382 standard. An extensive experimental study was carried out using impulse response analysis through a maximum length sequence measurement system in each church. It covered aspects such as reverberation (reverberation times, early decay times), distribution of sound levels (sound strength); early to late sound energy parameters derived from the impulse responses (center time, clarity for speech, clarity, definition, lateral energy fraction), and speech intelligibility (rapid speech transmission index), which all take both spectral and spatial distribution into account. Background noise was also measured to obtain the NR indices. The study describes the acoustic field inside each temple and establishes a discussion for each one of the acoustic descriptors mentioned by using the theoretical models available and the principles of architectural acoustics. Analysis of the quality of the spaces for music and speech is carried out according to the most widespread criteria for auditoria. .

Acoustic analysis in Mudejar-Gothic churches: experimental results.

PubMed

Galindo, Miguel; Zamarreño, Teófilo; Girón, Sara

2005-05-01

This paper describes the preliminary results of research work in acoustics, conducted in a set of 12 Mudejar-Gothic churches in the city of Seville in the south of Spain. Despite common architectural style, the churches feature individual characteristics and have volumes ranging from 3947 to 10 708 m3. Acoustic parameters were measured in unoccupied churches according to the ISO-3382 standard. An extensive experimental study was carried out using impulse response analysis through a maximum length sequence measurement system in each church. It covered aspects such as reverberation (reverberation times, early decay times), distribution of sound levels (sound strength); early to late sound energy parameters derived from the impulse responses (center time, clarity for speech, clarity, definition, lateral energy fraction), and speech intelligibility (rapid speech transmission index), which all take both spectral and spatial distribution into account. Background noise was also measured to obtain the NR indices. The study describes the acoustic field inside each temple and establishes a discussion for each one of the acoustic descriptors mentioned by using the theoretical models available and the principles of architectural acoustics. Analysis of the quality of the spaces for music and speech is carried out according to the most widespread criteria for auditoria.

Multiple sound source localization using gammatone auditory filtering and direct sound componence detection

NASA Astrophysics Data System (ADS)

Chen, Huaiyu; Cao, Li

2017-06-01

In order to research multiple sound source localization with room reverberation and background noise, we analyze the shortcomings of traditional broadband MUSIC and ordinary auditory filtering based broadband MUSIC method, then a new broadband MUSIC algorithm with gammatone auditory filtering of frequency component selection control and detection of ascending segment of direct sound componence is proposed. The proposed algorithm controls frequency component within the interested frequency band in multichannel bandpass filter stage. Detecting the direct sound componence of the sound source for suppressing room reverberation interference is also proposed, whose merits are fast calculation and avoiding using more complex de-reverberation processing algorithm. Besides, the pseudo-spectrum of different frequency channels is weighted by their maximum amplitude for every speech frame. Through the simulation and real room reverberation environment experiments, the proposed method has good performance. Dynamic multiple sound source localization experimental results indicate that the average absolute error of azimuth estimated by the proposed algorithm is less and the histogram result has higher angle resolution.

Prediction on the Enhancement of the Impact Sound Insulation to a Floating Floor with Resilient Interlayer

NASA Astrophysics Data System (ADS)

Huang, Xianfeng; Meng, Yao; Huang, Riming

2017-10-01

This paper describes a theoretical method for predicting the improvement of the impact sound insulation to a floating floor with the resilient interlayer. Statistical energy analysis (SEA) model, which is skilful in calculating the floor impact sound, is set up for calculating the reduction in impact sound pressure level in downstairs room. The sound transmission paths which include direct path and flanking paths are analyzed to find the dominant one; the factors that affect impact sound reduction for a floating floor are explored. Then, the impact sound level in downstairs room is determined and comparisons between predicted and measured data are conducted. It is indicated that for the impact sound transmission across a floating floor, the flanking path impact sound level contribute tiny influence on overall sound level in downstairs room, and a floating floor with low stiffness interlayer exhibits favorable sound insulation on direct path. The SEA approach applies to the floating floors with resilient interlayers, which are experimentally verified, provides a guidance in sound insulation design.

Sound levels and their effects on children in a German primary school.

PubMed

Eysel-Gosepath, Katrin; Daut, Tobias; Pinger, Andreas; Lehmacher, Walter; Erren, Thomas

2012-12-01

Considerable sound levels are produced in primary schools by voices of children and resonance effects. As a consequence, hearing loss and mental impairment may occur. In a Cologne primary school, sound levels were measured in three different classrooms, each with 24 children, 8-10 years old, and one teacher. Sound dosimeters were positioned in the room and near the teacher's ear. Additional measurements were done in one classroom fully equipped with sound-absorbing materials. A questionnaire containing 12 questions about noise at school was distributed to 100 children, 8-10 years old. Measurements were repeated after children had been taught about noise damage and while "noise lights" were used. Mean sound levels of 5-h per day measuring period were 78 dB (A) near the teacher's ear and 70 dB (A) in the room. The average of all measured maximal sound levels for 1 s was 105 dB (A) for teachers, and 100 dB (A) for rooms. In the soundproofed classroom, Leq was 66 dB (A). The questionnaire revealed certain judgment of the children concerning situations with high sound levels and their ability to develop ideas for noise reduction. However, no clear sound level reduction was identified after noise education and using "noise lights" during lessons. Children and their teachers are equally exposed to high sound levels at school. Early sensitization to noise and the possible installation of sound-absorbing materials can be important means to prevent noise-associated hearing loss and mental impairment.

Characterization of Al-ALLOYS (50xx) by Using Positron Annihilation, X-Ray Diffraction and Vibrating Reed Techniques

NASA Astrophysics Data System (ADS)

Kumar, Uday; Badawi, Emad; Mukhopadhyay, P. K.

A series of Al-Mgx alloys, with x = 0.82, 2.09, 2.28, 2.49 and 4.47 wt.%, respectively were characterized by using positron annihilation lifetime studies (PAL), X-ray diffraction (XRD), and sound velocity and internal friction using a vibrating reed technique (VRT). PAL lifetime values increase linearly as the composition is varied, but texturing or preferential orientation is maximum at an intermediate value of composition (x = 2.49%). The internal friction shows a minimum at the same composition, and the sound velocity changes show the maximum value here too. This means that at this composition the sample is the most ordered and defect free.

Sheep as a large animal ear model: Middle-ear ossicular velocities and intracochlear sound pressure.

PubMed

Péus, Dominik; Dobrev, Ivo; Prochazka, Lukas; Thoele, Konrad; Dalbert, Adrian; Boss, Andreas; Newcomb, Nicolas; Probst, Rudolf; Röösli, Christof; Sim, Jae Hoon; Huber, Alexander; Pfiffner, Flurin

2017-08-01

Animals are frequently used for the development and testing of new hearing devices. Dimensions of the middle ear and cochlea differ significantly between humans and commonly used animals, such as rodents or cats. The sheep cochlea is anatomically more like the human cochlea in size and number of turns. This study investigated the middle-ear ossicular velocities and intracochlear sound pressure (ICSP) in sheep temporal bones, with the aim of characterizing the sheep as an experimental model for implantable hearing devices. Measurements were made on fresh sheep temporal bones. Velocity responses of the middle ear ossicles at the umbo, long process of the incus and stapes footplate were measured in the frequency range of 0.25-8 kHz using a laser Doppler vibrometer system. Results were normalized by the corresponding sound pressure level in the external ear canal (P EC ). Sequentially, ICSPs at the scala vestibuli and tympani were then recorded with custom MEMS-based hydrophones, while presenting identical acoustic stimuli. The sheep middle ear transmitted most effectively around 4.8 kHz, with a maximum stapes velocity of 0.2 mm/s/Pa. At the same frequency, the ICSP measurements in the scala vestibuli and tympani showed the maximum gain relative to the P EC (24 dB and 5 dB, respectively). The greatest pressure difference across the cochlear partition occurred between 4 and 6 kHz. A comparison between the results of this study and human reference data showed middle-ear resonance and best cochlear sensitivity at higher frequencies in sheep. In summary, sheep can be an appropriate large animal model for research and development of implantable hearing devices. Copyright © 2017 Elsevier B.V. All rights reserved.

Prediction of light aircraft interior sound pressure level from the measured sound power flowing in to the cabin

NASA Technical Reports Server (NTRS)

Atwal, Mahabir S.; Heitman, Karen E.; Crocker, Malcolm J.

1986-01-01

The validity of the room equation of Crocker and Price (1982) for predicting the cabin interior sound pressure level was experimentally tested using a specially constructed setup for simultaneous measurements of transmitted sound intensity and interior sound pressure levels. Using measured values of the reverberation time and transmitted intensities, the equation was used to predict the space-averaged interior sound pressure level for three different fuselage conditions. The general agreement between the room equation and experimental test data is considered good enough for this equation to be used for preliminary design studies.

Evaluation of the impact of noise metrics on tiltrotor aircraft design

NASA Technical Reports Server (NTRS)

Sternfeld, H.; Spencer, R.; Ziegenbein, P.

1995-01-01

A subjective noise evaluation was conducted in which the test participants evaluated the annoyance of simulated sounds representative of future civil tiltrotor aircraft. The subjective responses were correlated with the noise metrics of A-weighted sound pressure level, overall sound pressure level, and perceived level. The results indicated that correlation between subjective response and A-weighted sound pressure level is considerably enhanced by combining it in a multiple regression with overall sound pressure level. As a single metric, perceived level correlated better than A-weighted sound pressure level due to greater emphasis on low frequency noise components. This latter finding was especially true for indoor noise where the mid and high frequency noise components are attenuated by typical building structure. Using the results of the subjective noise evaluation, the impact on tiltrotor aircraft design was also evaluated. While A-weighted sound pressure level can be reduced by reduction in tip speed, an increase in number of rotor blades is required to achieve significant reduction of low frequency noise as measured by overall sound pressure level. Additional research, however, is required to achieve comparable reductions in impulsive noise due to blade-vortex interaction, and also to achieve reduction in broad band noise.

49 CFR 325.37 - Location and operation of sound level measurement system; highway operations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 5 2011-10-01 2011-10-01 false Location and operation of sound level measurement...; Highway Operations § 325.37 Location and operation of sound level measurement system; highway operations. (a) The microphone of a sound level measurement system that conforms to the rules in § 325.23 of this...

49 CFR 325.71 - Scope of the rules in this subpart.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the sound level generated by a motor vehicle, as displayed on a sound level measurement system, during the measurement of the motor vehicle's sound level emissions at a test site which is not a standard site. (b) The purpose of adding or subtracting a correction factor is to equate the sound level reading...

49 CFR 325.71 - Scope of the rules in this subpart.

Code of Federal Regulations, 2011 CFR

2011-10-01

... the sound level generated by a motor vehicle, as displayed on a sound level measurement system, during the measurement of the motor vehicle's sound level emissions at a test site which is not a standard site. (b) The purpose of adding or subtracting a correction factor is to equate the sound level reading...

Noise level in a neonatal intensive care unit in Santa Marta - Colombia.

PubMed

Garrido Galindo, Angélica Patricia; Camargo Caicedo, Yiniva; Velez-Pereira, Andres M

2017-09-30

The environment of neonatal intensive care units is influenced by numerous sources of noise emission, which contribute to raise the noise levels, and may cause hearing impairment and other physiological and psychological changes on the newborn, as well as problems with care staff. To evaluate the level and sources of noise in the neonatal intensive care unit. Sampled for 20 consecutive days every 60 seconds in A-weighting curves and fast mode with a Type I sound level meter. Recorded the average, maximum and minimum, and the 10th, 50th and 90th percentiles. The values are integrated into hours and work shift, and studied by analysis of variance. The sources were characterized in thirds of octaves. The average level was 64.00 ±3.62 dB(A), with maximum of 76.04 ±5.73 dB(A), minimum of 54.84 ±2.61dB(A), and background noise of 57.95 ±2.83 dB(A). We found four sources with levels between 16.8-63.3 dB(A). Statistical analysis showed significant differences between the hours and work shift, with higher values in the early hours of the day. The values presented exceed the standards suggested by several organizations. The sources identified and measured recorded high values in low frequencies.

Percutaneous versus transcutaneous bone conduction implant system: a feasibility study on a cadaver head.

PubMed

Håkansson, Bo; Eeg-Olofsson, Måns; Reinfeldt, Sabine; Stenfelt, Stefan; Granström, Gösta

2008-12-01

Percutaneous bone-anchored hearing aid (BAHA) is an important rehabilitation alternative for patients who have conductive or mixed hearing loss. However, these devices use a percutaneous and bone-anchored implant that has some drawbacks reported. A transcutaneous bone conduction implant system (BCI) is proposed as an alternative to the percutaneous system because it leaves the skin intact. The BCI transmits the signal to a permanently implanted transducer with an induction loop system through the intact skin. The aim of this study was to compare the electroacoustic performance of the BAHA Classic-300 with a full-scale BCI on a cadaver head in a sound field. The BCI comprised the audio processor of the vibrant sound bridge connected to a balanced vibration transducer (balanced electromagnetic separation transducer). Implants with snap abutments were placed in the parietal bone (Classic-300) and 15-mm deep in the temporal bone (BCI). The vibration responses at the ipsilateral and contralateral cochlear promontories were measured with a laser Doppler vibrometer, with the beam aimed through the ear canal. Results show that the BCI produces approximately 5 dB higher maximum output level and has a slightly lower distortion than the Classic-300 at the ipsilateral promontorium at speech frequencies. At the contralateral promontorium, the maximum output level was considerably lower for the BCI than for the Classic-300 except in the 1-2 kHz range, where it was similar. Present results support the proposal that a BCI system can be a realistic alternative to a BAHA.

[Comfort and noise level in infants with helmet interface].

PubMed

Medina, A; Alvarez Fernández, P; Rey Galán, C; Álvarez Mendiola, P; Álvarez Blanco, S; Vivanco Allende, A

2015-10-01

To evaluate comfort and noise intensity using the COMFORT scale in infants who receive respiratory support with a helmet interface. An observational descriptive study was conducted on all infants (1 to 12 months of age) admitted to a PICU from November 1st 2013 to March 31st 2014 and who received non-invasive ventilation with a helmet interface. Tolerance to the interface was assessed by use of the COMFORT scale. The intensity of the noise to which the infants were exposed was measured with a TES1350A HIBOK 412 sound-level meter. Three measurements were made every day. Twenty seven patients with bronchiolitis (median age: 54 days; range: 10 to 256) were included. Median COMFORT score in the first day was 21 points (14 - 28). An increase in patient comfort was found with a gradual decrease in the scores, with a maximum reduction of 22% from the first hours (score of 22) to the fifth day (score of 18). The minimum sound intensity registered was 42dB, and the maximum was 78dB. Background noise intensity was associated with noise intensity in the helmet. No differences were observed in COMFORT score and noise intensity between ventilator devices. Helmet interface was well tolerated by infants. COMFORT score results are an indicator that infants were comfortable or very comfortable. The measured noise intensity was in the safe range permitted by World Health Organization. Copyright © 2014 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

A national project to evaluate and reduce high sound pressure levels from music.

PubMed

Ryberg, Johanna Bengtsson

2009-01-01

The highest recommended sound pressure levels for leisure sounds (music) in Sweden are 100 dB LAeq and 115 dB LAFmax for adults, and 97 dB LAeq and 110 dB LAFmax where children under the age of 13 have access. For arrangements intended for children, levels should be consistently less than 90 dB LAeq. In 2005, a national project was carried out with the aim of improving environments with high sound pressure levels from music, such as concert halls, restaurants, and cinemas. The project covered both live and recorded music. Of Sweden's 290 municipalities, 134 took part in the project, and 93 of these carried out sound measurements. Four hundred and seventy one establishments were investigated, 24% of which exceeded the highest recommended sound pressure levels for leisure sounds in Sweden. Of festival and concert events, 42% exceeded the recommended levels. Those who visit music events/establishments thus run a relatively high risk of exposure to harmful sound levels. Continued supervision in this field is therefore crucial.

Dynamics of unstable sound waves in a non-equilibrium medium at the nonlinear stage

NASA Astrophysics Data System (ADS)

Khrapov, Sergey; Khoperskov, Alexander

2018-03-01

A new dispersion equation is obtained for a non-equilibrium medium with an exponential relaxation model of a vibrationally excited gas. We have researched the dependencies of the pump source and the heat removal on the medium thermodynamic parameters. The boundaries of sound waves stability regions in a non-equilibrium gas have been determined. The nonlinear stage of sound waves instability development in a vibrationally excited gas has been investigated within CSPH-TVD and MUSCL numerical schemes using parallel technologies OpenMP-CUDA. We have obtained a good agreement of numerical simulation results with the linear perturbations dynamics at the initial stage of the sound waves growth caused by instability. At the nonlinear stage, the sound waves amplitude reaches the maximum value that leads to the formation of shock waves system.

Algorithm Development for a Real-Time Military Noise Monitor

DTIC Science & Technology

2006-03-24

Duration ESLM Enhanced Sound Level Meter ERDC-CERL Engineer Research and Development Center/Construction Engineering Research Laboratory FFT...Fast Fourier Transform FTIG Fort Indiantown Gap Kurt Kurtosis LD Larson Davis Leq Equivalent Sound Level L8eq 8-hr Equivalent...Sound Level Lpk Peak Sound Level m Spectral Slope MCBCL Marine Corps Base Camp Lejeune Neg Number of negative samples NI National

49 CFR 325.57 - Location and operation of sound level measurement systems; stationary test.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 5 2012-10-01 2012-10-01 false Location and operation of sound level measurement...; Stationary Test § 325.57 Location and operation of sound level measurement systems; stationary test. (a) The microphone of a sound level measurement system that conforms to the rules in § 325.23 shall be located at a...

49 CFR 325.57 - Location and operation of sound level measurement systems; stationary test.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 5 2013-10-01 2013-10-01 false Location and operation of sound level measurement...; Stationary Test § 325.57 Location and operation of sound level measurement systems; stationary test. (a) The microphone of a sound level measurement system that conforms to the rules in § 325.23 shall be located at a...

49 CFR 325.23 - Type of measurement systems which may be used.

Code of Federal Regulations, 2011 CFR

2011-10-01

... may be used. The sound level measurement system must meet or exceed the requirements of American National Standard Specification for Sound Level Meters (ANSI S1.4-1971), approved April 27, 1971, issued by..., New York, New York, 10018. (a) A Type 1 sound level meter; (b) A Type 2 sound level meter; or (c) A...

49 CFR 325.57 - Location and operation of sound level measurement systems; stationary test.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 5 2011-10-01 2011-10-01 false Location and operation of sound level measurement...; Stationary Test § 325.57 Location and operation of sound level measurement systems; stationary test. (a) The microphone of a sound level measurement system that conforms to the rules in § 325.23 shall be located at a...

Application of a finite-element model to low-frequency sound insulation in dwellings.

PubMed

Maluski, S P; Gibbs, B M

2000-10-01

The sound transmission between adjacent rooms has been modeled using a finite-element method. Predicted sound-level difference gave good agreement with experimental data using a full-scale and a quarter-scale model. Results show that the sound insulation characteristics of a party wall at low frequencies strongly depend on the modal characteristics of the sound field of both rooms and of the partition. The effect of three edge conditions of the separating wall on the sound-level difference at low frequencies was examined: simply supported, clamped, and a combination of clamped and simply supported. It is demonstrated that a clamped partition provides greater sound-level difference at low frequencies than a simply supported. It also is confirmed that the sound-pressure level difference is lower in equal room than in unequal room configurations.

Behavioral responses of a harbor porpoise (Phocoena phocoena) to playbacks of broadband pile driving sounds.

PubMed

Kastelein, Ronald A; van Heerden, Dorianne; Gransier, Robin; Hoek, Lean

2013-12-01

The high under-water sound pressure levels (SPLs) produced during pile driving to build offshore wind turbines may affect harbor porpoises. To estimate the discomfort threshold of pile driving sounds, a porpoise in a quiet pool was exposed to playbacks (46 strikes/min) at five SPLs (6 dB steps: 130-154 dB re 1 μPa). The spectrum of the impulsive sound resembled the spectrum of pile driving sound at tens of kilometers from the pile driving location in shallow water such as that found in the North Sea. The animal's behavior during test and baseline periods was compared. At and above a received broadband SPL of 136 dB re 1 μPa [zero-peak sound pressure level: 151 dB re 1 μPa; t90: 126 ms; sound exposure level of a single strike (SELss): 127 dB re 1 μPa(2) s] the porpoise's respiration rate increased in response to the pile driving sounds. At higher levels, he also jumped out of the water more often. Wild porpoises are expected to move tens of kilometers away from offshore pile driving locations; response distances will vary with context, the sounds' source level, parameters influencing sound propagation, and background noise levels. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparing Average Levels and Peak Occurrence of Overnight Sound in the Medical Intensive Care Unit on A-weighted and C-weighted Decibel Scales

PubMed Central

Knauert, Melissa; Jeon, Sangchoon; Murphy, Terrence E.; Yaggi, H. Klar; Pisani, Margaret A.; Redeker, Nancy S.

2016-01-01

Purpose Sound levels in the intensive care unit (ICU) are universally elevated and are believed to contribute to sleep and circadian disruption. The purpose of this study is to compare overnight ICU sound levels and peak occurrence on A- versus C-weighted scales. Materials and Methods This was a prospective observational study of overnight sound levels in 59 medical ICU patient rooms. Sound level was recorded every 10 seconds on A- and C-weighted decibel scales. Equivalent sound level (Leq) and sound peaks were reported for full and partial night periods. Results The overnight A-weighted Leq of 53.6 dBA was well above World Health Organization (WHO) recommendations; overnight C-weighted Leq was 63.1 dBC (no WHO recommendations). Peak sound occurrence ranged from 1.8 to 23.3 times per hour. Illness severity, mechanical ventilation and delirium were not associated with Leq or peak occurrence. Leq and peak measures for A- and C-weighted decibel scales were significantly different from each other. Conclusions Sound levels in the medical ICU are high throughout the night. Patient factors were not associated with Leq or peak occurrence. Significant discordance between A- and C-weighted values suggests that low frequency sound is a meaningful factor in the medical ICU environment. PMID:27546739

Potential Population Consequences of Active Sonar Disturbance in Atlantic Herring: Estimating the Maximum Risk.

PubMed

Sivle, Lise Doksæter; Kvadsheim, Petter Helgevold; Ainslie, Michael

2016-01-01

Effects of noise on fish populations may be predicted by the population consequence of acoustic disturbance (PCAD) model. We have predicted the potential risk of population disturbance when the highest sound exposure level (SEL) at which adult herring do not respond to naval sonar (SEL(0)) is exceeded. When the population density is low (feeding), the risk is low even at high sonar source levels and long-duration exercises (>24 h). With densely packed populations (overwintering), a sonar exercise might expose the entire population to levels >SEL(0) within a 24-h exercise period. However, the disturbance will be short and the response threshold used here is highly conservative. It is therefore unlikely that naval sonar will significantly impact the herring population.

Noise in neonatal intensive care units (NICUs) and its effect on high risk newborns

NASA Astrophysics Data System (ADS)

Lasky, Robert E.; Williams, Amber L.; van Drongelen, Wim; Gray, Lincoln C.

2005-09-01

We conducted sound surveys in a large state of the art NICU with six separate rooms devoted to the sickest babies requiring the most intensive care (Level III) and six rooms devoted to babies requiring special but less intensive care (Level II). Each room was capable of caring for up to 8 babies. Additionally, there were 8 individual Isolation rooms. We used Larson Davis Spark squflg 703+ dosimeters to record 21 week long sound surveys, seven in each type of room. The American Academy of Pediatrics (1997) has recommended that sound levels in NICUs should never exceed 45 dB(A). That recommendation was exceeded 73.6% of the time in Level II, 92.1% of the time in Isolation, and 96.6% of the time in Level III. Sound levels were lowest in the Level II rooms especially for the softest sounds recorded (L90 and L70). Level III rooms were noisiest except for the noisiest decile of sound (L10). Isolation rooms were noisiest at the highest sound levels (probably because of their reverberant construction materials and enclosed space). Autocorrelation functions were calculated identifying periodic components in all three rooms at about 12 and 24 hrs. Periodic variations were very small compared to random sound variations.

Common sole larvae survive high levels of pile-driving sound in controlled exposure experiments.

PubMed

Bolle, Loes J; de Jong, Christ A F; Bierman, Stijn M; van Beek, Pieter J G; van Keeken, Olvin A; Wessels, Peter W; van Damme, Cindy J G; Winter, Hendrik V; de Haan, Dick; Dekeling, René P A

2012-01-01

In view of the rapid extension of offshore wind farms, there is an urgent need to improve our knowledge on possible adverse effects of underwater sound generated by pile-driving. Mortality and injuries have been observed in fish exposed to loud impulse sounds, but knowledge on the sound levels at which (sub-)lethal effects occur is limited for juvenile and adult fish, and virtually non-existent for fish eggs and larvae. A device was developed in which fish larvae can be exposed to underwater sound. It consists of a rigid-walled cylindrical chamber driven by an electro-dynamical sound projector. Samples of up to 100 larvae can be exposed simultaneously to a homogeneously distributed sound pressure and particle velocity field. Recorded pile-driving sounds could be reproduced accurately in the frequency range between 50 and 1000 Hz, at zero to peak pressure levels up to 210 dB re 1µPa(2) (zero to peak pressures up to 32 kPa) and single pulse sound exposure levels up to 186 dB re 1µPa(2)s. The device was used to examine lethal effects of sound exposure in common sole (Solea solea) larvae. Different developmental stages were exposed to various levels and durations of pile-driving sound. The highest cumulative sound exposure level applied was 206 dB re 1µPa(2)s, which corresponds to 100 strikes at a distance of 100 m from a typical North Sea pile-driving site. The results showed no statistically significant differences in mortality between exposure and control groups at sound exposure levels which were well above the US interim criteria for non-auditory tissue damage in fish. Although our findings cannot be extrapolated to fish larvae in general, as interspecific differences in vulnerability to sound exposure may occur, they do indicate that previous assumptions and criteria may need to be revised.

Common Sole Larvae Survive High Levels of Pile-Driving Sound in Controlled Exposure Experiments

PubMed Central

Bolle, Loes J.; de Jong, Christ A. F.; Bierman, Stijn M.; van Beek, Pieter J. G.; van Keeken, Olvin A.; Wessels, Peter W.; van Damme, Cindy J. G.; Winter, Hendrik V.; de Haan, Dick; Dekeling, René P. A.

2012-01-01

In view of the rapid extension of offshore wind farms, there is an urgent need to improve our knowledge on possible adverse effects of underwater sound generated by pile-driving. Mortality and injuries have been observed in fish exposed to loud impulse sounds, but knowledge on the sound levels at which (sub-)lethal effects occur is limited for juvenile and adult fish, and virtually non-existent for fish eggs and larvae. A device was developed in which fish larvae can be exposed to underwater sound. It consists of a rigid-walled cylindrical chamber driven by an electro-dynamical sound projector. Samples of up to 100 larvae can be exposed simultaneously to a homogeneously distributed sound pressure and particle velocity field. Recorded pile-driving sounds could be reproduced accurately in the frequency range between 50 and 1000 Hz, at zero to peak pressure levels up to 210 dB re 1µPa2 (zero to peak pressures up to 32 kPa) and single pulse sound exposure levels up to 186 dB re 1µPa2s. The device was used to examine lethal effects of sound exposure in common sole (Solea solea) larvae. Different developmental stages were exposed to various levels and durations of pile-driving sound. The highest cumulative sound exposure level applied was 206 dB re 1µPa2s, which corresponds to 100 strikes at a distance of 100 m from a typical North Sea pile-driving site. The results showed no statistically significant differences in mortality between exposure and control groups at sound exposure levels which were well above the US interim criteria for non-auditory tissue damage in fish. Although our findings cannot be extrapolated to fish larvae in general, as interspecific differences in vulnerability to sound exposure may occur, they do indicate that previous assumptions and criteria may need to be revised. PMID:22431996

Effect of the spectrum of a high-intensity sound source on the sound-absorbing properties of a resonance-type acoustic lining

NASA Astrophysics Data System (ADS)

Ipatov, M. S.; Ostroumov, M. N.; Sobolev, A. F.

2012-07-01

Experimental results are presented on the effect of both the sound pressure level and the type of spectrum of a sound source on the impedance of an acoustic lining. The spectra under study include those of white noise, a narrow-band signal, and a signal with a preset waveform. It is found that, to obtain reliable data on the impedance of an acoustic lining from the results of interferometric measurements, the total sound pressure level of white noise or the maximal sound pressure level of a pure tone (at every oscillation frequency) needs to be identical to the total sound pressure level of the actual source at the site of acoustic lining on the channel wall.

24 CFR 51.103 - Criteria and standards.

Code of Federal Regulations, 2010 CFR

2010-04-01

... decibels to sound levels in the night from 10 p.m. to 7 a.m. Mathematical expressions for average sound..., as indicated in § 51.106(a)(3). Methods for assessing the contribution of loud impulsive sounds to day-night average sound level at a site and mathematical expressions for determining whether a sound...

A New Resonance Tube

NASA Astrophysics Data System (ADS)

Bates, Alan

2017-12-01

The measurement of the speed of sound in air with the resonance tube is a popular experiment that often yields accurate results. One approach is to hold a vibrating tuning fork over an air column that is partially immersed in water. The column is raised and lowered in the water until the generated standing wave produces resonance: this occurs at the point where sound is perceived to have maximum loudness, or at the point where the amplitude of the standing wave has maximum value, namely an antinode. An antinode coincides with the position of the tuning fork, beyond the end of the air column, which consequently introduces an end correction. One way to minimize this end correction is to measure the distance between consecutive antinodes.

Encoding of sound envelope transients in the auditory cortex of juvenile rats and adult rats.

PubMed

Lu, Qi; Jiang, Cuiping; Zhang, Jiping

2016-02-01

Accurate neural processing of time-varying sound amplitude and spectral information is vital for species-specific communication. During postnatal development, cortical processing of sound frequency undergoes progressive refinement; however, it is not clear whether cortical processing of sound envelope transients also undergoes age-related changes. We determined the dependence of neural response strength and first-spike latency on sound rise-fall time across sound levels in the primary auditory cortex (A1) of juvenile (P20-P30) rats and adult (8-10 weeks) rats. A1 neurons were categorized as "all-pass", "short-pass", or "mixed" ("all-pass" at high sound levels to "short-pass" at lower sound levels) based on the normalized response strength vs. rise-fall time functions across sound levels. The proportions of A1 neurons within each of the three categories in juvenile rats were similar to that in adult rats. In general, with increasing rise-fall time, the average response strength decreased and the average first-spike latency increased in A1 neurons of both groups. At a given sound level and rise-fall time, the average normalized neural response strength did not differ significantly between the two age groups. However, the A1 neurons in juvenile rats showed greater absolute response strength, longer first-spike latency compared to those in adult rats. In addition, at a constant sound level, the average first-spike latency of juvenile A1 neurons was more sensitive to changes in rise-fall time. Our results demonstrate the dependence of the responses of rat A1 neurons on sound rise-fall time, and suggest that the response latency exhibit some age-related changes in cortical representation of sound envelope rise time. Copyright © 2015 Elsevier Ltd. All rights reserved.

The influence of neonatal intensive care unit design on sound level.

PubMed

Chen, Hsin-Li; Chen, Chao-Huei; Wu, Chih-Chao; Huang, Hsiu-Jung; Wang, Teh-Ming; Hsu, Chia-Chi

2009-12-01

Excessive noise in nurseries has been found to cause adverse effects in infants, especially preterm infants in neonatal intensive care units (NICUs). The NICU design may influence the background sound level. We compared the sound level in two differently designed spaces in one NICU. We hypothesized that the sound level in an enclosed space would be quieter than in an open space. Sound levels were measured continuously 24 hours a day in two separate spaces at the same time, one enclosed and one open. Sound-level meters were placed near beds in each room. Sound levels were expressed as decibels, A-weighted (dBA) and presented as hourly L(eq), L(max), L(10), and L(90). The hourly L(eq) in the open space (50.8-57.2dB) was greater than that of the enclosed space (45.9-51.7dB), with a difference of 0.4-10.4dB, and a mean difference of 4.5dB (p<0.0001). The hourly L(10), L(90), and L(max) in the open space also exceeded that in the enclosed space (p<0.0001). The sound level measured in the enclosed space was quieter than in the open space. The design of bed space should be taken into consideration when building a new NICU. Besides the design of NICU architecture, continuous monitoring of sound level in the NICU is important to maintain a quiet environment.

The influence of flooring on environmental stressors: a study of three flooring materials in a hospital.

PubMed

Harris, Debra D

2015-01-01

Three flooring materials, terrazzo, rubber, and carpet tile, in patient unit corridors were compared for absorption of sound, comfort, light reflectance, employee perceptions and preferences, and patient satisfaction. Environmental stressors, such as noise and ergonomic factors, effect healthcare workers and patients, contributing to increased fatigue, anxiety and stress, decreased productivity, and patient safety and satisfaction. A longitudinal comparative cohort study comparing three types of flooring assessed sound levels, healthcare worker responses, and patient Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) ratings over 42 weeks. A linear mixed model analysis was conducted to determine significant differences between the means for participant responses and objective sound meter data during all three phases of the study. A significant difference was found for sound levels between flooring type for equivalent continuous sound levels. Carpet tile performed better for sound attenuation by absorption, reducing sound levels 3.14 dBA. Preferences for flooring materials changed over the course of the study. The HCAHPS ratings aligned with the sound meter data showing that patients perceived the noise levels to be lower with carpet tiles, improving patient satisfaction ratings. Perceptions for healthcare staff and patients were aligned with the sound meter data. Carpet tile provides sound absorption that affects sound levels and influences occupant's perceptions of environmental factors that contribute to the quality of the indoor environment. Flooring that provides comfort underfoot, easy cleanability, and sound absorption influence healthcare worker job satisfaction and patient satisfaction with their patient experience. © The Author(s) 2015.

Postnatal development of echolocation abilities in a bottlenose dolphin (Tursiops truncatus): temporal organization.

PubMed

Favaro, Livio; Gnone, Guido; Pessani, Daniela

2013-03-01

In spite of all the information available on adult bottlenose dolphin (Tursiops truncatus) biosonar, the ontogeny of its echolocation abilities has been investigated very little. Earlier studies have reported that neonatal dolphins can produce both whistles and burst-pulsed sounds just after birth and that early-pulsed sounds are probably a precursor of echolocation click trains. The aim of this research is to investigate the development of echolocation signals in a captive calf, born in the facilities of the Acquario di Genova. A set of 81 impulsive sounds were collected from birth to the seventh postnatal week and six additional echolocation click trains were recorded when the dolphin was 1 year old. Moreover, behavioral observations, concurring with sound production, were carried out by means of a video camera. For each sound we measured five acoustic parameters: click train duration (CTD), number of clicks per train, minimum, maximum, and mean click repetition rate (CRR). CTD and number of clicks per train were found to increase with age. Maximum and mean CRR followed a decreasing trend with dolphin growth starting from the second postnatal week. The calf's first head scanning movement was recorded 21 days after birth. Our data suggest that in the bottlenose dolphin the early postnatal weeks are essential for the development of echolocation abilities and that the temporal features of the echolocation click trains remain relatively stable from the seventh postnatal week up to the first year of life. © 2013 Wiley Periodicals, Inc.

Enhancing maximum measurable sound reduction index using sound intensity method and strong receiving room absorption.

PubMed

Hongisto, V; Lindgren, M; Keränen, J

2001-01-01

The sound intensity method is usually recommended instead of the pressure method in the presence of strong flanking transmission. Especially when small and/or heavy specimens are tested, the flanking often causes problems in laboratories practicing only the pressure method. The purpose of this study was to determine experimentally the difference between the maximum sound reduction indices obtained by the intensity method, RI,max, and by the pressure method, Rmax. In addition, the influence of adding room absorption to the receiving room was studied. The experiments were carried out in an ordinary two-room test laboratory. The exact value of RI,max was estimated by applying a fitting equation to the measured data points. The fitting equation involved the dependence of the pressure-intensity indicator on measured acoustical parameters. In an empty receiving room, the difference between RI,max and Rmax was 4-15 dB, depending on frequency. When the average reverberation time was reduced from 3.5 to 0.6 s, the values of RI,max increased by 2-10 dB compared to the results in the empty room. Thus, it is possible to measure wall structures having 9-22 dB better sound reduction index using the intensity method than with the pressure method. This facilitates the measurements of small and/or heavy specimens in the presence of flanking. Moreover, when new laboratories are designed, the intensity method is an alternative to the pressure method which presupposes expensive isolation structures between the rooms.

Effects of sound level fluctuations on annoyance caused by aircraft-flyover noise

NASA Technical Reports Server (NTRS)

Mccurdy, D. A.

1979-01-01

A laboratory experiment was conducted to determine the effects of variations in the rate and magnitude of sound level fluctuations on the annoyance caused by aircraft-flyover noise. The effects of tonal content, noise duration, and sound pressure level on annoyance were also studied. An aircraft-noise synthesis system was used to synthesize 32 aircraft-flyover noise stimuli representing the factorial combinations of 2 tone conditions, 2 noise durations, 2 sound pressure levels, 2 level fluctuation rates, and 2 level fluctuation magnitudes. Thirty-two test subjects made annoyance judgements on a total of 64 stimuli in a subjective listening test facility simulating an outdoor acoustic environment. Variations in the rate and magnitude of level fluctuations were found to have little, if any, effect on annoyance. Tonal content, noise duration, sound pressure level, and the interaction of tonal content with sound pressure level were found to affect the judged annoyance significantly. The addition of tone corrections and/or duration corrections significantly improved the annoyance prediction ability of noise rating scales.

Decoding sound level in the marmoset primary auditory cortex.

PubMed

Sun, Wensheng; Marongelli, Ellisha N; Watkins, Paul V; Barbour, Dennis L

2017-10-01

Neurons that respond favorably to a particular sound level have been observed throughout the central auditory system, becoming steadily more common at higher processing areas. One theory about the role of these level-tuned or nonmonotonic neurons is the level-invariant encoding of sounds. To investigate this theory, we simulated various subpopulations of neurons by drawing from real primary auditory cortex (A1) neuron responses and surveyed their performance in forming different sound level representations. Pure nonmonotonic subpopulations did not provide the best level-invariant decoding; instead, mixtures of monotonic and nonmonotonic neurons provided the most accurate decoding. For level-fidelity decoding, the inclusion of nonmonotonic neurons slightly improved or did not change decoding accuracy until they constituted a high proportion. These results indicate that nonmonotonic neurons fill an encoding role complementary to, rather than alternate to, monotonic neurons. NEW & NOTEWORTHY Neurons with nonmonotonic rate-level functions are unique to the central auditory system. These level-tuned neurons have been proposed to account for invariant sound perception across sound levels. Through systematic simulations based on real neuron responses, this study shows that neuron populations perform sound encoding optimally when containing both monotonic and nonmonotonic neurons. The results indicate that instead of working independently, nonmonotonic neurons complement the function of monotonic neurons in different sound-encoding contexts. Copyright © 2017 the American Physiological Society.

Comparison of the produced and perceived voice range profiles in untrained and trained classical singers.

PubMed

Hunter, Eric J; Svec, Jan G; Titze, Ingo R

2006-12-01

Frequency and intensity ranges (in true decibel sound pressure level, 20 microPa at 1 m) of voice production in trained and untrained vocalists were compared with the perceived dynamic range (phons) and units of loudness (sones) of the ear. Results were reported in terms of standard voice range profiles (VRPs), perceived VRPs (as predicted by accepted measures of auditory sensitivities), and a new metric labeled as an overall perceptual level construct. Trained classical singers made use of the most sensitive part of the hearing range (around 3-4 kHz) through the use of the singer's formant. When mapped onto the contours of equal loudness (depicting nonuniform spectral and dynamic sensitivities of the auditory system), the formant is perceived at an even higher sound level, as measured in phons, than a flat or A-weighted spectrum would indicate. The contributions of effects like the singer's formant and the sensitivities of the auditory system helped the trained singers produce 20% to 40% more units of loudness, as measured in sones, than the untrained singers. Trained male vocalists had a maximum overall perceptual level construct that was 40% higher than the untrained male vocalists. Although the A-weighted spectrum (commonly used in VRP measurement) is a reasonable first-order approximation of auditory sensitivities, it misrepresents the most salient part of the sensitivities (where the singer's formant is found) by nearly 10 dB.

33 CFR 86.07 - Directional properties.

Code of Federal Regulations, 2011 CFR

2011-07-01

... properties. The sound pressure level of a directional whistle shall be not more than 4 dB below the sound... forward axis. The sound pressure level of the whistle in any other direction in the horizontal plane shall not be more than 10 dB less than the sound pressure level specified for the forward axis, so that the...

Concerns of the Institute of Transport Study and Research for reducing the sound level inside completely repaired buses. [noise and vibration control

NASA Technical Reports Server (NTRS)

Groza, A.; Calciu, J.; Nicola, I.; Ionasek, A.

1974-01-01

Sound level measurements on noise sources on buses are used to observe the effects of attenuating acoustic pressure levels inside the bus by sound-proofing during complete repair. A spectral analysis of the sound level as a function of motor speed, bus speed along the road, and the category of the road is reported.

The sound intensity and characteristics of variable-pitch pulse oximeters.

PubMed

Yamanaka, Hiroo; Haruna, Junichi; Mashimo, Takashi; Akita, Takeshi; Kinouchi, Keiko

2008-06-01

Various studies worldwide have found that sound levels in hospitals significantly exceed the World Health Organization (WHO) guidelines, and that this noise is associated with audible signals from various medical devices. The pulse oximeter is now widely used in health care; however the health effects associated with the noise from this equipment remain largely unclarified. Here, we analyzed the sounds of variable-pitch pulse oximeters, and discussed the possible associated risk of sleep disturbance, annoyance, and hearing loss. The Nellcor N 595 and Masimo SET Radical pulse oximeters were measured for equivalent continuous A-weighted sound pressure levels (L(Aeq)), loudness levels, and loudness. Pulse beep pitches were also identified using Fast Fourier Transform (FFT) analysis and compared with musical pitches as controls. Almost all alarm sounds and pulse beeps from the instruments tested exceeded 30 dBA, a level that may induce sleep disturbance and annoyance. Several alarm sounds emitted by the pulse oximeters exceeded 70 dBA, which is known to induce hearing loss. The loudness of the alarm sound of each pulse oximeter did not change in proportion to the sound volume level. The pitch of each pulse beep did not correspond to musical pitch levels. The results indicate that sounds from pulse oximeters pose a potential risk of not only sleep disturbance and annoyance but also hearing loss, and that these sounds are unnatural for human auditory perception.

Measurement of respiratory acoustical signals. Comparison of sensors.

PubMed

Pasterkamp, H; Kraman, S S; DeFrain, P D; Wodicka, G R

1993-11-01

We assessed the performance of three air-coupled and four contact sensors under standardized conditions of lung sound recording. Recordings were obtained from three of the investigators at the best site on the posterior lower chest as determined by auscultation. Lung sounds were band-pass filtered between 100 and 2,000 Hz and sampled simultaneously with calibrated airflow at a rate of 10 kHz. Fourier techniques were used for power spectral analysis. Average spectra for inspiratory sounds at flows of 2 +/- 0.5 L/s were referenced against background noise at zero flow. Air-coupled and contact sensors had comparable maximum signal-to-noise ratios and gave similar values for most spectral parameters. Unexpectedly, less sensitivity (lower signal-to-noise ratio) at high frequencies was observed in the air-coupled devices. Sensor performance needs to be characterized in studies of lung sounds. We suggest that lung sound spectra should be averaged at known airflows over several breaths and that all measurements should be reported relative to sounds recorded at zero flow.

The effect of spatial distribution on the annoyance caused by simultaneous sounds

NASA Astrophysics Data System (ADS)

Vos, Joos; Bronkhorst, Adelbert W.; Fedtke, Thomas

2004-05-01

A considerable part of the population is exposed to simultaneous and/or successive environmental sounds from different sources. In many cases, these sources are different with respect to their locations also. In a laboratory study, it was investigated whether the annoyance caused by the multiple sounds is affected by the spatial distribution of the sources. There were four independent variables: (1) sound category (stationary or moving), (2) sound type (stationary: lawn-mower, leaf-blower, and chain saw; moving: road traffic, railway, and motorbike), (3) spatial location (left, right, and combinations), and (4) A-weighted sound exposure level (ASEL of single sources equal to 50, 60, or 70 dB). In addition to the individual sounds in isolation, various combinations of two or three different sources within each sound category and sound level were presented for rating. The annoyance was mainly determined by sound level and sound source type. In most cases there were neither significant main effects of spatial distribution nor significant interaction effects between spatial distribution and the other variables. It was concluded that for rating the spatially distrib- uted sounds investigated, the noise dose can simply be determined by a summation of the levels for the left and right channels. [Work supported by CEU.

Psychophysiological acoustics of indoor sound due to traffic noise during sleep

NASA Astrophysics Data System (ADS)

Tulen, J. H. M.; Kumar, A.; Jurriëns, A. A.

1986-10-01

The relation between the physical characteristics of sound and an individual's perception of its as annoyance is complex and unclear. Sleep disturbance by sound is manifested in the physiological responses to the sound stimuli and the quality of sleep perceived in the morning. Both may result in deterioration of functioning during wakefulness. Therefore, psychophysiological responses to noise during sleep should be studied for the evaluation of the efficacy of sound insulation. Nocturnal sleep and indoor sound level were recorded in the homes of 12 subjects living along a highway with high traffic density. Double glazing sound insulation was used to create two experimental conditions: low insulation and high insulation. Twenty recordings were made per subject, ten recordings in each condition. During the nights with low insulation the quality of sleep was so low that both performance and mood were negatively affected. The enhancement of sound insulation was not effective enough to increase the restorative effects of sleep. The transient and peaky characteristics of traffic sound were also found to result in non-adaptive physiological responses during sleep. Sound insulation did have an effect on noise peak characteristics such as peak level, peak duration and slope. However, the number of sound peaks were found to be the same in both conditions. The relation of these sound peaks detected in the indoor recorded sound level signal to characteristics of passing vehicles was established, indicating that the sound peaks causing the psychophysiological disturbances during sleep were generated by the passing vehicles. Evidence is presented to show that the reduction in sound level is not a good measure of efficacy of sound insulation. The parameters of the sound peaks, as described in this paper, are a better representation of psychophysiological efficacy of sound insulation.

High sound pressure levels in Bavarian discotheques remain after introduction of voluntary agreements.

PubMed

Twardella, Dorothee; Wellhoefer, Andrea; Brix, Jutta; Fromme, Hermann

2008-01-01

While no legal rules or regulations exist in Germany, voluntary measures were introduced to achieve a reduction of sound pressure levels in discotheques to levels below 100 dB(A). To evaluate the current levels in Bavarian discotheques and to find out whether these voluntary measures ensured compliance with the recommended limits, sound pressure levels were measured in 20 Bavarian discotheques between 11 p.m. and 2 a.m. With respect to the equivalent continuous A-weighted sound pressure level for each 30-minute period (L Aeq,30min ), only 4/20 discotheques remained below the limit of 100 dB(A) in all time periods. Ten discotheques had sound pressure levels below 100 dB(A) for the total measurement period (L Aeq,180min ). None of the evaluated factors (weekday, size, estimated age of attendees, the use of voluntary measures such as participation of disc jockeys in a tutorial, or the availability of a sound level meter for the DJs) was significantly associated with the maximal L Aeq, 30min . Thus, the introduction of voluntary measures was not sufficient to ensure compliance with the recommended limits of sound pressure levels.

Topography of sound level representation in the FM sweep selective region of the pallid bat auditory cortex.

PubMed

Measor, Kevin; Yarrow, Stuart; Razak, Khaleel A

2018-05-26

Sound level processing is a fundamental function of the auditory system. To determine how the cortex represents sound level, it is important to quantify how changes in level alter the spatiotemporal structure of cortical ensemble activity. This is particularly true for echolocating bats that have control over, and often rapidly adjust, call level to actively change echo level. To understand how cortical activity may change with sound level, here we mapped response rate and latency changes with sound level in the auditory cortex of the pallid bat. The pallid bat uses a 60-30 kHz downward frequency modulated (FM) sweep for echolocation. Neurons tuned to frequencies between 30 and 70 kHz in the auditory cortex are selective for the properties of FM sweeps used in echolocation forming the FM sweep selective region (FMSR). The FMSR is strongly selective for sound level between 30 and 50 dB SPL. Here we mapped the topography of level selectivity in the FMSR using downward FM sweeps and show that neurons with more monotonic rate level functions are located in caudomedial regions of the FMSR overlapping with high frequency (50-60 kHz) neurons. Non-monotonic neurons dominate the FMSR, and are distributed across the entire region, but there is no evidence for amplitopy. We also examined how first spike latency of FMSR neurons change with sound level. The majority of FMSR neurons exhibit paradoxical latency shift wherein the latency increases with sound level. Moreover, neurons with paradoxical latency shifts are more strongly level selective and are tuned to lower sound level than neurons in which latencies decrease with level. These data indicate a clustered arrangement of neurons according to monotonicity, with no strong evidence for finer scale topography, in the FMSR. The latency analysis suggests mechanisms for strong level selectivity that is based on relative timing of excitatory and inhibitory inputs. Taken together, these data suggest how the spatiotemporal spread of cortical activity may represent sound level. Copyright © 2018. Published by Elsevier B.V.

A Lagrangian analysis of mid-latitude stratospheric ozone variability and long-term trends.

NASA Astrophysics Data System (ADS)

Koch, G.; Wernli, H.; Staehelin, J.; Peter, T.

2002-05-01

A systematic Lagrangian investigation is performed of wintertime high-resolution stratospheric ozone soundings at Payerne, Switzerland, from January 1970 to March 2001. For every ozone sounding, 10-day backward trajectories have been calculated on 16 isentropic levels using NCEP reanalysis data. Both the minimum/maximum latitude and potential vorticity (PV) averaged along the trajectories are used as indicators of the air parcels' ``origin''. The importance of transport for the understandin g of single ozone profiles is confirmed by a statistical analysis which shows that negative/positive ozone deviations gener ally coincide with transport from regions with climatologically low/high ozone values. The stable relationship between PV and ozone for the 32 year period indicates either no direct chemical impact or no temporal change of this impact. In the upper layer the PV-ozone relationship changes significantly after 1987 and a separate trend analysis for air masses transported from the polar, midlatitude and subtropical regions shows negative ozone trends in all three categories (with a maximum for the polar region). This is not direct evidence for, but would be in agreement with, an increased chemical ozone depletion in the Arctic since the late 1980s. The reasons for the negative trend in the mid-stratospheric air masses with subtropical origin that are in qualitative agreement with recent satellite observations are presently unknown.

Investigation of coaxial jet noise and inlet choking using an F-111A airplane

NASA Technical Reports Server (NTRS)

Putnam, T. W.

1973-01-01

Measurements of engine noise generated by an F-111A airplane positioned on a thrustmeasuring platform were made at angles of 0 deg to 160 deg from the aircraft heading. Sound power levels, power spectra, and directivity patterns are presented for jet exit velocities between 260 feet per second and 2400 feet per second. The test results indicate that the total acoustic power was proportional to the eighth power of the core jet velocity for core exhaust velocities greater than 300 meters per second (985 feet per second) and that little or no mixing of the core and fan streams occurred. The maximum sideline noise was most accurately predicted by using the average jet velocity for velocities above 300 meters per second (985 feet per second). The acoustic power spectrum was essentially the same for the single jet flow of afterburner operation and the coaxial flow of the nonafterburning condition. By varying the inlet geometry and cowl position, reductions in the sound pressure level of the blade passing frequency on the order of 15 decibels to 25 decibels were observed for inlet Mach numbers of 0.8 to 0.9.

Comparison of SAGE II ozone measurements and ozone soundings at Uccle (Belgium) during the period February 1985 to January 1986

NASA Technical Reports Server (NTRS)

De Muer, D.; De Backer, H.; Zawodny, J. M.; Veiga, R. E.

1990-01-01

The ozone profiles obtained from 24 balloon soundings at Uccle (50 deg 48 min N, 4 deg 21 min E) made with electrochemical ozonesondes were used as correlative data for SAGE II ozone profiles retrieved within a distance of at most 600 km from Uccle. The agreement between the two data sets is in general quite good, especially for profiles nearly coincident in time and space, and during periods of little dynamic activity over the area considered. The percent difference between the ozone column density of the mean balloon and SAGE profile is 4.4 percent (-3.3) percent in the altitude region between 10 and 26 km. From a statistical analysis it appears that there is a small but meaningful difference between the mean profiles at the level of the ozone maximum and around the 30-km level. An error analysis of both data sets give similar results, leading to the conclusion that these differences are instrumentally induced. However, differences between the mean profiles in the lower stratosphere are probably real and due to the high ozone variability in time and space in that altitude region.

Transient Electromagnetic Soundings Near Great Sand Dunes National Park and Preserve, San Luis Valley, Colorado (2006 Field Season)

USGS Publications Warehouse

Fitterman, David V.; de Sozua Filho, Oderson A.

2009-01-01

Time-domain electromagnetic (TEM) soundings were made near Great Sand Dunes National Park and Preserve in the San Luis Valley of southern Colorado to obtain subsurface information of use to hydrologic modeling. Seventeen soundings were made to the east and north of the sand dunes. Using a small loop TEM system, maximum exploration depths of about 75 to 150 m were obtained. In general, layered earth interpretations of the data found that resistivity decreases with depth. Comparison of soundings with geologic logs from nearby wells found that zones logged as having increased clay content usually corresponded with a significant resistivity decrease in the TEM determined model. This result supports the use of TEM soundings to map the location of the top of the clay unit deposited at the bottom of the ancient Lake Alamosa that filled the San Luis Valley from Pliocene to middle Pleistocene time.

The masking of beluga whale (Delphinapterus leucas) vocalizations by icebreaker noise

NASA Astrophysics Data System (ADS)

Erbe, Christine

1998-11-01

This thesis examines the masking effect of underwater noise on beluga whale communication. As ocean water is greatly opaque for light but well conducting for sound, marine mammals rely primarily on their hearing for orientation and communication. Man-made underwater noise has the potential of interfering with sounds used by marine mammals. Masking to the point of incomprehensibility can have fatal results-for the individual, but ultimately for the entire species. As part of our understanding of whether marine mammals can cope with human impact on nature, this thesis is the first to study the interference of real ocean noises with complex animal vocalizations. At the Vancouver Aquarium, a beluga whale was trained for acoustic experiments, during which masked hearing thresholds were measured. Focus lay on noise created by icebreaking ships in the Arctic. As experiments with trained animals are time and cost expensive, various techniques were examined for their ability to model the whale's response. These were human hearing tests, visual spectrogram discrimination, matched filtering, spectrogram cross-correlation, critical band cross-correlation, adaptive filtering and various types of artificial neural networks. The most efficient method with respect to similarity to the whale's data and speed, was a backpropagation neural net. Masked hearing thresholds would be of little use if they could not be related to accessible quantities in the wild. An ocean sound propagation model was applied to determine critical distances between a noise source, a calling whale and a listening whale. Colour diagrams, called maskograms, were invented to illustrate zones of masking in the wild. Results are that bubbler system noise with a source level of 194 dB re 1 μPa at 1 m has a maximum radius of masking of 15 km in a 3- dimensional ocean. Propeller noise with a source level of 203 dB re 1 μPa at 1 m has a maximum radius of masking of 22 km. A naturally occurring icecracking event with a source level of 147 dB re 1 μPa at 1 m only masks if the listening whale is within 8 m of the event. Therefore, in the wild, propeller cavitation noise masks furthest, followed by bubbler system noise, then icecracking noise.

Integrating terrestrial and marine records of the LGM in McMurdo Sound, Antarctica: implications for grounded ice expansion, ice flow, and deglaciation of the Ross Sea Embayment

NASA Astrophysics Data System (ADS)

Christ, A. J.; Marchant, D. R.

2017-12-01

During the LGM, grounded glacier ice filled the Ross Embayment and deposited glacial drift on volcanic islands and peninsulas in McMurdo Sound, as well as along coastal regions of the Transantarctic Mountains (TAM), including the McMurdo Dry Valleys and Royal Society Range. The flow geometry and retreat history of this ice remains debated, with contrasting views yielding divergent implications for both the fundamental cause of Antarctic ice expansion as well as the interaction and behavior of ice derived from East and West Antarctica during late Quaternary time. We present terrestrial geomorphologic evidence that enables the reconstruction of former ice elevations, ice-flow paths, and ice-marginal environments in McMurdo Sound. Radiocarbon dates of fossil algae interbedded with ice-marginal sediments provide a coherent timeline for local ice retreat. These data are integrated with marine-sediment records and multi-beam data to reconstruct late glacial dynamics of grounded ice in McMurdo Sound and the western Ross Sea. The combined dataset suggest a dominance of ice flow toward the TAM in McMurdo Sound during all phases of glaciation, with thick, grounded ice at or near its maximum extent between 19.6 and 12.3 calibrated thousands of years before present (cal. ka). Our data show no significant advance of locally derived ice from the TAM into McMurdo Sound, consistent with the assertion that Late Pleistocene expansion of grounded ice in McMurdo Sound, and throughout the wider Ross Embayment, occurs in response to lower eustatic sea level and the resulting advance of marine-based outlet glaciers and ice streams (and perhaps also reduced oceanic heat flux), rather than local increases in precipitation and ice accumulation. Finally, when combined with allied data across the wider Ross Embayment, which show that widespread deglaciation outside McMurdo Sound did not commence until 13.1 ka, the implication is that retreat of grounded glacier ice in the Ross Embayment did not add significantly to SLR during Meltwater Pulse 1a (14.0-14.5 ka).

Source levels of social sounds in migrating humpback whales (Megaptera novaeangliae).

PubMed

Dunlop, Rebecca A; Cato, Douglas H; Noad, Michael J; Stokes, Dale M

2013-07-01

The source level of an animal sound is important in communication, since it affects the distance over which the sound is audible. Several measurements of source levels of whale sounds have been reported, but the accuracy of many is limited because the distance to the source and the acoustic transmission loss were estimated rather than measured. This paper presents measurements of source levels of social sounds (surface-generated and vocal sounds) of humpback whales from a sample of 998 sounds recorded from 49 migrating humpback whale groups. Sources were localized using a wide baseline five hydrophone array and transmission loss was measured for the site. Social vocalization source levels were found to range from 123 to 183 dB re 1 μPa @ 1 m with a median of 158 dB re 1 μPa @ 1 m. Source levels of surface-generated social sounds ("breaches" and "slaps") were narrower in range (133 to 171 dB re 1 μPa @ 1 m) but slightly higher in level (median of 162 dB re 1 μPa @ 1 m) compared to vocalizations. The data suggest that group composition has an effect on group vocalization source levels in that singletons and mother-calf-singing escort groups tend to vocalize at higher levels compared to other group compositions.

Occupational Noise Exposure among Toll Tellers at Toll Plaza in Malaysia

NASA Astrophysics Data System (ADS)

Azmi, Sharifah Nadya Syed; Dawal, Siti Zawiah Md; Ya, Tuan Mohammad Yusoff Shah Tuan; Saidin, Hamidi

2010-10-01

Toll tellers working at toll plaza have potential of exposure to high noise from the vehicles especially for the peak level of sound emitted by the heavy vehicles. However, occupational exposures in this workplace have not been adequately characterized and identified. Occupational noise exposure among toll tellers at toll plaza was assessed using Sound Level Meter, Noise Dosimeter and through questionnaire survey. These data were combined to estimate the work shift exposure level and health impacts to the toll tellers by using statistical analysis. Noise Dosimeter microphone was located at the hearing zone of the toll teller which working inside the toll booth and full-period measurements were collected for each work shift. The measurements were taken at 20 toll booths from 6.00 am to 2.00 pm for 5 days. 71 respondents participated in the survey to identify the symptoms of noise induced hearing loss and other health related problems among toll tellers. Results of this study indicated that occupational noise exposure among toll tellers for Mean Continuous Equivalent Level, Leq was 79.2±1.4 dB(A), Mean Maximum Level, Lmax was 107.8±3.6 dB(A) and Mean Peak Level, Lpeak was 136.6±9.9 dB. The Peak Level reported statistically significantly at 140 dB, the level of TLV recommended by ACGIH. The research findings indicated that the primary risk exposure to toll tellers comes from noise that emitted from heavy vehicles. Most of the toll tellers show symptoms of noise induced hearing loss and annoyed by the sources of noise at the toll plaza.

Design and Characterization of the UTIAS Anechoic Wind Tunnel

NASA Astrophysics Data System (ADS)

Chow, Derrick H. F.

The anechoic open-jet wind tunnel facility at the University of Toronto Institute for Aerospace Studies was updated and characterized to meet the needs of current and future aeroacoustic experiments. The wind tunnel inlet was resurfaced and flow-conditioning screens were redesigned to improve the freestream turbulence intensity to below 0.4% in the test section. The circular nozzle was replaced with a square secondary contraction that increased the maximum test section velocity to 75 m/s and improved flow uniformity to over 99% across a usable cross-sectional area of 500 mm x 500 mm. Acoustic baffles were installed in front of the wind tunnel inlet and foam wedges were installed in the anechoic chamber. The overall background sound pressure levels in the chamber were improved by 8-18 db over the range of operational freestream velocities. The anechoic chamber cut-off frequency is 170 Hz and the reverberation time for a 60 dB sound power decay is 0.032 s.

Observation of ice nucleation in acoustically levitated water drops

NASA Astrophysics Data System (ADS)

Lü, Y. J.; Xie, W. J.; Wei, B.

2005-10-01

The supercooling and nucleation of acoustically levitated water drops were investigated at two different sound pressure levels (SPL). These water drops were supercooled by 13to16K at the low SPL of 160.6dB, whereas their supercoolings varied from 5to11K at the high SPL of 164.4dB. The maximum supercooling obtained in the experiments is 32K. Statistical analyses based on the classical nucleation theory reveal that the occurrence of ice nucleation in water drops is mainly confined to the surface region under acoustic levitation conditions and the enlargement of drop surface area caused by the acoustic radiation pressure reduces water supercoolability remarkably. A comparison of the nucleation rates at the two SPLs indicates that the sound pressure can strengthen the surface-dominated nucleation of water drops. The acoustic stream around levitated water drops and the cavitation effect associated with ultrasonic field are the main factors that induce surface-dominated nucleation.

Comprehensive measures of sound exposures in cinemas using smart phones.

PubMed

Huth, Markus E; Popelka, Gerald R; Blevins, Nikolas H

2014-01-01

Sensorineural hearing loss from sound overexposure has a considerable prevalence. Identification of sound hazards is crucial, as prevention, due to a lack of definitive therapies, is the sole alternative to hearing aids. One subjectively loud, yet little studied, potential sound hazard is movie theaters. This study uses smart phones to evaluate their applicability as a widely available, validated sound pressure level (SPL) meter. Therefore, this study measures sound levels in movie theaters to determine whether sound levels exceed safe occupational noise exposure limits and whether sound levels in movie theaters differ as a function of movie, movie theater, presentation time, and seat location within the theater. Six smart phones with an SPL meter software application were calibrated with a precision SPL meter and validated as an SPL meter. Additionally, three different smart phone generations were measured in comparison to an integrating SPL meter. Two different movies, an action movie and a children's movie, were measured six times each in 10 different venues (n = 117). To maximize representativeness, movies were selected focusing on large release productions with probable high attendance. Movie theaters were selected in the San Francisco, CA, area based on whether they screened both chosen movies and to represent the largest variety of theater proprietors. Measurements were analyzed in regard to differences between theaters, location within the theater, movie, as well as presentation time and day as indirect indicator of film attendance. The smart phone measurements demonstrated high accuracy and reliability. Overall, sound levels in movie theaters do not exceed safe exposure limits by occupational standards. Sound levels vary significantly across theaters and demonstrated statistically significant higher sound levels and exposures in the action movie compared to the children's movie. Sound levels decrease with distance from the screen. However, no influence on time of day or day of the week as indirect indicator of film attendance could be found. Calibrated smart phones with an appropriate software application as used in this study can be utilized as a validated SPL meter. Because of the wide availability, smart phones in combination with the software application can provide high quantity recreational sound exposure measurements, which can facilitate the identification of potential noise hazards. Sound levels in movie theaters decrease with distance to the screen, but do not exceed safe occupational noise exposure limits. Additionally, there are significant differences in sound levels across movie theaters and movies, but not in presentation time.

Assessing the Underwater Acoustics of the World's Largest Vibration Hammer (OCTA-KONG) and Its Potential Effects on the Indo-Pacific Humpbacked Dolphin (Sousa chinensis)

PubMed Central

Wang, Zhitao; Wu, Yuping; Duan, Guoqin; Cao, Hanjiang; Liu, Jianchang; Wang, Kexiong; Wang, Ding

2014-01-01

Anthropogenic noise in aquatic environments is a worldwide concern due to its potential adverse effects on the environment and aquatic life. The Hongkong-Zhuhai-Macao Bridge is currently under construction in the Pearl River Estuary, a hot spot for the Indo-Pacific humpbacked dolphin (Sousa chinensis) in China. The OCTA-KONG, the world's largest vibration hammer, is being used during this construction project to drive or extract steel shell piles 22 m in diameter. This activity poses a substantial threat to marine mammals, and an environmental assessment is critically needed. The underwater acoustic properties of the OCTA-KONG were analyzed, and the potential impacts of the underwater acoustic energy on Sousa, including auditory masking and physiological impacts, were assessed. The fundamental frequency of the OCTA-KONG vibration ranged from 15 Hz to 16 Hz, and the noise increments were below 20 kHz, with a dominant frequency and energy below 10 kHz. The resulting sounds are most likely detectable by Sousa over distances of up to 3.5 km from the source. Although Sousa clicks do not appear to be adversely affected, Sousa whistles are susceptible to auditory masking, which may negatively impact this species' social life. Therefore, a safety zone with a radius of 500 m is proposed. Although the zero-to-peak source level (SL) of the OCTA-KONG was lower than the physiological damage level, the maximum root-mean-square SL exceeded the cetacean safety exposure level on several occasions. Moreover, the majority of the unweighted cumulative source sound exposure levels (SSELs) and the cetacean auditory weighted cumulative SSELs exceeded the acoustic threshold levels for the onset of temporary threshold shift, a type of potentially recoverable auditory damage resulting from prolonged sound exposure. These findings may aid in the identification and design of appropriate mitigation methods, such as the use of air bubble curtains, “soft start” and “power down” techniques. PMID:25338113

[Evaluation of the risk on hearing loss at soldiers].

PubMed

Konopka, Wiesław; Olszewski, Jurek; Straszyński, Piotr

2006-01-01

Noise produced by weapons may be harmful to soldiers during military service. Exposure to impulse noise during compulsory military service depends on the number of shots, explosion impulses, distance of injured ear from causal firearm as well as on the use of hearing protectors. Weapons produce impulse noises, which are characterized by peak pressure level and frequency. The purpose of this work was to calculate and estimate risk on hearing at soldiers during one year of the military service. The study comparised three groups of soldiers with different kind of exposure to noise divided according total noise exposure. In order to evaluate the amount of the exposure to impulse noise the total level of noise and the spectrum analysis were performed for all types of weapons, which were used during military service. The equivalent continuous A-weighted sound pressure level, L A eq, Te [dB], maximum A-weighted sound pressure level, L A max [dB] and C weighted peak sound pressure level, L C peak [dB] were measured. The highest total exposure to noise concerned group I (2222,9 kPa(2)/s for right ear and 22212,8 kPa(2)/s for left one) with total exposure time 248,3 minutes. In the II group estimated total exposure to noise was 611,8 kPa(2)/s for right ear and 743,6 kPa(2)/s for left one. In the III group least exposed to noise, estimated total exposure to noise was 103 kPa(2)/s for right ear and 109 kPa(2)/s for left one with total time exposure 17,8 minutes. Difference between groups is dependent on kind of military service. Estimated exposure to weapons noise may prevent soldiers before hearing loss. We did not notice differences between sites of ears.

Assessing the underwater acoustics of the world's largest vibration hammer (OCTA-KONG) and its potential effects on the Indo-Pacific humpbacked dolphin (Sousa chinensis).

PubMed

Wang, Zhitao; Wu, Yuping; Duan, Guoqin; Cao, Hanjiang; Liu, Jianchang; Wang, Kexiong; Wang, Ding

2014-01-01

Anthropogenic noise in aquatic environments is a worldwide concern due to its potential adverse effects on the environment and aquatic life. The Hongkong-Zhuhai-Macao Bridge is currently under construction in the Pearl River Estuary, a hot spot for the Indo-Pacific humpbacked dolphin (Sousa chinensis) in China. The OCTA-KONG, the world's largest vibration hammer, is being used during this construction project to drive or extract steel shell piles 22 m in diameter. This activity poses a substantial threat to marine mammals, and an environmental assessment is critically needed. The underwater acoustic properties of the OCTA-KONG were analyzed, and the potential impacts of the underwater acoustic energy on Sousa, including auditory masking and physiological impacts, were assessed. The fundamental frequency of the OCTA-KONG vibration ranged from 15 Hz to 16 Hz, and the noise increments were below 20 kHz, with a dominant frequency and energy below 10 kHz. The resulting sounds are most likely detectable by Sousa over distances of up to 3.5 km from the source. Although Sousa clicks do not appear to be adversely affected, Sousa whistles are susceptible to auditory masking, which may negatively impact this species' social life. Therefore, a safety zone with a radius of 500 m is proposed. Although the zero-to-peak source level (SL) of the OCTA-KONG was lower than the physiological damage level, the maximum root-mean-square SL exceeded the cetacean safety exposure level on several occasions. Moreover, the majority of the unweighted cumulative source sound exposure levels (SSELs) and the cetacean auditory weighted cumulative SSELs exceeded the acoustic threshold levels for the onset of temporary threshold shift, a type of potentially recoverable auditory damage resulting from prolonged sound exposure. These findings may aid in the identification and design of appropriate mitigation methods, such as the use of air bubble curtains, "soft start" and "power down" techniques.

The Role of Environmental Shear and Thermodynamic Conditions in Determining the Structure and Evolution of Mesoscale Convective Systems during TOGA COARE.

NASA Astrophysics Data System (ADS)

Lemone, Margaret A.; Zipser, Edward J.; Trier, Stanley B.

1998-12-01

A collection of case studies is used to elucidate the influence of environmental soundings on the structure and evolution of the convection in the mesoscale convective systems sampled by the turboprop aircraft in the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE). The soundings were constructed primarily from aircraft data below 5-6 km and primarily from radiosonde data at higher altitudes.The well-documented role of the vertical shear of the horizontal wind in determining the mesoscale structure of tropical convection is confirmed and extended. As noted by earlier investigators, nearly all convective bands occurring in environments with appreciable shear below a low-level wind maximum are oriented nearly normal to the shear beneath the wind maximum and propagate in the direction of the low-level shear at a speed close to the wind maximum; when there is appreciable shear at middle levels (800-400 mb), convective bands form parallel to the shear. With appreciable shear at both levels, the lower-level shear determines the orientation of the primary convective bands. If the midlevel shear is opposite the low-level shear, secondary bands parallel to the midlevel shear will extend rearward from the primary band in later stages of its evolution; if the midlevel shear is 90 degrees to the low-level shear, the primary band will retain its two-dimensional mesoscale structure. Convection has no obvious mesoscale organization on days with little shear or days with widespread convection.Environmental temperatures and humidities have no obvious effect on the mesoscale convective pattern, but they affect COARE convection in other ways. The high tops of COARE convection are related to high parcel equilibrium levels, which approach 100 mb in some cases. Convective available potential energies are larger than those in the GARP (Global Atmospheric Research Program) Atlantic Tropical Experiment (GATE) mainly because of the higher equilibrium levels. The buoyancy integrated over the lowest 500 mb is similar for the two experiments. Convective inihibitions are small, enabling convection to propagate with only weak forcing. Comparison of slow-moving shear-parallel bands in COARE and GATE suggests that lower relative humidities between the top of the mixed layer and 500 mb can shorten their lifetimes significantly.COARE mesoscale organization and evolution differs from what was observed in GATE. Less-organized convection is more common in COARE. Of the convective bands observed, a greater fraction in COARE are faster-moving, shear-perpendicular squall lines. GATE slow-moving lines tend to be longer lived than those for COARE. The differences are probably traceable to differences in environmental shear and relative humidity, respectively.

Radiated BPF sound measurement of centrifugal compressor

NASA Astrophysics Data System (ADS)

Ohuchida, S.; Tanaka, K.

2013-12-01

A technique to measure radiated BPF sound from an automotive turbocharger compressor impeller is proposed in this paper. Where there are high-level background noises in the measurement environment, it is difficult to discriminate the target component from the background. Since the effort of measuring BPF sound was taken in a room with such condition in this study, no discrete BPF peak was initially found on the sound spectrum. Taking its directionality into consideration, a microphone covered with a parabolic cone was selected and using this technique, the discrete peak of BPF was clearly observed. Since the level of measured sound was amplified due to the area-integration effect, correction was needed to obtain the real level. To do so, sound measurements with and without a parabolic cone were conducted for the fixed source and their level differences were used as correction factors. Consideration is given to the sound propagation mechanism utilizing measured BPF as well as the result of a simple model experiment. The present method is generally applicable to sound measurements conducted with a high level of background noise.

Hearing Tests on Mobile Devices: Evaluation of the Reference Sound Level by Means of Biological Calibration.

PubMed

Masalski, Marcin; Kipiński, Lech; Grysiński, Tomasz; Kręcicki, Tomasz

2016-05-30

Hearing tests carried out in home setting by means of mobile devices require previous calibration of the reference sound level. Mobile devices with bundled headphones create a possibility of applying the predefined level for a particular model as an alternative to calibrating each device separately. The objective of this study was to determine the reference sound level for sets composed of a mobile device and bundled headphones. Reference sound levels for Android-based mobile devices were determined using an open access mobile phone app by means of biological calibration, that is, in relation to the normal-hearing threshold. The examinations were conducted in 2 groups: an uncontrolled and a controlled one. In the uncontrolled group, the fully automated self-measurements were carried out in home conditions by 18- to 35-year-old subjects, without prior hearing problems, recruited online. Calibration was conducted as a preliminary step in preparation for further examination. In the controlled group, audiologist-assisted examinations were performed in a sound booth, on normal-hearing subjects verified through pure-tone audiometry, recruited offline from among the workers and patients of the clinic. In both the groups, the reference sound levels were determined on a subject's mobile device using the Bekesy audiometry. The reference sound levels were compared between the groups. Intramodel and intermodel analyses were carried out as well. In the uncontrolled group, 8988 calibrations were conducted on 8620 different devices representing 2040 models. In the controlled group, 158 calibrations (test and retest) were conducted on 79 devices representing 50 models. Result analysis was performed for 10 most frequently used models in both the groups. The difference in reference sound levels between uncontrolled and controlled groups was 1.50 dB (SD 4.42). The mean SD of the reference sound level determined for devices within the same model was 4.03 dB (95% CI 3.93-4.11). Statistically significant differences were found across models. Reference sound levels determined in the uncontrolled group are comparable to the values obtained in the controlled group. This validates the use of biological calibration in the uncontrolled group for determining the predefined reference sound level for new devices. Moreover, due to a relatively small deviation of the reference sound level for devices of the same model, it is feasible to conduct hearing screening on devices calibrated with the predefined reference sound level.

The EarLens System: New Sound Transduction Methods

PubMed Central

Perkins, Rodney; Fay, Jonathan P.; Rucker, Paul; Rosen, Micha; Olson, Lisa; Puria, Sunil

2010-01-01

The hypothesis is tested that an open-canal hearing device, with a microphone in the ear canal, can be designed to provide amplification over a wide bandwidth and without acoustic feedback. In the design under consideration, a transducer consisting of a thin silicone platform with an embedded magnet is placed directly on the tympanic membrane. Sound picked up by a microphone in the ear canal, including sound-localization cues thought to be useful for speech perception in noisy environments, is processed and amplified, and then used to drive a coil near the tympanic-membrane transducer. The perception of sound results from the vibration of the transducer in response the electromagnetic field produced by the coil. Sixteen subjects (ranging from normal-hearing to moderately hearing-impaired) wore this transducer for up to a ten-month period, and were monitored for any adverse reactions. Three key functional characteristics were measured: 1) the maximum equivalent pressure output (MEPO) of the transducer; 2) the feedback gain margin (GM), which describes the maximum allowable gain before feedback occurs; and 3) the tympanic-membrane damping effect (DTM), which describes the change in hearing level due to placement of the transducer on the eardrum. Results indicate that the tympanic-membrane transducer remains in place and is well tolerated. The system can produce sufficient output to reach threshold for those with as much as 60 dBHL of hearing impairment for up to 8 kHz in 86% of the study population, and up to 11.2 kHz in 50% of the population. The feedback gain margin is on average 30 dB except at the ear canal resonance frequencies of 3 and 9 kHz, where the average was reduced to 12 dB and 23 dB respectively. The average value of DTM is close to 0 dB everywhere except in the 2–4 kHz range, where it peaks at 8 dB. A new alternative system that uses photonic energy to transmit both the signal and power to a photodiode and micro-actuator on an EarLens platform is also described. PMID:20116419

Analysis of sound pressure levels emitted by children's toys.

PubMed

Sleifer, Pricila; Gonçalves, Maiara Santos; Tomasi, Marinês; Gomes, Erissandra

2013-06-01

To verify the levels of sound pressure emitted by non-certified children's toys. Cross-sectional study of sound toys available at popular retail stores of the so-called informal sector. Electronic, mechanical, and musical toys were analyzed. The measurement of each product was carried out by an acoustic engineer in an acoustically isolated booth, by a decibel meter. To obtain the sound parameters of intensity and frequency, the toys were set to produce sounds at a distance of 10 and 50cm from the researcher's ear. The intensity of sound pressure [dB(A)] and the frequency in hertz (Hz) were measured. 48 toys were evaluated. The mean sound pressure 10cm from the ear was 102±10 dB(A), and at 50cm, 94±8 dB(A), with p<0.05. The level of sound pressure emitted by the majority of toys was above 85dB(A). The frequency ranged from 413 to 6,635Hz, with 56.3% of toys emitting frequency higher than 2,000Hz. The majority of toys assessed in this research emitted a high level of sound pressure.

Visualizing Sound: Demonstrations to Teach Acoustic Concepts

NASA Astrophysics Data System (ADS)

Rennoll, Valerie

Interference, a phenomenon in which two sound waves superpose to form a resultant wave of greater or lower amplitude, is a key concept when learning about the physics of sound waves. Typical interference demonstrations involve students listening for changes in sound level as they move throughout a room. Here, new tools are developed to teach this concept that provide a visual component, allowing individuals to see changes in sound level on a light display. This is accomplished using a microcontroller that analyzes sound levels collected by a microphone and displays the sound level in real-time on an LED strip. The light display is placed on a sliding rail between two speakers to show the interference occurring between two sound waves. When a long-exposure photograph is taken of the light display being slid from one end of the rail to the other, a wave of the interference pattern can be captured. By providing a visual component, these tools will help students and the general public to better understand interference, a key concept in acoustics.

Can joint sound assess soft and hard endpoints of the Lachman test?: A preliminary study.

PubMed

Hattori, Koji; Ogawa, Munehiro; Tanaka, Kazunori; Matsuya, Ayako; Uematsu, Kota; Tanaka, Yasuhito

2016-05-12

The Lachman test is considered to be a reliable physical examination for anterior cruciate ligament (ACL) injury. Patients with a damaged ACL demonstrate a soft endpoint feeling. However, examiners judge the soft and hard endpoints subjectively. The purpose of our study was to confirm objective performance of the Lachman test using joint auscultation. Human and porcine knee joints were examined. Knee joint sound during the Lachman test (Lachman sound) was analyzed by fast Fourier transformation. As quantitative indices of Lachman sound, the peak sound as the maximum relative amplitude (acoustic pressure) and its frequency were used. The mean Lachman peak sound for healthy volunteer knees was 86.9 ± 12.9 Hz in frequency and -40 ± 2.5 dB in acoustic pressure. The mean Lachman peak sound for intact porcine knees was 84.1 ± 9.4 Hz and -40.5 ± 1.7 dB. Porcine knees with ACL deficiency had a soft endpoint feeling during the Lachman test. The Lachman peak sounds of porcine knees with ACL deficiency were dispersed into four distinct groups, with center frequencies of around 40, 160, 450, and 1600. The Lachman peak sound was capable of assessing soft and hard endpoints of the Lachman test objectively.

Behavioral response of manatees to variations in environmental sound levels

USGS Publications Warehouse

Miksis-Olds, Jennifer L.; Wagner, Tyler

2011-01-01

Florida manatees (Trichechus manatus latirostris) inhabit coastal regions because they feed on the aquatic vegetation that grows in shallow waters, which are the same areas where human activities are greatest. Noise produced from anthropogenic and natural sources has the potential to affect these animals by eliciting responses ranging from mild behavioral changes to extreme aversion. Sound levels were calculated from recordings made throughout behavioral observation periods. An information theoretic approach was used to investigate the relationship between behavior patterns and sound level. Results indicated that elevated sound levels affect manatee activity and are a function of behavioral state. The proportion of time manatees spent feeding and milling changed in response to sound level. When ambient sound levels were highest, more time was spent in the directed, goal-oriented behavior of feeding, whereas less time was spent engaged in undirected behavior such as milling. This work illustrates how shifts in activity of individual manatees may be useful parameters for identifying impacts of noise on manatees and might inform population level effects.

Sound-localization experiments with barn owls in virtual space: influence of broadband interaural level different on head-turning behavior.

PubMed

Poganiatz, I; Wagner, H

2001-04-01

Interaural level differences play an important role for elevational sound localization in barn owls. The changes of this cue with sound location are complex and frequency dependent. We exploited the opportunities offered by the virtual space technique to investigate the behavioral relevance of the overall interaural level difference by fixing this parameter in virtual stimuli to a constant value or introducing additional broadband level differences to normal virtual stimuli. Frequency-specific monaural cues in the stimuli were not manipulated. We observed an influence of the broadband interaural level differences on elevational, but not on azimuthal sound localization. Since results obtained with our manipulations explained only part of the variance in elevational turning angle, we conclude that frequency-specific cues are also important. The behavioral consequences of changes of the overall interaural level difference in a virtual sound depended on the combined interaural time difference contained in the stimulus, indicating an indirect influence of temporal cues on elevational sound localization as well. Thus, elevational sound localization is influenced by a combination of many spatial cues including frequency-dependent and temporal features.

Compact stars

NASA Astrophysics Data System (ADS)

Estevez-Delgado, Gabino; Estevez-Delgado, Joaquin

2018-05-01

An analysis and construction is presented for a stellar model characterized by two parameters (w, n) associated with the compactness ratio and anisotropy, respectively. The reliability range for the parameter w ≤ 1.97981225149 corresponds with a compactness ratio u ≤ 0.2644959374, the density and pressures are positive, regular and monotonic decrescent functions, the radial and tangential speed of sound are lower than the light speed, moreover, than the plausible stability. The behavior of the speeds of sound are determinate for the anisotropy parameter n, admitting a subinterval where the speeds are monotonic crescent functions and other where we have monotonic decrescent functions for the same speeds, both cases describing a compact object that is also potentially stable. In the bigger value for the observational mass M = 2.05 M⊙ and radii R = 12.957 Km for the star PSR J0348+0432, the model indicates that the maximum central density ρc = 1.283820319 × 1018 Kg/m3 corresponds to the maximum value of the anisotropy parameter and the radial and tangential speed of the sound are monotonic decrescent functions.

Classification of pulmonary pathology from breath sounds using the wavelet packet transform and an extreme learning machine.

PubMed

Palaniappan, Rajkumar; Sundaraj, Kenneth; Sundaraj, Sebastian; Huliraj, N; Revadi, S S

2017-06-08

Auscultation is a medical procedure used for the initial diagnosis and assessment of lung and heart diseases. From this perspective, we propose assessing the performance of the extreme learning machine (ELM) classifiers for the diagnosis of pulmonary pathology using breath sounds. Energy and entropy features were extracted from the breath sound using the wavelet packet transform. The statistical significance of the extracted features was evaluated by one-way analysis of variance (ANOVA). The extracted features were inputted into the ELM classifier. The maximum classification accuracies obtained for the conventional validation (CV) of the energy and entropy features were 97.36% and 98.37%, respectively, whereas the accuracies obtained for the cross validation (CRV) of the energy and entropy features were 96.80% and 97.91%, respectively. In addition, maximum classification accuracies of 98.25% and 99.25% were obtained for the CV and CRV of the ensemble features, respectively. The results indicate that the classification accuracy obtained with the ensemble features was higher than those obtained with the energy and entropy features.

Propeller installation effects on turboprop aircraft acoustics

NASA Astrophysics Data System (ADS)

Chirico, Giulia; Barakos, George N.; Bown, Nicholas

2018-06-01

Propeller installation options for a twin-engined turboprop aircraft are evaluated at cruise conditions, aiming to identify the quieter configuration. Computational fluid dynamics is used to investigate the near-field acoustics and transfer functions are employed to estimate the interior cabin noise. Co-rotating and counter-rotating installation options are compared. The effect of propeller synchrophasing is also considered. The employed method captures the complexity of the acoustic field generated by the interactions of the propeller sound fields among each other and with the airframe, showing also the importance of simulating the whole problem to predict the actual noise on a flying aircraft. Marked differences among the various layouts are observed. The counter-rotating top-in option appears the best in terms of acoustics, the top-out propeller rotation leading to louder noise because of inflow conditions and the occurrence of constructive acoustic interferences. Synchrophasing is shown to be beneficial for co-rotating propellers, specially regarding the interior noise, because of favorable effects in the interaction between the propeller direct sound field and the noise due to the airframe. An angle closer to the maximum relative blade shift was found to be the best choice, yielding, however, higher sound levels than those provided by the counter-rotating top-in layout.

Optimization of Sound Absorbers Number and Placement in an Enclosed Room by Finite Element Simulation

NASA Astrophysics Data System (ADS)

Lau, S. F.; Zainulabidin, M. H.; Yahya, M. N.; Zaman, I.; Azmir, N. A.; Madlan, M. A.; Ismon, M.; Kasron, M. Z.; Ismail, A. E.

2017-10-01

Giving a room proper acoustic treatment is both art and science. Acoustic design brings comfort in the built environment and reduces noise level by using sound absorbers. There is a need to give a room acoustic treatment by installing absorbers in order to decrease the reverberant sound. However, they are usually high in price which cost much for installation and there is no system to locate the optimum number and placement of sound absorbers. It would be a waste if the room is overly treated with absorbers or cause improper treatment if the room is treated with insufficient absorbers. This study aims to determine the amount of sound absorbers needed and optimum location of sound absorbers placement in order to reduce the overall sound pressure level in specified room by using ANSYS APDL software. The size of sound absorbers needed is found to be 11 m 2 by using Sabine equation and different unit sets of absorbers are applied on walls, each with the same total areas to investigate the best configurations. All three sets (single absorber, 11 absorbers and 44 absorbers) has successfully treating the room by reducing the overall sound pressure level. The greatest reduction in overall sound pressure level is that of 44 absorbers evenly distributed around the walls, which has reduced as much as 24.2 dB and the least effective configuration is single absorber whereby it has reduced the overall sound pressure level by 18.4 dB.

Noise level in intensive care units of a public university hospital in Santa Marta (Colombia).

PubMed

Garrido Galindo, A P; Camargo Caicedo, Y; Vélez-Pereira, A M

2016-10-01

To evaluate the noise level in adult, pediatric and neonatal intensive care units of a university hospital in the city of Santa Marta (Colombia). A descriptive, observational, non-interventional study with follow-up over time was carried out. Continuous sampling was conducted for 20 days for each unit using a type i sound level meter, filter frequency in A weighting and Fast mode. We recorded the maximum values, the 90th percentile as background noise, and the continuous noise level. The mean hourly levels in the adult unit varied between 57.40±1.14-63.47±2.13dBA, with a maximum between 71.55±2.32-77.22±1.94dBA, and a background noise between 53.51±1.16-60.26±2.10dBA; in the pediatric unit the mean hourly levels varied between 57.07±3.07-65.72±2.46dBA, with a maximum of 68.69±3.57-79.06±2.34dBA, and a background noise between 53.33±3.54-61.96±2.85dBA; the neonatal unit in turn presented mean hourly values between 59.54±2.41-65.33±1.77dBA, with a maximum value between 67.20±2.13-77.65±3.74dBA, and a background noise between 55.02±2.03-58.70±1.95dBA. Analysis of variance revealed a significant difference between the hourly values and between the different units, with the time of day exhibiting a greater influence. The type of unit affects the noise levels in intensive care units, the pediatric unit showing the highest values and the adult unit the lowest values. However, the parameter exerting the greatest influence upon noise level is the time of day, with higher levels in the morning and evening, and lower levels at night and in the early morning. Copyright © 2015 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

49 CFR 227.115 - Hearing protectors.

Code of Federal Regulations, 2011 CFR

2011-10-01

... employees exposed to sound levels that meet or exceed the action level. (c) Required use at action level. A railroad shall require the use of hearing protectors when an employee is exposed to sound levels that meet... hearing protectors when an employee is exposed to sound levels equivalent to an 8-hour TWA of 90 dB(A) or...

Noise level in a neonatal intensive care unit in Santa Marta - Colombia.

PubMed Central

Garrido Galindo, Angélica Patricia; Velez-Pereira, Andres M

2017-01-01

Abstract Introduction: The environment of neonatal intensive care units is influenced by numerous sources of noise emission, which contribute to raise the noise levels, and may cause hearing impairment and other physiological and psychological changes on the newborn, as well as problems with care staff. Objective: To evaluate the level and sources of noise in the neonatal intensive care unit. Methods: Sampled for 20 consecutive days every 60 seconds in A-weighting curves and fast mode with a Type I sound level meter. Recorded the average, maximum and minimum, and the 10th, 50th and 90th percentiles. The values are integrated into hours and work shift, and studied by analysis of variance. The sources were characterized in thirds of octaves. Results: The average level was 64.00 ±3.62 dB(A), with maximum of 76.04 ±5.73 dB(A), minimum of 54.84 ±2.61dB(A), and background noise of 57.95 ±2.83 dB(A). We found four sources with levels between 16.8-63.3 dB(A). Statistical analysis showed significant differences between the hours and work shift, with higher values in the early hours of the day. Conclusion: The values presented exceed the standards suggested by several organizations. The sources identified and measured recorded high values in low frequencies. PMID:29213154

Compressed air noise reductions from using advanced air gun nozzles in research and development environments.

PubMed

Prieve, Kurt; Rice, Amanda; Raynor, Peter C

2017-08-01

The aims of this study were to evaluate sound levels produced by compressed air guns in research and development (R&D) environments, replace conventional air gun models with advanced noise-reducing air nozzles, and measure changes in sound levels to assess the effectiveness of the advanced nozzles as engineering controls for noise. Ten different R&D manufacturing areas that used compressed air guns were identified and included in the study. A-weighted sound level and Z-weighted octave band measurements were taken simultaneously using a single instrument. In each area, three sets of measurements, each lasting for 20 sec, were taken 1 m away and perpendicular to the air stream of the conventional air gun while a worker simulated typical air gun work use. Two different advanced noise-reducing air nozzles were then installed. Sound level and octave band data were collected for each of these nozzles using the same methods as for the original air guns. Both of the advanced nozzles provided sound level reductions of about 7 dBA, on average. The highest noise reductions measured were 17.2 dBA for one model and 17.7 dBA for the other. In two areas, the advanced nozzles yielded no sound level reduction, or they produced small increases in sound level. The octave band data showed strong similarities in sound level among all air gun nozzles within the 10-1,000 Hz frequency range. However, the advanced air nozzles generally had lower noise contributions in the 1,000-20,000 Hz range. The observed decreases at these higher frequencies caused the overall sound level reductions that were measured. Installing new advanced noise-reducing air nozzles can provide large sound level reductions in comparison to existing conventional nozzles, which has direct benefit for hearing conservation efforts.

Underwater noise from three types of offshore wind turbines: estimation of impact zones for harbor porpoises and harbor seals.

PubMed

Tougaard, Jakob; Henriksen, Oluf Damsgaard; Miller, Lee A

2009-06-01

Underwater noise was recorded from three different types of wind turbines in Denmark and Sweden (Middelgrunden, Vindeby, and Bockstigen-Valar) during normal operation. Wind turbine noise was only measurable above ambient noise at frequencies below 500 Hz. Total sound pressure level was in the range 109-127 dB re 1 microPa rms, measured at distances between 14 and 20 m from the foundations. The 1/3-octave noise levels were compared with audiograms of harbor seals and harbor porpoises. Maximum 1/3-octave levels were in the range 106-126 dB re 1 microPa rms. Maximum range of audibility was estimated under two extreme assumptions on transmission loss (3 and 9 dB per doubling of distance, respectively). Audibility was low for harbor porpoises extending 20-70 m from the foundation, whereas audibility for harbor seals ranged from less than 100 m to several kilometers. Behavioral reactions of porpoises to the noise appear unlikely except if they are very close to the foundations. However, behavioral reactions from seals cannot be excluded up to distances of a few hundred meters. It is unlikely that the noise reaches dangerous levels at any distance from the turbines and the noise is considered incapable of masking acoustic communication by seals and porpoises.

Handbook of aircraft noise metrics

NASA Technical Reports Server (NTRS)

Bennett, R. L.; Pearsons, K. S.

1981-01-01

Information is presented on 22 noise metrics that are associated with the measurement and prediction of the effects of aircraft noise. Some of the instantaneous frequency weighted sound level measures, such as A-weighted sound level, are used to provide multiple assessment of the aircraft noise level. Other multiple event metrics, such as day-night average sound level, were designed to relate sound levels measured over a period of time to subjective responses in an effort to determine compatible land uses and aid in community planning. The various measures are divided into: (1) instantaneous sound level metrics; (2) duration corrected single event metrics; (3) multiple event metrics; and (4) speech communication metrics. The scope of each measure is examined in terms of its: definition, purpose, background, relationship to other measures, calculation method, example, equipment, references, and standards.

Handbook of aircraft noise metrics

NASA Astrophysics Data System (ADS)

Bennett, R. L.; Pearsons, K. S.

1981-03-01

Information is presented on 22 noise metrics that are associated with the measurement and prediction of the effects of aircraft noise. Some of the instantaneous frequency weighted sound level measures, such as A-weighted sound level, are used to provide multiple assessment of the aircraft noise level. Other multiple event metrics, such as day-night average sound level, were designed to relate sound levels measured over a period of time to subjective responses in an effort to determine compatible land uses and aid in community planning. The various measures are divided into: (1) instantaneous sound level metrics; (2) duration corrected single event metrics; (3) multiple event metrics; and (4) speech communication metrics. The scope of each measure is examined in terms of its: definition, purpose, background, relationship to other measures, calculation method, example, equipment, references, and standards.

Evaluating standard airborne sound insulation measures in terms of annoyance, loudness, and audibility ratings.

PubMed

Park, H K; Bradley, J S

2009-07-01

This paper reports the results of an evaluation of the merits of standard airborne sound insulation measures with respect to subjective ratings of the annoyance and loudness of transmitted sounds. Subjects listened to speech and music sounds modified to represent transmission through 20 different walls with sound transmission class (STC) ratings from 34 to 58. A number of variations in the standard measures were also considered. These included variations in the 8-dB rule for the maximum allowed deficiency in the STC measure as well as variations in the standard 32-dB total allowed deficiency. Several spectrum adaptation terms were considered in combination with weighted sound reduction index (R(w)) values as well as modifications to the range of included frequencies in the standard rating contour. A STC measure without an 8-dB rule and an R(w) rating with a new spectrum adaptation term were better predictors of annoyance and loudness ratings of speech sounds. R(w) ratings with one of two modified C(tr) spectrum adaptation terms were better predictors of annoyance and loudness ratings of transmitted music sounds. Although some measures were much better predictors of responses to one type of sound than were the standard STC and R(w) values, no measure was remarkably improved for predicting annoyance and loudness ratings of both music and speech sounds.

Consumption demand of juvenile pink salmon in Prince William Sound and the coastal Gulf of Alaska in relation to prey biomass

NASA Astrophysics Data System (ADS)

Cross, Alison D.; Beauchamp, David A.; Armstrong, Janet L.; Blikshteyn, Mikhail; Boldt, Jennifer L.; Davis, Nancy D.; Haldorson, Lewis J.; Moss, Jamal H.; Myers, Katherine W.; Walker, Robert V.

2005-01-01

Prince William Sound hatcheries release over 600 million pink salmon ( Oncorhynchus gorbuscha) fry each year. The effect of the additional consumption demand by hatchery fish on prey biomass in Prince William Sound and the coastal Gulf of Alaska is unknown. The objectives of this study were to: (1) use bioenergetics models to compare spatial and temporal variation in the consumption demand and growth efficiency of hatchery and wild juvenile pink salmon in Prince William Sound and the coastal Gulf of Alaska between May and October 2001; and (2) compare localized population-level consumption in each region to the standing stock biomass of coexisting prey. In order to achieve observed growth, juvenile pink salmon consumed at 64-107% of their theoretical maximum consumption rate. Individual juvenile pink salmon consumed an average of 366.5 g of prey from marine entry through October of their first growing season. Growth efficiency ranged from 18.9% to 33.8% over the model simulation period. Juvenile salmon that migrated to the Gulf of Alaska grew more efficiently than those that remained in Prince William Sound until August, but after August juvenile salmon in Prince William Sound grew more efficiently than those in the Gulf of Alaska due to differences in prey quality between regions. Temperatures did not vary much between regions; thus differences in the thermal experience of juvenile pink salmon did not affect growth, consumption, and growth efficiency as much as the effects of different prey quality. Consumption demand by juvenile pink salmon exceeded the average standing stock biomass of key prey (large copepods, pteropods, hyperiid amphipods, and larvaceans) during some months. Our results are consistent with advection and production of these prey replenishing the forage base, or the reliance of individual pink salmon on high-density prey patches that occur at finer temporal scales than we were capable of sampling.

Calibration of Clinical Audio Recording and Analysis Systems for Sound Intensity Measurement.

PubMed

Maryn, Youri; Zarowski, Andrzej

2015-11-01

Sound intensity is an important acoustic feature of voice/speech signals. Yet recordings are performed with different microphone, amplifier, and computer configurations, and it is therefore crucial to calibrate sound intensity measures of clinical audio recording and analysis systems on the basis of output of a sound-level meter. This study was designed to evaluate feasibility, validity, and accuracy of calibration methods, including audiometric speech noise signals and human voice signals under typical speech conditions. Calibration consisted of 3 comparisons between data from 29 measurement microphone-and-computer systems and data from the sound-level meter: signal-specific comparison with audiometric speech noise at 5 levels, signal-specific comparison with natural voice at 3 levels, and cross-signal comparison with natural voice at 3 levels. Intensity measures from recording systems were then linearly converted into calibrated data on the basis of these comparisons, and validity and accuracy of calibrated sound intensity were investigated. Very strong correlations and quasisimilarity were found between calibrated data and sound-level meter data across calibration methods and recording systems. Calibration of clinical sound intensity measures according to this method is feasible, valid, accurate, and representative for a heterogeneous set of microphones and data acquisition systems in real-life circumstances with distinct noise contexts.

Noise exposure estimates of urban MP3 player users.

PubMed

Levey, Sandra; Levey, Tania; Fligor, Brian J

2011-02-01

To examine the sound level and duration of use of personal listening devices (PLDs) by 189 college students, ages 18-53 years, as they entered a New York City college campus, to determine whether noise exposure from PLDs was in excess of recommended exposure limits and what factors might influence exposure. Free-field equivalent sound levels from PLD headphones were measured on a mannequin with a calibrated sound level meter. Participants reported demographic information, whether they had just come off the subway, the type of PLD and earphones used, and duration per day and days per week they used their PLDs. Based on measured free-field equivalent sound levels from PLD headphones and the reported PLD use, per day 58.2% of participants exceeded 85 dB A-weighted 8-hr equivalent sound levels (L(Aeq)), and per week 51.9% exceeded 85 dB A-weighted 40-hr equivalent continuous sound levels (L(Awkn)). The majority of PLD users exceeded recommended sound exposure limits, suggesting that they were at increased risk for noise-induced hearing loss. Analyses of the demographics of these participants and mode of transportation to campus failed to indicate any particular gender differences in PLD use or in mode of transportation influencing sound exposure.

Modelling sound propagation in the Southern Ocean to estimate the acoustic impact of seismic research surveys on marine mammals

NASA Astrophysics Data System (ADS)

Breitzke, Monika; Bohlen, Thomas

2010-05-01

Modelling sound propagation in the ocean is an essential tool to assess the potential risk of air-gun shots on marine mammals. Based on a 2.5-D finite-difference code a full waveform modelling approach is presented, which determines both sound exposure levels of single shots and cumulative sound exposure levels of multiple shots fired along a seismic line. Band-limited point source approximations of compact air-gun clusters deployed by R/V Polarstern in polar regions are used as sound sources. Marine mammals are simulated as static receivers. Applications to deep and shallow water models including constant and depth-dependent sound velocity profiles of the Southern Ocean show dipole-like directivities in case of single shots and tubular cumulative sound exposure level fields beneath the seismic line in case of multiple shots. Compared to a semi-infinite model an incorporation of seafloor reflections enhances the seismically induced noise levels close to the sea surface. Refraction due to sound velocity gradients and sound channelling in near-surface ducts are evident, but affect only low to moderate levels. Hence, exposure zone radii derived for different hearing thresholds are almost independent of the sound velocity structure. With decreasing thresholds radii increase according to a spherical 20 log10 r law in case of single shots and according to a cylindrical 10 log10 r law in case of multiple shots. A doubling of the shot interval diminishes the cumulative sound exposure levels by -3 dB and halves the radii. The ocean bottom properties only slightly affect the radii in shallow waters, if the normal incidence reflection coefficient exceeds 0.2.

The sound exposure of the audience at a music festival.

PubMed

Mercier, V; Luy, D; Hohmann, B W

2003-01-01

During the Paleo Festival in Nyon, Switzerland, which took place from 24th to 29th July 2001, ten volunteers were equipped each evening with small sound level meters which continuously monitored their sound exposure as they circulated among the various festival events. Sound levels at the mixing console and at the place where people are most heavily exposed (in front of the speakers) were measured simultaneously. In addition, a sample of 601 people from the audience were interviewed over the six days of the festival and asked their opinion of sound level and quality, as well as provide details of where in the arena they preferred to listen to the concerts, whether they used ear plugs, if they had experienced any tinnitus, and if so how long it had persisted. The individual sound exposure during a typical evening was on average 95 dB(A) although 8% of the volunteers were exposed to sound levels higher then 100 dB(A). Only 5% of the audience wore ear plugs throughout the concert while 34% used them occasionally. While some 36% of the people interviewed reported that they had experienced tinnitus after listening to loud music, the majority found both the music quality and the sound level good. The sound level limit of 100 dB(A) at the place where the people are most heavily exposed seems to be a good compromise between the public heath issue, the demands of artists and organisers, and the expectations of the public. However, considering the average sound levels to which the public are exposed during a single evening, it is recommended that ear plugs be used by concert-goers who attend more than one day of the festival.

[Acoustical parameters of toys].

PubMed

Harazin, Barbara

2010-01-01

Toys play an important role in the development of the sight and hearing concentration in children. They also support the development of manipulation, gently influence a child and excite its emotional activities. A lot of toys emit various sounds. The aim of the study was to assess sound levels produced by sound-emitting toys used by young children. Acoustical parameters of noise were evaluated for 16 sound-emitting plastic toys in laboratory conditions. The noise level was recorded at four different distances, 10, 20, 25 and 30 cm, from the toy. Measurements of A-weighted sound pressure levels and noise levels in octave band in the frequency range from 31.5 Hz to 16 kHz were performed at each distance. Taking into consideration the highest equivalent A-weighted sound levels produced by tested toys, they can be divided into four groups: below 70 dB (6 toys), from 70 to 74 dB (4 toys), from 75 to 84 dB (3 toys) and from 85 to 94 dB (3 toys). The majority of toys (81%) emitted dominant sound levels in octave band at the frequency range from 2 kHz to 4 kHz. Sound-emitting toys produce the highest acoustic energy at the frequency range of the highest susceptibility of the auditory system. Noise levels produced by some toys can be dangerous to children's hearing.

Loudness-dependent behavioral responses and habituation to sound by the longfin squid (Doryteuthis pealeii).

PubMed

Mooney, T Aran; Samson, Julia E; Schlunk, Andrea D; Zacarias, Samantha

2016-07-01

Sound is an abundant cue in the marine environment, yet we know little regarding the frequency range and levels which induce behavioral responses in ecologically key marine invertebrates. Here we address the range of sounds that elicit unconditioned behavioral responses in squid Doryteuthis pealeii, the types of responses generated, and how responses change over multiple sound exposures. A variety of response types were evoked, from inking and jetting to body pattern changes and fin movements. Squid responded to sounds from 80 to 1000 Hz, with response rates diminishing at the higher and lower ends of this frequency range. Animals responded to the lowest sound levels in the 200-400 Hz range. Inking, an escape response, was confined to the lower frequencies and highest sound levels; jetting was more widespread. Response latencies were variable but typically occurred after 0.36 s (mean) for jetting and 0.14 s for body pattern changes; pattern changes occurred significantly faster. These results demonstrate that squid can exhibit a range of behavioral responses to sound include fleeing, deimatic and protean behaviors, all of which are associated with predator evasion. Response types were frequency and sound level dependent, reflecting a relative loudness concept to sound perception in squid.

The Effect of Looming and Receding Sounds on the Perceived In-Depth Orientation of Depth-Ambiguous Biological Motion Figures

PubMed Central

Schouten, Ben; Troje, Nikolaus F.; Vroomen, Jean; Verfaillie, Karl

2011-01-01

Background The focus in the research on biological motion perception traditionally has been restricted to the visual modality. Recent neurophysiological and behavioural evidence, however, supports the idea that actions are not represented merely visually but rather audiovisually. The goal of the present study was to test whether the perceived in-depth orientation of depth-ambiguous point-light walkers (plws) is affected by the presentation of looming or receding sounds synchronized with the footsteps. Methodology/Principal Findings In Experiment 1 orthographic frontal/back projections of plws were presented either without sound or with sounds of which the intensity level was rising (looming), falling (receding) or stationary. Despite instructions to ignore the sounds and to only report the visually perceived in-depth orientation, plws accompanied with looming sounds were more often judged to be facing the viewer whereas plws paired with receding sounds were more often judged to be facing away from the viewer. To test whether the effects observed in Experiment 1 act at a perceptual level rather than at the decisional level, in Experiment 2 observers perceptually compared orthographic plws without sound or paired with either looming or receding sounds to plws without sound but with perspective cues making them objectively either facing towards or facing away from the viewer. Judging whether either an orthographic plw or a plw with looming (receding) perspective cues is visually most looming becomes harder (easier) when the orthographic plw is paired with looming sounds. Conclusions/Significance The present results suggest that looming and receding sounds alter the judgements of the in-depth orientation of depth-ambiguous point-light walkers. While looming sounds are demonstrated to act at a perceptual level and make plws look more looming, it remains a challenge for future research to clarify at what level in the processing hierarchy receding sounds affect how observers judge the in-depth perception of plws. PMID:21373181

Measurements of humpback whale song sound levels received by a calf in association with a singer.

PubMed

Chen, Jessica; Pack, Adam A; Au, Whitlow W L; Stimpert, Alison K

2016-11-01

Male humpback whales produce loud "songs" on the wintering grounds and some sing while escorting mother-calf pairs, exposing them to near-continuous sounds at close proximity. An Acousonde acoustic and movement recording tag deployed on a calf off Maui, Hawaii captured sounds produced by a singing male escort. Root-mean-square received levels ranged from 126 to 158 dB re 1 μPa. These levels represent rare direct measurements of sound to which a newly born humpback calf may be naturally exposed by a conspecific, and may provide a basis for informed decisions regarding anthropogenic sound levels projected near calves.

Aging Affects Adaptation to Sound-Level Statistics in Human Auditory Cortex.

PubMed

Herrmann, Björn; Maess, Burkhard; Johnsrude, Ingrid S

2018-02-21

Optimal perception requires efficient and adaptive neural processing of sensory input. Neurons in nonhuman mammals adapt to the statistical properties of acoustic feature distributions such that they become sensitive to sounds that are most likely to occur in the environment. However, whether human auditory responses adapt to stimulus statistical distributions and how aging affects adaptation to stimulus statistics is unknown. We used MEG to study how exposure to different distributions of sound levels affects adaptation in auditory cortex of younger (mean: 25 years; n = 19) and older (mean: 64 years; n = 20) adults (male and female). Participants passively listened to two sound-level distributions with different modes (either 15 or 45 dB sensation level). In a control block with long interstimulus intervals, allowing neural populations to recover from adaptation, neural response magnitudes were similar between younger and older adults. Critically, both age groups demonstrated adaptation to sound-level stimulus statistics, but adaptation was altered for older compared with younger people: in the older group, neural responses continued to be sensitive to sound level under conditions in which responses were fully adapted in the younger group. The lack of full adaptation to the statistics of the sensory environment may be a physiological mechanism underlying the known difficulty that older adults have with filtering out irrelevant sensory information. SIGNIFICANCE STATEMENT Behavior requires efficient processing of acoustic stimulation. Animal work suggests that neurons accomplish efficient processing by adjusting their response sensitivity depending on statistical properties of the acoustic environment. Little is known about the extent to which this adaptation to stimulus statistics generalizes to humans, particularly to older humans. We used MEG to investigate how aging influences adaptation to sound-level statistics. Listeners were presented with sounds drawn from sound-level distributions with different modes (15 vs 45 dB). Auditory cortex neurons adapted to sound-level statistics in younger and older adults, but adaptation was incomplete in older people. The data suggest that the aging auditory system does not fully capitalize on the statistics available in sound environments to tune the perceptual system dynamically. Copyright © 2018 the authors 0270-6474/18/381989-11$15.00/0.

Transfer of knowledge from sound quality measurement to noise impact evaluation

NASA Astrophysics Data System (ADS)

Genuit, Klaus

2004-05-01

It is well known that the measurement and analysis of sound quality requires a complex procedure with consideration of the physical, psychoacoustical and psychological aspects of sound. Sound quality cannot be described only by a simple value based on A-weighted sound pressure level measurements. The A-weighted sound pressure level is sufficient to predict the probabilty that the human ear could be damaged by sound but the A-weighted level is not the correct descriptor for the annoyance of a complex sound situation given by several different sound events at different and especially moving positions (soundscape). On the one side, the consideration of the spectral distribution and the temporal pattern (psychoacoustics) is requested and, on the other side, the subjective attitude with respect to the sound situation, the expectation and experience of the people (psychology) have to be included in context with the complete noise impact evaluation. This paper describes applications of the newest methods of sound quality measurements-as it is well introduced at the car manufacturers-based on artifical head recordings and signal processing comparable to the human hearing used in noisy environments like community/traffic noise.

The hearing threshold of a harbor porpoise (Phocoena phocoena) for impulsive sounds (L).

PubMed

Kastelein, Ronald A; Gransier, Robin; Hoek, Lean; de Jong, Christ A F

2012-08-01

The distance at which harbor porpoises can hear underwater detonation sounds is unknown, but depends, among other factors, on the hearing threshold of the species for impulsive sounds. Therefore, the underwater hearing threshold of a young harbor porpoise for an impulsive sound, designed to mimic a detonation pulse, was quantified by using a psychophysical technique. The synthetic exponential pulse with a 5 ms time constant was produced and transmitted by an underwater projector in a pool. The resulting underwater sound, though modified by the response of the projection system and by the pool, exhibited the characteristic features of detonation sounds: A zero to peak sound pressure level of at least 30 dB (re 1 s(-1)) higher than the sound exposure level, and a short duration (34 ms). The animal's 50% detection threshold for this impulsive sound occurred at a received unweighted broadband sound exposure level of 60 dB re 1 μPa(2)s. It is shown that the porpoise's audiogram for short-duration tonal signals [Kastelein et al., J. Acoust. Soc. Am. 128, 3211-3222 (2010)] can be used to estimate its hearing threshold for impulsive sounds.

Threshold for onset of injury in Chinook salmon from exposure to impulsive pile driving sounds.

PubMed

Halvorsen, Michele B; Casper, Brandon M; Woodley, Christa M; Carlson, Thomas J; Popper, Arthur N

2012-01-01

The risk of effects to fishes and other aquatic life from impulsive sound produced by activities such as pile driving and seismic exploration is increasing throughout the world, particularly with the increased exploitation of oceans for energy production. At the same time, there are few data that provide insight into the effects of these sounds on fishes. The goal of this study was to provide quantitative data to define the levels of impulsive sound that could result in the onset of barotrauma to fish. A High Intensity Controlled Impedance Fluid filled wave Tube was developed that enabled laboratory simulation of high-energy impulsive sound that were characteristic of aquatic far-field, plane-wave acoustic conditions. The sounds used were based upon the impulsive sounds generated by an impact hammer striking a steel shell pile. Neutrally buoyant juvenile Chinook salmon (Oncorhynchus tshawytscha) were exposed to impulsive sounds and subsequently evaluated for barotrauma injuries. Observed injuries ranged from mild hematomas at the lowest sound exposure levels to organ hemorrhage at the highest sound exposure levels. Frequency of observed injuries were used to compute a biological response weighted index (RWI) to evaluate the physiological impact of injuries at the different exposure levels. As single strike and cumulative sound exposure levels (SEL(ss), SEL(cum) respectively) increased, RWI values increased. Based on the results, tissue damage associated with adverse physiological costs occurred when the RWI was greater than 2. In terms of sound exposure levels a RWI of 2 was achieved for 1920 strikes by 177 dB re 1 µPa(2)⋅s SEL(ss) yielding a SEL(cum) of 210 dB re 1 µPa(2)⋅s, and for 960 strikes by 180 dB re 1 µPa(2)⋅s SEL(ss) yielding a SEL(cum) of 210 dB re 1 µPa(2)⋅s. These metrics define thresholds for onset of injury in juvenile Chinook salmon.

Threshold for Onset of Injury in Chinook Salmon from Exposure to Impulsive Pile Driving Sounds

PubMed Central

Halvorsen, Michele B.; Casper, Brandon M.; Woodley, Christa M.; Carlson, Thomas J.; Popper, Arthur N.

2012-01-01

The risk of effects to fishes and other aquatic life from impulsive sound produced by activities such as pile driving and seismic exploration is increasing throughout the world, particularly with the increased exploitation of oceans for energy production. At the same time, there are few data that provide insight into the effects of these sounds on fishes. The goal of this study was to provide quantitative data to define the levels of impulsive sound that could result in the onset of barotrauma to fish. A High Intensity Controlled Impedance Fluid filled wave Tube was developed that enabled laboratory simulation of high-energy impulsive sound that were characteristic of aquatic far-field, plane-wave acoustic conditions. The sounds used were based upon the impulsive sounds generated by an impact hammer striking a steel shell pile. Neutrally buoyant juvenile Chinook salmon (Oncorhynchus tshawytscha) were exposed to impulsive sounds and subsequently evaluated for barotrauma injuries. Observed injuries ranged from mild hematomas at the lowest sound exposure levels to organ hemorrhage at the highest sound exposure levels. Frequency of observed injuries were used to compute a biological response weighted index (RWI) to evaluate the physiological impact of injuries at the different exposure levels. As single strike and cumulative sound exposure levels (SELss, SELcum respectively) increased, RWI values increased. Based on the results, tissue damage associated with adverse physiological costs occurred when the RWI was greater than 2. In terms of sound exposure levels a RWI of 2 was achieved for 1920 strikes by 177 dB re 1 µPa2⋅s SELss yielding a SELcum of 210 dB re 1 µPa2⋅s, and for 960 strikes by 180 dB re 1 µPa2⋅s SELss yielding a SELcum of 210 dB re 1 µPa2⋅s. These metrics define thresholds for onset of injury in juvenile Chinook salmon. PMID:22745695

Statistical Analysis for Subjective and Objective Evaluations of Dental Drill Sounds.

PubMed

Yamada, Tomomi; Kuwano, Sonoko; Ebisu, Shigeyuki; Hayashi, Mikako

2016-01-01

The sound produced by a dental air turbine handpiece (dental drill) can markedly influence the sound environment in a dental clinic. Indeed, many patients report that the sound of a dental drill elicits an unpleasant feeling. Although several manufacturers have attempted to reduce the sound pressure levels produced by dental drills during idling based on ISO 14457, the sound emitted by such drills under active drilling conditions may negatively influence the dental clinic sound environment. The physical metrics related to the unpleasant impressions associated with dental drill sounds have not been determined. In the present study, psychological measurements of dental drill sounds were conducted with the aim of facilitating improvement of the sound environment at dental clinics. Specifically, we examined the impressions elicited by the sounds of 12 types of dental drills in idling and drilling conditions using a semantic differential. The analysis revealed that the impressions of dental drill sounds varied considerably between idling and drilling conditions and among the examined drills. This finding suggests that measuring the sound of a dental drill in idling conditions alone may be insufficient for evaluating the effects of the sound. We related the results of the psychological evaluations to those of measurements of the physical metrics of equivalent continuous A-weighted sound pressure levels (LAeq) and sharpness. Factor analysis indicated that impressions of the dental drill sounds consisted of two factors: "metallic and unpleasant" and "powerful". LAeq had a strong relationship with "powerful impression", calculated sharpness was positively related to "metallic impression", and "unpleasant impression" was predicted by the combination of both LAeq and calculated sharpness. The present analyses indicate that, in addition to a reduction in sound pressure level, refining the frequency components of dental drill sounds is important for creating a comfortable sound environment in dental clinics.

Confinement of gigahertz sound and light in Tamm plasmon resonators

NASA Astrophysics Data System (ADS)

Villafañe, V.; Bruchhausen, A. E.; Jusserand, B.; Senellart, P.; Lemaître, A.; Fainstein, A.

2015-10-01

We demonstrate theoretically and by pump-probe picosecond acoustics experiments the simultaneous confinement of light and gigahertz sound in Tamm plasmon resonators, formed by depositing a thin layer of Au onto a GaAs/AlGaAs Bragg reflector. The cavity has InGaAs quantum dots (QDs) embedded at the maximum of the confined optical field in the first GaAs layer. The different sound generation and detection mechanisms are theoretically analyzed. It is shown that the Au layer absorption and the resonant excitation of the QDs are the more efficient light-sound transducers for the coupling of near-infrared light with the confined acoustic modes, while the displacement of the interfaces is the main back-action mechanism at these energies. The prospects for the compact realization of optomechanical resonators based on Tamm plasmon cavities are discussed.

14 CFR 36.6 - Incorporation by reference.

Code of Federal Regulations, 2010 CFR

2010-01-01

... No. 179, entitled “Precision Sound Level Meters,” dated 1973. (ii) IEC Publication No. 225, entitled... 1966. (iii) IEC Publication No. 651, entitled “Sound Level Meters,” first edition, dated 1979. (iv) IEC... edition, dated 1976. (v) IEC Publication No. 804, entitled “Integrating-averaging Sound Level Meters...

49 CFR 210.25 - Measurement criteria and procedures.

Code of Federal Regulations, 2011 CFR

2011-10-01

... American National Standard Institute Standards, “Method for Measurement of Sound Pressure Levels,” (ANSI S1... measurement indicating a violation. (ii) The sound level measurement system shall be checked not less than... calibrator of the microphone coupler type designed for the sound level measurement system in use shall be...

49 CFR 325.25 - Calibration of measurement systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Standard Institute Standard Methods for Measurements of Sound Pressure Levels (ANSI S1.13-1971) for field... sound level measurement system must be calibrated and appropriately adjusted at one or more frequencies... 5-15 minutes thereafter, until it has been determined that the sound level measurement system has...

49 CFR 325.25 - Calibration of measurement systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Standard Institute Standard Methods for Measurements of Sound Pressure Levels (ANSI S1.13-1971) for field... sound level measurement system must be calibrated and appropriately adjusted at one or more frequencies... 5-15 minutes thereafter, until it has been determined that the sound level measurement system has...

49 CFR 325.39 - Measurement procedure; highway operations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... shall be made of the sound level generated by a motor vehicle operating through the measurement area on..., acceleration or deceleration. (b) The sound level generated by the motor vehicle is the highest reading observed on the sound level measurement system as the vehicle passes through the measurement area...

49 CFR 325.39 - Measurement procedure; highway operations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... shall be made of the sound level generated by a motor vehicle operating through the measurement area on..., acceleration or deceleration. (b) The sound level generated by the motor vehicle is the highest reading observed on the sound level measurement system as the vehicle passes through the measurement area...

24 CFR 51.103 - Criteria and standards.

Code of Federal Regulations, 2011 CFR

2011-04-01

...-night average sound level produced as the result of the accumulation of noise from all sources contributing to the external noise environment at the site. Day-night average sound level, abbreviated as DNL and symbolized as Ldn, is the 24-hour average sound level, in decibels, obtained after addition of 10...

Calculating far-field radiated sound pressure levels from NASTRAN output

NASA Technical Reports Server (NTRS)

Lipman, R. R.

1986-01-01

FAFRAP is a computer program which calculates far field radiated sound pressure levels from quantities computed by a NASTRAN direct frequency response analysis of an arbitrarily shaped structure. Fluid loading on the structure can be computed directly by NASTRAN or an added-mass approximation to fluid loading on the structure can be used. Output from FAFRAP includes tables of radiated sound pressure levels and several types of graphic output. FAFRAP results for monopole and dipole sources compare closely with an explicit calculation of the radiated sound pressure level for those sources.

Convective Lofting Links Indian Ocean Air Pollution to Paradoxical South Atlantic Ozone Maxima

NASA Technical Reports Server (NTRS)

Chatfield, Robert B.; Guan, Hong; Thompson, Anne M.; Witte, Jacquelyn C.

2003-01-01

We describe a broad resolution of the "Atlantic Paradox" concerning the seasonal and geographic distribution of tropical tropospheric ozone. We describe periods of significant maximum tropospheric O3 for Jan.-April, 1999, exploiting satellite estimates and SHADOZ (Southern Hemisphere Additional Ozonesondes). Trajectory analyses connecting sondes and Total Tropospheric Ozone (TTO)O3 maps suggest a complex influence from the Indian Ocean: beginning with mixed combustion sources, then low level transport, cumulonimbus venting, and finally high-level transport to the west, with possible mixing over Africa. For the Jan.- March highest column-O3 periods in the Atlantic, distinct sounding peaks trace to specific NO sources, especially lightning, while in the same episodes, recurring every 30 or 60 days, more diffuse buildups of Indian-to-Atlantic pollution make important contributions.

Convective lofting links Indian Ocean air pollution to paradoxical South Atlantic ozone maxima

NASA Technical Reports Server (NTRS)

Chatfield, R. B.; Guan, H.; Thompson, A. M.; Witte, J. C.

2005-01-01

We describe a broad resolution of the Atlantic Parado concerning the seasonal and geographic distribution, of tropical tropospheric ozone. We highlight periods of significant maximum tropospheric O3 for Jan.- April, 1999, exploiting satellite estimates and SHADOZ (Southern Hemisphere Additional Ozonesondes). Trajectory analyses connecting sondes and Total Tropospheric Ozone (TTO) maps suggest a complex influence from the Indian Ocean: beginning with mixed combustion sources, then low level transport, cumulonimbus venting, possible stratospheric input, and finally high-level transport to the west, with possible mixing over Africa. For the Jan.-March highest column-O3 periods in the Atlantic, distinct sounding peaks trace to specific NO sources, especially lightning, while in the same episodes, recurring every 20-50 days, more diffuse buildups of Indian-to-Atlantic pollution make important contributions.

Experiment on Finite Amplitude Sound Propagation in a Fluid with a Strong Sound Speed Gradient

NASA Astrophysics Data System (ADS)

Hobæk, H.; Voll, A.˚.; Fardal, R.; Calise, L.

2006-05-01

A closed tank of dimensions 0.5 × 0.5 × 2.7 m3, filled with a mixture of ethanol and water to produce an almost linear sound speed profile with a gradient near 450 (m/s)/m, served the purpose for investigating shocked sound wave propagation in a stratified environment. As the sound speed profile evolved by diffusion a number of different measurements were taken, both in areas with caustics, shadow zones, along the main beam and along the bottom. After about one year, part of the fluid was re-mixed to obtain a pronounced sound speed maximum some 20 cm above the bottom. The high intensity sound was produced by a plane circular piston type sound source with near-field length 45 cm and half power angle 0.8° at 1.1 MHz, placed near one end of the tank. Its tilt angle and depth could be varied. A 0.5 mm diameter PVDF needle hydrophone (Precision Acoustics) mapped the sound field in a vertical slice in the range 0.9 - 2.4 m, remotely controlled by a PC. We present results from measurements in a shadow zone and along the bottom. The latter, in particular, displays unexpected amplitude variations. The project was funded by the European Commission, contract number G4RD-CT-2000-00398.

24 CFR Appendix I to Subpart B of... - Definition of Acoustical Quantities

Code of Federal Regulations, 2010 CFR

2010-04-01

... micropascals. Day-night average sound level, abbreviated as DNL, and symbolized mathematically as Ldn is... day-night average sound level produced by the loud impulsive sounds shall have 8 decibels added to it...

The acoustic performance of double-skin facades: A design support tool for architects

NASA Astrophysics Data System (ADS)

Batungbakal, Aireen

This study assesses and validates the influence of measuring sound in the urban environment and the influence of glass facade components in reducing sound transmission to the indoor environment. Among the most reported issues affecting workspaces, increased awareness to minimize noise led building designers to reconsider the design of building envelopes and its site environment. Outdoor sound conditions, such as traffic noise, challenge designers to accurately estimate the capability of glass facades in acquiring an appropriate indoor sound quality. Indicating the density of the urban environment, field-tests acquired existing sound levels in areas of high commercial development, employment, and traffic activity, establishing a baseline for sound levels common in urban work areas. Composed from the direct sound transmission loss of glass facades simulated through INSUL, a sound insulation software, data is utilized as an informative tool correlating the response of glass facade components towards existing outdoor sound levels of a project site in order to achieve desired indoor sound levels. This study progresses to link the disconnection in validating the acoustic performance of glass facades early in a project's design, from conditioned settings such as field-testing and simulations to project completion. Results obtained from the study's facade simulations and facade comparison supports that acoustic comfort is not limited to a singular solution, but multiple design options responsive to its environment.

Reinvestigation of the relationship between the amplitude of the first heart sound to cardiac dynamics.

PubMed

Tang, Hong; Ruan, Chengjie; Qiu, Tianshuang; Park, Yongwan; Xiao, Shouzhong

2013-08-01

The relationships between the amplitude of the first heart sound (S1) and the rising rate of left ventricular pressure (LVP) concluded in previous studies were not consistent. Some researchers believed the relationship was positively linear; others stated the relationship was only positively correlated. To further investigate this relationship, this study simultaneously sampled the external phonocardiogram, electrocardiogram, and intracardiac pressure in the left ventricle in three anesthetized dogs, while invoking wide hemodynamic changes using various doses of epinephrine. The relationship between the maximum amplitude of S1 and the maximum rising rate of LVP and the relationship between the amplitude of dominant peaks/valleys and the corresponding rising rate of LVP were examined by linear, quadratic, cubic, and exponential models. The results showed that the relationships are best fit by nonlinear exponential models.

The maximum intelligible range of the human voice

NASA Astrophysics Data System (ADS)

Boren, Braxton

This dissertation examines the acoustics of the spoken voice at high levels and the maximum number of people that could hear such a voice unamplified in the open air. In particular, it examines an early auditory experiment by Benjamin Franklin which sought to determine the maximum intelligible crowd for the Anglican preacher George Whitefield in the eighteenth century. Using Franklin's description of the experiment and a noise source on Front Street, the geometry and diffraction effects of such a noise source are examined to more precisely pinpoint Franklin's position when Whitefield's voice ceased to be intelligible. Based on historical maps, drawings, and prints, the geometry and material of Market Street is constructed as a computer model which is then used to construct an acoustic cone tracing model. Based on minimal values of the Speech Transmission Index (STI) at Franklin's position, Whitefield's on-axis Sound Pressure Level (SPL) at 1 m is determined, leading to estimates centering around 90 dBA. Recordings are carried out on trained actors and singers to determine their maximum time-averaged SPL at 1 m. This suggests that the greatest average SPL achievable by the human voice is 90-91 dBA, similar to the median estimates for Whitefield's voice. The sites of Whitefield's largest crowds are acoustically modeled based on historical evidence and maps. Based on Whitefield's SPL, the minimal STI value, and the crowd's background noise, this allows a prediction of the minimally intelligible area for each site. These yield maximum crowd estimates of 50,000 under ideal conditions, while crowds of 20,000 to 30,000 seem more reasonable when the crowd was reasonably quiet and Whitefield's voice was near 90 dBA.

Brief report: sound output of infant humidifiers.

PubMed

Royer, Allison K; Wilson, Paul F; Royer, Mark C; Miyamoto, Richard T

2015-06-01

The sound pressure levels (SPLs) of common infant humidifiers were determined to identify the likely sound exposure to infants and young children. This primary investigative research study was completed at a tertiary-level academic medical center otolaryngology and audiology laboratory. Five commercially available humidifiers were obtained from brick-and-mortar infant supply stores. Sound levels were measured at 20-, 100-, and 150-cm distances at all available humidifier settings. Two of 5 (40%) humidifiers tested had SPL readings greater than the recommended hospital infant nursery levels (50 dB) at distances up to 100 cm. In this preliminary study, it was demonstrated that humidifiers marketed for infant nurseries may produce appreciably high decibel levels. Further characterization of the effect of humidifier design on SPLs and further elucidation of ambient sound levels associated with hearing risk are necessary before definitive conclusions and recommendations can be made. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.

X-1 research aircraft landing on lakebed

NASA Technical Reports Server (NTRS)

1947-01-01

The first of the rocket-powered research aircraft, the X-1 (originally designated the XS-1), was a bullet-shaped airplane that was built by the Bell Aircraft Company for the US Air Force and the National Advisory Committee on Aeronautics (NACA). The mission of the X-1 was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier'. The first of the three X-1s was glide-tested at Pinecastle Air Force Base, FL, in early 1946. The first powered flight of the X-1 was made on Dec. 9, 1946, at Edwards Air Force Base with Chalmers Goodlin, a Bell test pilot, at the controls. On Oct. 14, 1947, with USAF Captain Charles 'Chuck' Yeager as pilot, the aircraft flew faster than the speed of sound for the first time. Captain Yeager ignited the four-chambered XLR-11 rocket engines after being air-launched from under the bomb bay of a B-29 at 21,000 ft. The 6,000-lbthrust ethyl alcohol/liquid oxygen burning rockets, built by Reaction Motors, Inc., pushed him up to a speed of 700 mph in level flight. Captain Yeager was also the pilot when the X-1 reached its maximum speed of 957 mph. Another USAF pilot. Lt. Col. Frank Everest, Jr., was credited with taking the X-1 to its maximum altitude of 71,902 ft. Eighteen pilots in all flew the X-1s. The number three plane was destroyed in a fire before ever making any powered flights. A single-place monoplane, the X-1 was 31 ft long, 10 ft high, and had a wingspan of 29 ft. It weighed 4,900 lb and carried 8,200 lb of fuel. It had a flush cockpit with a side entrance and no ejection seat. This roughly 30-second video clip shows the X-1 landing on Rogers Dry Lakebed followed by the safety chase aircraft.

The rotary subwoofer: a controllable infrasound source.

PubMed

Park, Joseph; Garcés, Milton; Thigpen, Bruce

2009-04-01

The rotary subwoofer is a novel acoustic transducer capable of projecting infrasonic signals at high sound pressure levels. The projector produces higher acoustic particle velocities than conventional transducers which translate into higher radiated sound pressure levels. This paper characterizes measured performance of a rotary subwoofer and presents a model to predict sound pressure levels.

Recording and Analysis of Bowel Sounds.

PubMed

Zaborski, Daniel; Halczak, Miroslaw; Grzesiak, Wilhelm; Modrzejewski, Andrzej

2015-01-01

The aim of this study was to construct an electronic bowel sound recording system and determine its usefulness for the diagnosis of appendicitis, mechanical ileus and diffuse peritonitis. A group of 67 subjects aged 17 to 88 years including 15 controls was examined. Bowel sounds were recorded using an electret microphone placed on the right side of the hypogastrium and connected to a laptop computer. The method of adjustable grids (converted into binary matrices) was used for bowel sounds analysis. Significantly, fewer (p ≤ 0.05) sounds were found in the mechanical ileus (1004.4) and diffuse peritonitis (466.3) groups than in the controls (2179.3). After superimposing adjustable binary matrices on combined sounds (interval between sounds <0.01 s), significant relationships (p ≤ 0.05) were found between particular positions in the matrices (row-column) and the patient groups. These included the A1_T1 and A1_T2 positions and mechanical ileus as well as the A1_T2 and A1_T4 positions and appendicitis. For diffuse peritonitis, significant positions were A5_T4 and A1_T4. Differences were noted in the number of sounds and binary matrices in the groups of patients with acute abdominal diseases. Certain features of bowel sounds characteristic of individual abdominal diseases were indicated. BS: bowel sound; APP: appendicitis; IL: mechanical ileus; PE: diffuse peritonitis; CG: control group; NSI: number of sound impulses; NCI: number of combined sound impulses; MBS: mean bit-similarity; TMIN: minimum time between impulses; TMAX: maximum time between impulses; TMEAN: mean time between impulses. Zaborski D, Halczak M, Grzesiak W, Modrzejewski A. Recording and Analysis of Bowel Sounds. Euroasian J Hepato-Gastroenterol 2015;5(2):67-73.

EEG oscillations entrain their phase to high-level features of speech sound.

PubMed

Zoefel, Benedikt; VanRullen, Rufin

2016-01-01

Phase entrainment of neural oscillations, the brain's adjustment to rhythmic stimulation, is a central component in recent theories of speech comprehension: the alignment between brain oscillations and speech sound improves speech intelligibility. However, phase entrainment to everyday speech sound could also be explained by oscillations passively following the low-level periodicities (e.g., in sound amplitude and spectral content) of auditory stimulation-and not by an adjustment to the speech rhythm per se. Recently, using novel speech/noise mixture stimuli, we have shown that behavioral performance can entrain to speech sound even when high-level features (including phonetic information) are not accompanied by fluctuations in sound amplitude and spectral content. In the present study, we report that neural phase entrainment might underlie our behavioral findings. We observed phase-locking between electroencephalogram (EEG) and speech sound in response not only to original (unprocessed) speech but also to our constructed "high-level" speech/noise mixture stimuli. Phase entrainment to original speech and speech/noise sound did not differ in the degree of entrainment, but rather in the actual phase difference between EEG signal and sound. Phase entrainment was not abolished when speech/noise stimuli were presented in reverse (which disrupts semantic processing), indicating that acoustic (rather than linguistic) high-level features play a major role in the observed neural entrainment. Our results provide further evidence for phase entrainment as a potential mechanism underlying speech processing and segmentation, and for the involvement of high-level processes in the adjustment to the rhythm of speech. Copyright © 2015 Elsevier Inc. All rights reserved.

Computerised respiratory sounds can differentiate smokers and non-smokers.

PubMed

Oliveira, Ana; Sen, Ipek; Kahya, Yasemin P; Afreixo, Vera; Marques, Alda

2017-06-01

Cigarette smoking is often associated with the development of several respiratory diseases however, if diagnosed early, the changes in the lung tissue caused by smoking may be reversible. Computerised respiratory sounds have shown to be sensitive to detect changes within the lung tissue before any other measure, however it is unknown if it is able to detect changes in the lungs of healthy smokers. This study investigated the differences between computerised respiratory sounds of healthy smokers and non-smokers. Healthy smokers and non-smokers were recruited from a university campus. Respiratory sounds were recorded simultaneously at 6 chest locations (right and left anterior, lateral and posterior) using air-coupled electret microphones. Airflow (1.0-1.5 l/s) was recorded with a pneumotachograph. Breathing phases were detected using airflow signals and respiratory sounds with validated algorithms. Forty-four participants were enrolled: 18 smokers (mean age 26.2, SD = 7 years; mean FEV 1 % predicted 104.7, SD = 9) and 26 non-smokers (mean age 25.9, SD = 3.7 years; mean FEV 1 % predicted 96.8, SD = 20.2). Smokers presented significantly higher frequency at maximum sound intensity during inspiration [(M = 117, SD = 16.2 Hz vs. M = 106.4, SD = 21.6 Hz; t(43) = -2.62, p = 0.0081, d z  = 0.55)], lower expiratory sound intensities (maximum intensity: [(M = 48.2, SD = 3.8 dB vs. M = 50.9, SD = 3.2 dB; t(43) = 2.68, p = 0.001, d z  = -0.78)]; mean intensity: [(M = 31.2, SD = 3.6 dB vs. M = 33.7,SD = 3 dB; t(43) = 2.42, p = 0.001, d z  = 0.75)] and higher number of inspiratory crackles (median [interquartile range] 2.2 [1.7-3.7] vs. 1.5 [1.2-2.2], p = 0.081, U = 110, r = -0.41) than non-smokers. Significant differences between computerised respiratory sounds of smokers and non-smokers have been found. Changes in respiratory sounds are often the earliest sign of disease. Thus, computerised respiratory sounds might be a promising measure to early detect smoking related respiratory diseases.

Decadal trends in Indian Ocean ambient sound.

PubMed

Miksis-Olds, Jennifer L; Bradley, David L; Niu, Xiaoyue Maggie

2013-11-01

The increase of ocean noise documented in the North Pacific has sparked concern on whether the observed increases are a global or regional phenomenon. This work provides evidence of low frequency sound increases in the Indian Ocean. A decade (2002-2012) of recordings made off the island of Diego Garcia, UK in the Indian Ocean was parsed into time series according to frequency band and sound level. Quarterly sound level comparisons between the first and last years were also performed. The combination of time series and temporal comparison analyses over multiple measurement parameters produced results beyond those obtainable from a single parameter analysis. The ocean sound floor has increased over the past decade in the Indian Ocean. Increases were most prominent in recordings made south of Diego Garcia in the 85-105 Hz band. The highest sound level trends differed between the two sides of the island; the highest sound levels decreased in the north and increased in the south. Rate, direction, and magnitude of changes among the multiple parameters supported interpretation of source functions driving the trends. The observed sound floor increases are consistent with concurrent increases in shipping, wind speed, wave height, and blue whale abundance in the Indian Ocean.

Decreasing sound and vibration during ground transport of infants with very low birth weight.

PubMed

Prehn, J; McEwen, I; Jeffries, L; Jones, M; Daniels, T; Goshorn, E; Marx, C

2015-02-01

To measure the effectiveness of modifications to reduce sound and vibration during interhospital ground transport of a simulated infant with very low birth weight (VLBW) and a gestational age of 30 weeks, a period of high susceptibility to germinal matrix and intraventricular hemorrhage. Researchers measured vibration and sound levels during infant transport, and compared levels after modifications to the transport incubator mattresses, addition of vibration isolators under incubator wheels, addition of mass to the incubator mattress and addition of incubator acoustic cover. Modifications did not decrease sound levels inside the transport incubator during transport. The combination of a gel mattress over an air chambered mattress was effective in decreasing vibration levels for the 1368 g simulated infant. Transport mattress effectiveness in decreasing vibration is influenced by infant weight. Modifications that decrease vibration for infants weighing 2000 g are not effective for infants with VLBW. Sound levels are not affected by incubator covers, suggesting that sound is transmitted into the incubator as a low-frequency vibration through the incubator's contact with the ambulance. Medical transportation can apply industrial methods of vibration and sound control to protect infants with VLBW from excessive physical strain of transport during vulnerable periods of development.

Noise Levels in Patient Rooms and at Nursing Stations at Three VA Medical Centers.

PubMed

Hill, Jennifer N; LaVela, Sherri L

2015-01-01

To conduct an assessment of sound, dB(A) levels, in two areas of the hospital: patient rooms and nurse stations using sound meters (SMs). The World Health Organization (WHO) recommends sound levels of 35 dB(A) during the day and 30 dB(A) during the night; however, many hospitals exceed these recommended levels. Assessing post-occupancy sound levels enables hospital administrators and healthcare workers to identify whether interventions to improve sound levels are needed. Sound assessments were conducted at three healthcare facilities in both patient rooms and nursing stations, and we include information on facility characteristics. An Amprobe SM-20A Sound Level Meter was placed for a 24-hr period and recorded decibel levels every 8 min. These sound levels were averaged for each hour for reporting purposes. Averages as well as highest and lowest readings are reported for both daytime (8 a.m.-10 p.m.) and nighttime (10 p.m.-8 a.m.) for each facility. All three sites are considered urban and are classified with the highest complexity level (1a). Average daytime measurements for patient rooms and their corresponding nurses stations were as follows: Site A-63 dB(A)/56 dB(A), Site B-52 dB(A)/55 dB(A), and Site C-42 dB(A)/59 dB(A). Average nighttime measurements for patient rooms and nurses stations were Site A-62 dB(A)/55 dB(A), Site B-48 dB(A)/55 dB(A), and Site C-42 dB(A)/60 dB(A). Our findings, considered independently and collectively, showed that facilities in this study exceeded the WHO-recommended sound levels for patient rooms of 35 dB(A) during daytime and 30 dB(A) during nighttime. Research has reported negative patient outcomes, for example, decreased satisfaction, sleep disturbance, and higher incidence of rehospitalization in patients staying in areas with higher noise levels. © The Author(s) 2015.

Tutorial and Guidelines on Measurement of Sound Pressure Level in Voice and Speech.

PubMed

Švec, Jan G; Granqvist, Svante

2018-03-15

Sound pressure level (SPL) measurement of voice and speech is often considered a trivial matter, but the measured levels are often reported incorrectly or incompletely, making them difficult to compare among various studies. This article aims at explaining the fundamental principles behind these measurements and providing guidelines to improve their accuracy and reproducibility. Basic information is put together from standards, technical, voice and speech literature, and practical experience of the authors and is explained for nontechnical readers. Variation of SPL with distance, sound level meters and their accuracy, frequency and time weightings, and background noise topics are reviewed. Several calibration procedures for SPL measurements are described for stand-mounted and head-mounted microphones. SPL of voice and speech should be reported together with the mouth-to-microphone distance so that the levels can be related to vocal power. Sound level measurement settings (i.e., frequency weighting and time weighting/averaging) should always be specified. Classified sound level meters should be used to assure measurement accuracy. Head-mounted microphones placed at the proximity of the mouth improve signal-to-noise ratio and can be taken advantage of for voice SPL measurements when calibrated. Background noise levels should be reported besides the sound levels of voice and speech.

Amplitude modulation of sound from wind turbines under various meteorological conditions.

PubMed

Larsson, Conny; Öhlund, Olof

2014-01-01

Wind turbine (WT) sound annoys some people even though the sound levels are relatively low. This could be because of the amplitude modulated "swishing" characteristic of the turbine sound, which is not taken into account by standard procedures for measuring average sound levels. Studies of sound immission from WTs were conducted continually between 19 August 2011 and 19 August 2012 at two sites in Sweden. A method for quantifying the degree and strength of amplitude modulation (AM) is introduced here. The method reveals that AM at the immission points occur under specific meteorological conditions. For WT sound immission, the wind direction and sound speed gradient are crucial for the occurrence of AM. Interference between two or more WTs could probably enhance AM. The mechanisms by which WT sound is amplitude modulated are not fully understood.

Relations among pure-tone sound stimuli, neural activity, and the loudness sensation

NASA Technical Reports Server (NTRS)

Howes, W. L.

1972-01-01

Both the physiological and psychological responses to pure-tone sound stimuli are used to derive formulas which: (1) relate the loudness, loudness level, and sound-pressure level of pure tones; (2) apply continuously over most of the acoustic regime, including the loudness threshold; and (3) contain no undetermined coefficients. Some of the formulas are fundamental for calculating the loudness of any sound. Power-law formulas relating the pure-tone sound stimulus, neural activity, and loudness are derived from published data.

The limits of applicability of the sound exposure level (SEL) metric to temporal threshold shifts (TTS) in beluga whales, Delphinapterus leucas.

PubMed

Popov, Vladimir V; Supin, Alexander Ya; Rozhnov, Viatcheslav V; Nechaev, Dmitry I; Sysueva, Evgenia V

2014-05-15

The influence of fatiguing sound level and duration on post-exposure temporary threshold shift (TTS) was investigated in two beluga whales (Delphinapterus leucas). The fatiguing sound was half-octave noise with a center frequency of 22.5 kHz. TTS was measured at a test frequency of 32 kHz. Thresholds were measured by recording rhythmic evoked potentials (the envelope following response) to a test series of short (eight cycles) tone pips with a pip rate of 1000 s(-1). TTS increased approximately proportionally to the dB measure of both sound pressure (sound pressure level, SPL) and duration of the fatiguing noise, as a product of these two variables. In particular, when the noise parameters varied in a manner that maintained the product of squared sound pressure and time (sound exposure level, SEL, which is equivalent to the overall noise energy) at a constant level, TTS was not constant. Keeping SEL constant, the highest TTS appeared at an intermediate ratio of SPL to sound duration and decreased at both higher and lower ratios. Multiplication (SPL multiplied by log duration) better described the experimental data than an equal-energy (equal SEL) model. The use of SEL as a sole universal metric may result in an implausible assessment of the impact of a fatiguing sound on hearing thresholds in odontocetes, including under-evaluation of potential risks. © 2014. Published by The Company of Biologists Ltd.

Contaminant loading to Puget Sound from two marinas. Puget Sound estuary program. Final report, June 1988-October 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crecelius, E.A.; Fortman, T.J.; Kiesser, S.L.

1989-07-01

Concentrations of Cu, Pb, Zn, PAH's, TBT and FC bacteria were measured in surface sediment, sediment-trap, and water-column samples at two marinas in Puget Sound during summer of 1988. Levels of contaminants inside the marinas were compared with levels outside. TBT had greatest elevation in marina sediments compared to reference sediments. Few of sediments exceeded Puget Sound AET sediment quality values but most did exceed PSDDA screening levels for in-water disposal of dredged sediment. All marinas estimated to contribute less than one percent of total mass loading of Cu, Pb and Zn to main basin of Puget Sound. Contribution ofmore » TBT may be much more significant if antifouling paints are the major source for Puget Sound.« less

Rotorcraft Noise Model

NASA Technical Reports Server (NTRS)

Lucas, Michael J.; Marcolini, Michael A.

1997-01-01

The Rotorcraft Noise Model (RNM) is an aircraft noise impact modeling computer program being developed for NASA-Langley Research Center which calculates sound levels at receiver positions either on a uniform grid or at specific defined locations. The basic computational model calculates a variety of metria. Acoustic properties of the noise source are defined by two sets of sound pressure hemispheres, each hemisphere being centered on a noise source of the aircraft. One set of sound hemispheres provides the broadband data in the form of one-third octave band sound levels. The other set of sound hemispheres provides narrowband data in the form of pure-tone sound pressure levels and phase. Noise contours on the ground are output graphically or in tabular format, and are suitable for inclusion in Environmental Impact Statements or Environmental Assessments.

Analysis of impact noise induced by hitting of titanium head golf driver.

PubMed

Kim, Young Ho; Kim, Young Chul; Lee, Jun Hee; An, Yong-Hwi; Park, Kyung Tae; Kang, Kyung Min; Kang, Yeon June

2014-11-01

The hitting of titanium head golf driver against golf ball creates a short duration, high frequency impact noise. We analyzed the spectra of these impact noises and evaluated the auditory hazards from exposure to the noises. Noises made by 10 titanium head golf drivers with five maximum hits were collected, and the spectra of the pure impact sounds were studied using a noise analysis program. The noise was measured at 1.7 m (position A) and 3.4 m (position B) from the hitting point in front of the hitter and at 3.4 m (position C) behind the hitting point. Average time duration was measured and auditory risk units (ARUs) at position A were calculated using the Auditory Hazard Assessment Algorithm for Humans. The average peak levels at position A were 119.9 dBA at the sound pressure level (SPL) peak and 100.0 dBA at the overall octave level. The average peak levels (SPL and overall octave level) at position B were 111.6 and 96.5 dBA, respectively, and at position C were 111.5 and 96.7 dBA, respectively. The average time duration and ARUs measured at position A were 120.6 ms and 194.9 units, respectively. Although impact noises made by titanium head golf drivers showed relatively low ARUs, individuals enjoying golf frequently may be susceptible to hearing loss due to the repeated exposure of this intense impact noise with short duration and high frequency. Unprotected exposure to impact noises should be limited to prevent cochleovestibular disorders.

Bacillus subtilis spores on artificial meteorites survive hypervelocity atmospheric entry: implications for Lithopanspermia.

PubMed

Fajardo-Cavazos, Patricia; Link, Lindsey; Melosh, H Jay; Nicholson, Wayne L

2005-12-01

An important but untested aspect of the lithopanspermia hypothesis is that microbes situated on or within meteorites could survive hypervelocity entry from space through Earth's atmosphere. The use of high-altitude sounding rockets to test this notion was explored. Granite samples permeated with spores of Bacillus subtilis strain WN511 were attached to the exterior telemetry module of a sounding rocket and launched from White Sands Missile Range, New Mexico into space, reaching maximum atmospheric entry velocity of 1.2 km/s. Maximum recorded temperature during the flight was measured at 145 degrees C. The surfaces of the post-flight granite samples were swabbed and tested for recovery and survival of WN511 spores, using genetic markers and the unique DNA fingerprint of WN511 as recovery criteria. Spore survivors were isolated at high frequency, ranging from 1.2% to 4.4% compared with ground controls, from all surfaces except the forward-facing surface. Sporulation-defective mutants were noted among the spaceflight survivors at high frequency (4%). These experiments constitute the first report of spore survival to hypervelocity atmospheric transit, and indicate that sounding rocket flights can be used to model the high-speed atmospheric entry of bacteria-laden artificial meteorites.

Bacillus subtilis Spores on Artificial Meteorites Survive Hypervelocity Atmospheric Entry: Implications for Lithopanspermia

NASA Astrophysics Data System (ADS)

Fajardo-Cavazos, Patricia; Link, Lindsey; Melosh, H. Jay; Nicholson, Wayne L.

2005-12-01

An important but untested aspect of the lithopanspermia hypothesis is that microbes situated on or within meteorites could survive hypervelocity entry from space through Earth's atmosphere. The use of high-altitude sounding rockets to test this notion was explored. Granite samples permeated with spores of Bacillus subtilis strain WN511 were attached to the exterior telemetry module of a sounding rocket and launched from White Sands Missile Range, New Mexico into space, reaching maximum atmospheric entry velocity of 1.2 km/s. Maximum recorded temperature during the flight was measured at 145°C. The surfaces of the post-flight granite samples were swabbed and tested for recovery and survival of WN511 spores, using genetic markers and the unique DNA fingerprint of WN511 as recovery criteria. Spore survivors were isolated at high frequency, ranging from 1.2% to 4.4% compared with ground controls, from all surfaces except the forward-facing surface. Sporulation-defective mutants were noted among the spaceflight survivors at high frequency (4%). These experiments constitute the first report of spore survival to hypervelocity atmospheric transit, and indicate that sounding rocket flights can be used to model the high-speed atmospheric entry of bacteria-laden artificial meteorites.

Comparison of Travel-Time and Amplitude Measurements for Deep-Focusing Time-Distance Helioseismology

NASA Astrophysics Data System (ADS)

Pourabdian, Majid; Fournier, Damien; Gizon, Laurent

2018-04-01

The purpose of deep-focusing time-distance helioseismology is to construct seismic measurements that have a high sensitivity to the physical conditions at a desired target point in the solar interior. With this technique, pairs of points on the solar surface are chosen such that acoustic ray paths intersect at this target (focus) point. Considering acoustic waves in a homogeneous medium, we compare travel-time and amplitude measurements extracted from the deep-focusing cross-covariance functions. Using a single-scattering approximation, we find that the spatial sensitivity of deep-focusing travel times to sound-speed perturbations is zero at the target location and maximum in a surrounding shell. This is unlike the deep-focusing amplitude measurements, which have maximum sensitivity at the target point. We compare the signal-to-noise ratio for travel-time and amplitude measurements for different types of sound-speed perturbations, under the assumption that noise is solely due to the random excitation of the waves. We find that, for highly localized perturbations in sound speed, the signal-to-noise ratio is higher for amplitude measurements than for travel-time measurements. We conclude that amplitude measurements are a useful complement to travel-time measurements in time-distance helioseismology.

Using LiDAR to quantify uplift of shoreline angles during late Holocene earthquakes in northwest Washington

NASA Astrophysics Data System (ADS)

Sherrod, B. L.

2014-12-01

Three reverse faults in northwestern Washington - the Seattle, Tacoma, and Birch Bay faults - experienced late Holocene earthquakes. Warped intertidal platforms in the hanging wall of each fault formed broad anticlines as a result of deformation during these three earthquakes. Estimates of past deformation rely on differencing raised shoreline features and corresponding modern features. I utilized profiles of LiDAR digital elevation models to calculate prehistoric (647 profiles) and modern shoreline angles (507 profiles) and used these angles to quantify the shape and amount of deformation of each anticline. I calculated shoreline angle elevations by visually fitting lines to modern and uplifted intertidal surfaces and adjacent shoreline cliffs. The intersection of the two fitted lines is the shoreline angle. Mean elevations of modern shoreline angles for 6 shoreline areas in northern Puget Sound and the Strait of Georgia (n=507) lie within 2-46 cm of mean tide level. Three additional shoreline areas in southern Puget Sound have modern shoreline angles closer to mean higher high water (within 22-88 cm) and lie in areas with less fetch and greater tidal range than sites in northern Puget Sound and the Straits of Georgia. A M>7 earthquake ~1.1 ka on the Seattle fault lifted a broad platform cut on sedimentary rocks out of the intertidal zone. Profiles of the platform at three locations along the western end of the Seattle fault zone define an anticline 8-10 km wide (orthogonal to the fault) with a maximum uplift during the earthquake of ~5-8 m. Another large earthquake ~1.1 ka uplifted an intertidal platform along the western part of the Tacoma fault. The raised platform formed an anticline ~10 km wide (orthogonal to the fault) with a maximum uplift of ~5 m. An earthquake ~1.2 ka raised shorelines in the hanging wall of the Birch Bay fault above an anticline observed on seismic reflection profiles near Bellingham, WA. Only part of the anticline is expressed in raised shorelines because shoreline angles are not preserved in the northern limb of the anticline. Estimated width of the anticline is ~8 km with a maximum uplift of 2.5 m. Ongoing elastic half-space modeling is intended to match profiles of each raised shoreline in order to estimate fault geometries and earthquake magnitudes required to produce the observed uplift profiles.

Sound Pressure Levels Measured in a University Concert Band: A Risk of Noise-Induced Hearing Loss?

ERIC Educational Resources Information Center

Holland, Nicholas V., III

2008-01-01

Researchers have reported public school band directors as experiencing noise-induced hearing loss. Little research has focused on collegiate band directors and university student musicians. The present study measures the sound pressure levels generated within a university concert band and compares sound levels with the criteria set by the…

49 CFR 210.31 - Operation standards (stationary locomotives at 30 meters).

Code of Federal Regulations, 2011 CFR

2011-10-01

... prescribed in paragraph (a)(2) of this section, the A-weighted sound level reading in decibels shall be... A-weighted sound level reading in decibels that is observed during the 30-second period of time... test; (3) Date of test; and (4) The A-weighted sound level reading in decibels obtained during the...

Statistical Analysis for Subjective and Objective Evaluations of Dental Drill Sounds

PubMed Central

Yamada, Tomomi; Kuwano, Sonoko; Ebisu, Shigeyuki; Hayashi, Mikako

2016-01-01

The sound produced by a dental air turbine handpiece (dental drill) can markedly influence the sound environment in a dental clinic. Indeed, many patients report that the sound of a dental drill elicits an unpleasant feeling. Although several manufacturers have attempted to reduce the sound pressure levels produced by dental drills during idling based on ISO 14457, the sound emitted by such drills under active drilling conditions may negatively influence the dental clinic sound environment. The physical metrics related to the unpleasant impressions associated with dental drill sounds have not been determined. In the present study, psychological measurements of dental drill sounds were conducted with the aim of facilitating improvement of the sound environment at dental clinics. Specifically, we examined the impressions elicited by the sounds of 12 types of dental drills in idling and drilling conditions using a semantic differential. The analysis revealed that the impressions of dental drill sounds varied considerably between idling and drilling conditions and among the examined drills. This finding suggests that measuring the sound of a dental drill in idling conditions alone may be insufficient for evaluating the effects of the sound. We related the results of the psychological evaluations to those of measurements of the physical metrics of equivalent continuous A-weighted sound pressure levels (LAeq) and sharpness. Factor analysis indicated that impressions of the dental drill sounds consisted of two factors: “metallic and unpleasant” and “powerful”. LAeq had a strong relationship with “powerful impression”, calculated sharpness was positively related to “metallic impression”, and “unpleasant impression” was predicted by the combination of both LAeq and calculated sharpness. The present analyses indicate that, in addition to a reduction in sound pressure level, refining the frequency components of dental drill sounds is important for creating a comfortable sound environment in dental clinics. PMID:27462903

Differences between Outdoor and Indoor Sound Levels for Open, Tilted, and Closed Windows

PubMed Central

Locher, Barbara; Piquerez, André; Habermacher, Manuel; Ragettli, Martina; Cajochen, Christian; Vienneau, Danielle; Foraster, Maria; Müller, Uwe; Wunderli, Jean Marc

2018-01-01

Noise exposure prediction models for health effect studies normally estimate free field exposure levels outside. However, to assess the noise exposure inside dwellings, an estimate of indoor sound levels is necessary. To date, little field data is available about the difference between indoor and outdoor noise levels and factors affecting the damping of outside noise. This is a major cause of uncertainty in indoor noise exposure prediction and may lead to exposure misclassification in health assessments. This study aims to determine sound level differences between the indoors and the outdoors for different window positions and how this sound damping is related to building characteristics. For this purpose, measurements were carried out at home in a sample of 102 Swiss residents exposed to road traffic noise. Sound pressure level recordings were performed outdoors and indoors, in the living room and in the bedroom. Three scenarios—of open, tilted, and closed windows—were recorded for three minutes each. For each situation, data on additional parameters such as the orientation towards the source, floor, and room, as well as sound insulation characteristics were collected. On that basis, linear regression models were established. The median outdoor–indoor sound level differences were of 10 dB(A) for open, 16 dB(A) for tilted, and 28 dB(A) for closed windows. For open and tilted windows, the most relevant parameters affecting the outdoor–indoor differences were the position of the window, the type and volume of the room, and the age of the building. For closed windows, the relevant parameters were the sound level outside, the material of the window frame, the existence of window gaskets, and the number of windows. PMID:29346318

Differences between Outdoor and Indoor Sound Levels for Open, Tilted, and Closed Windows.

PubMed

Locher, Barbara; Piquerez, André; Habermacher, Manuel; Ragettli, Martina; Röösli, Martin; Brink, Mark; Cajochen, Christian; Vienneau, Danielle; Foraster, Maria; Müller, Uwe; Wunderli, Jean Marc

2018-01-18

Noise exposure prediction models for health effect studies normally estimate free field exposure levels outside. However, to assess the noise exposure inside dwellings, an estimate of indoor sound levels is necessary. To date, little field data is available about the difference between indoor and outdoor noise levels and factors affecting the damping of outside noise. This is a major cause of uncertainty in indoor noise exposure prediction and may lead to exposure misclassification in health assessments. This study aims to determine sound level differences between the indoors and the outdoors for different window positions and how this sound damping is related to building characteristics. For this purpose, measurements were carried out at home in a sample of 102 Swiss residents exposed to road traffic noise. Sound pressure level recordings were performed outdoors and indoors, in the living room and in the bedroom. Three scenarios-of open, tilted, and closed windows-were recorded for three minutes each. For each situation, data on additional parameters such as the orientation towards the source, floor, and room, as well as sound insulation characteristics were collected. On that basis, linear regression models were established. The median outdoor-indoor sound level differences were of 10 dB(A) for open, 16 dB(A) for tilted, and 28 dB(A) for closed windows. For open and tilted windows, the most relevant parameters affecting the outdoor-indoor differences were the position of the window, the type and volume of the room, and the age of the building. For closed windows, the relevant parameters were the sound level outside, the material of the window frame, the existence of window gaskets, and the number of windows.

Three-dimensional tracking of Cuvier's beaked whales' echolocation sounds using nested hydrophone arrays.

PubMed

Gassmann, Martin; Wiggins, Sean M; Hildebrand, John A

2015-10-01

Cuvier's beaked whales (Ziphius cavirostris) were tracked using two volumetric small-aperture (∼1 m element spacing) hydrophone arrays, embedded into a large-aperture (∼1 km element spacing) seafloor hydrophone array of five nodes. This array design can reduce the minimum number of nodes that are needed to record the arrival of a strongly directional echolocation sound from 5 to 2, while providing enough time-differences of arrivals for a three-dimensional localization without depending on any additional information such as multipath arrivals. To illustrate the capabilities of this technique, six encounters of up to three Cuvier's beaked whales were tracked over a two-month recording period within an area of 20 km(2) in the Southern California Bight. Encounter periods ranged from 11 min to 33 min. Cuvier's beaked whales were found to reduce the time interval between echolocation clicks while alternating between two inter-click-interval regimes during their descent towards the seafloor. Maximum peak-to-peak source levels of 179 and 224 dB re 1 μPa @ 1 m were estimated for buzz sounds and on-axis echolocation clicks (directivity index = 30 dB), respectively. Source energy spectra of the on-axis clicks show significant frequency components between 70 and 90 kHz, in addition to their typically noted FM upsweep at 40-60 kHz.

A comparison between Nimbus 5 THIR and ITPR temperatures and derived winds with rawinsonde data obtained in the AVE 2 experiment

NASA Technical Reports Server (NTRS)

Arnold, J. E.; Scoggins, J. R.; Fuelberg, H. E.

1976-01-01

During the period of May 11 and 12, 1974, NASA conducted its second Atmospheric Variability Experiment (AVE II) over the eastern United States. In this time interval, two Nimbus 5 orbits crossed the AVE II area, providing a series of ITPR soundings as well as THIR data. Horizontal temperature mapping of the AVE II cloud field is examined using two grid print map scales. Implied cloud top heights are compared with maximum radar-echo top reports. In addition, shelter temperatures in areas of clear sky are compared with the surface temperatures as determined from 11.5 micrometer radiometer data of the THIR experiment. The ITPR sounding accuracy is evaluated using interpolated radiosonde temperatures at times nearly coincident with the ITPR soundings. It was found that mean differences between the two data sets were as small as 1.3 C near 500 mb and as large as 2.9 C near the tropopause. The differences between ITPR and radiosonde temperatures at constant pressure levels were sufficient to induce significant differences in the horizontal temperature gradient. Cross sections of geostrophic wind along the orbital tracks were developed using a thermal wind buildup based on the ITPR temperature data and the radiosonde temperature data. Differences between the radiosonde and ITPR geostrophic winds could be explained on the basis of differences in the ITPR and radiosonde temperature gradients.

Multifunctional Device based on phosphor-piezoelectric PZT: lighting, speaking, and mechanical energy harvesting.

PubMed

Lee, Sunghoon; Kang, Taewook; Lee, Wunho; Afandi, Mohammad M; Ryu, Jongho; Kim, Jongsu

2018-01-10

We demonstrated the tri-functional device based on all powder-processing methods by using ZnS powder as phosphor layer and piezoelectric material as dielectric layer. The fabricated device generated the electroluminescent (EL) light from phosphor and the sound from piezoelectric sheet under a supply of external electric power, and additionally harvested the reverse-piezoelectric energy to be converted into EL light. Under sinusoidal applied voltage, EL luminances were exponentially increased with a maximum luminous efficiency of 1.3 lm/W at 40 V and 1,000 Hz, and sound pressure levels (SPLs) were linearly increased. The EL luminances were linearly dependent on applied frequency while the SPLs showed the parabolic increase behavior below 1,000 Hz and then the flat response. The temperature dependence on EL luminances and SPLs was demonstrated; the former was drastically increased and the latter was slightly decreased with the increase of temperature. Finally, as an energy harvesting application, the piezoelectric-induced electroluminescence effect was demonstrated by applying only mechanical pressure to the device without any external electric power.

Inulin and erythritol as sucrose replacers in short-dough cookies: sensory, fracture, and acoustic properties.

PubMed

Laguna, Laura; Primo-Martín, Cristina; Salvador, Ana; Sanz, Teresa

2013-05-01

The effect of sucrose replacement by erythritol and inulin was studied in short-dough cookies using instrumental and sensory analysis. Two levels of replacement were used (25% and 50% of total sucrose content). Descriptive sensory analysis showed that the sucrose replacement affects visual and texture cookies characteristics, being the differences perceived by mouth greater than by hand. In general, sucrose substitutes produced a less crispy cookie and lower consumer acceptability, with the exception of 25% sucrose replacement by inulin. Matrix aeration attributes such as open and crumbly obtained by trained panel were important properties, and correlated positively with consumer acceptance and negatively with maximum force at break (hardness). Inulin cookies sensory properties were more similar to the control than the erythritol cookies. Also, consumer overall acceptance decreased significantly with sucrose replacement by erythritol. The analysis of texture and sound revealed that inulin cookies were softer whereas erythritol cookies were harder in comparison with control cookies; despite this difference, inulin cookies had similar sound characteristics to erythritol cookies. © 2013 Institute of Food Technologists®

[Echolocation calls of free-flying Himalayan swiftlets (Aerodramus brevirostris)].

PubMed

Wang, Bin; Ma, Jian-Zhang; Chen, Yi; Tan, Liang-Jing; Liu, Qi; Shen, Qi-Qi; Liao, Qing-Yi; Zhang, Li-Biao

2013-02-01

Here, we present our findings of free-flying echolocation calls of Himalayan swiftlets (Aerodramus brevirostris), which were recorded in Shenjing Cave, Hupingshan National Reserve, Shimen County, Hunan Province in June 2012, using Avisoft-UltraSoundGate 116(e). We noted that after foraging at dusk, the Himalayan swiftlets flew fast into the cave without clicks, and then slowed down in dark area in the cave, but with sounds. The echolocation sounds of Himalayan swiftlets are broadband, double noise burst clicks, separated by a short pause. The inter-pulse intervals between double clicks (99.3±3.86 ms)were longer than those within double clicks (6.6±0.42 ms) (P<0.01). With the exception of peak frequency, between 6.2±0.08 kHz and 6.2±0.10 kHz, (P>0.05) and pulse duration 2.9±0.12 ms, 3.2±0.17 ms, (P>0.05) between the first and second, other factors-maximum frequency, minimum frequency, frequency bandwidth, and power-were significantly different between the clicks. The maximum frequency of the first pulse (20.1±1.10 kHz) was higher than that of second (15.4±0.98 kHz) (P<0.01), while the minimum frequency of the first pulse (3.7±0.12 kHz) was lower than that of second (4.0±0.09 kHz) (P<0.05); resulting in the frequency bandwidth of the first pulse (16.5±1.17 kHz) longer than that of second (11.4±1.01 kHz) (P<0.01). The power of the first pulse (-32.5±0.60 dB) was higher than that of second (-35.2±0.94 dB) (P<0.05). More importantly, we found that Himalayan swiftlets emitted echolocation pulses including ultrasonic sound, with a maximum frequency reaching 33.2 kHz.

Exploratory investigation of sound pressure level in the wake of an oscillating airfoil in the vicinity of stall

NASA Technical Reports Server (NTRS)

Gray, R. B.; Pierce, G. A.

1972-01-01

Wind tunnel tests were performed on two oscillating two-dimensional lifting surfaces. The first of these models had an NACA 0012 airfoil section while the second simulated the classical flat plate. Both of these models had a mean angle of attack of 12 degrees while being oscillated in pitch about their midchord with a double amplitude of 6 degrees. Wake surveys of sound pressure level were made over a frequency range from 16 to 32 Hz and at various free stream velocities up to 100 ft/sec. The sound pressure level spectrum indicated significant peaks in sound intensity at the oscillation frequency and its first harmonic near the wake of both models. From a comparison of these data with that of a sound level meter, it is concluded that most of the sound intensity is contained within these peaks and no appreciable peaks occur at higher harmonics. It is concluded that within the wake the sound intensity is largely pseudosound while at one chord length outside the wake, it is largely true vortex sound. For both the airfoil and flat plate the peaks appear to be more strongly dependent upon the airspeed than on the oscillation frequency. Therefore reduced frequency does not appear to be a significant parameter in the generation of wake sound intensity.

The improvement of a simple theoretical model for the prediction of the sound insulation of double leaf walls.

PubMed

Davy, John L

2010-02-01

This paper presents a revised theory for predicting the sound insulation of double leaf cavity walls that removes an approximation, which is usually made when deriving the sound insulation of a double leaf cavity wall above the critical frequencies of the wall leaves due to the airborne transmission across the wall cavity. This revised theory is also used as a correction below the critical frequencies of the wall leaves instead of a correction due to Sewell [(1970). J. Sound Vib. 12, 21-32]. It is found necessary to include the "stud" borne transmission of the window frames when modeling wide air gap double glazed windows. A minimum value of stud transmission is introduced for use with resilient connections such as steel studs. Empirical equations are derived for predicting the effective sound absorption coefficient of wall cavities without sound absorbing material. The theory is compared with experimental results for double glazed windows and gypsum plasterboard cavity walls with and without sound absorbing material in their cavities. The overall mean, standard deviation, maximum, and minimum of the differences between experiment and theory are -0.6 dB, 3.1 dB, 10.9 dB at 1250 Hz, and -14.9 dB at 160 Hz, respectively.

The influence of underwater data transmission sounds on the displacement behaviour of captive harbour seals (Phoca vitulina).

PubMed

Kastelein, Ronald A; van der Heul, Sander; Verboom, Willem C; Triesscheijn, Rob J V; Jennings, Nancy V

2006-02-01

To prevent grounding of ships and collisions between ships in shallow coastal waters, an underwater data collection and communication network (ACME) using underwater sounds to encode and transmit data is currently under development. Marine mammals might be affected by ACME sounds since they may use sound of a similar frequency (around 12 kHz) for communication, orientation, and prey location. If marine mammals tend to avoid the vicinity of the acoustic transmitters, they may be kept away from ecologically important areas by ACME sounds. One marine mammal species that may be affected in the North Sea is the harbour seal (Phoca vitulina). No information is available on the effects of ACME-like sounds on harbour seals, so this study was carried out as part of an environmental impact assessment program. Nine captive harbour seals were subjected to four sound types, three of which may be used in the underwater acoustic data communication network. The effect of each sound was judged by comparing the animals' location in a pool during test periods to that during baseline periods, during which no sound was produced. Each of the four sounds could be made into a deterrent by increasing its amplitude. The seals reacted by swimming away from the sound source. The sound pressure level (SPL) at the acoustic discomfort threshold was established for each of the four sounds. The acoustic discomfort threshold is defined as the boundary between the areas that the animals generally occupied during the transmission of the sounds and the areas that they generally did not enter during transmission. The SPLs at the acoustic discomfort thresholds were similar for each of the sounds (107 dB re 1 microPa). Based on this discomfort threshold SPL, discomfort zones at sea for several source levels (130-180 dB re 1 microPa) of the sounds were calculated, using a guideline sound propagation model for shallow water. The discomfort zone is defined as the area around a sound source that harbour seals are expected to avoid. The definition of the discomfort zone is based on behavioural discomfort, and does not necessarily coincide with the physical discomfort zone. Based on these results, source levels can be selected that have an acceptable effect on harbour seals in particular areas. The discomfort zone of a communication sound depends on the sound, the source level, and the propagation characteristics of the area in which the sound system is operational. The source level of the communication system should be adapted to each area (taking into account the width of a sea arm, the local sound propagation, and the importance of an area to the affected species). The discomfort zone should not coincide with ecologically important areas (for instance resting, breeding, suckling, and feeding areas), or routes between these areas.

Investigation of Noise Field and Velocity Profiles of an Afterburning Engine

NASA Technical Reports Server (NTRS)

North, Warren J.; Callaghan, E. E.; Lanzo, C. D.

1954-01-01

Sound pressure levels, frequency spectrum, and jet velocity profiles are presented for an engine-afterburner combination at various values of afterburner fuel - air ratio. At the high fuel-air ratios, severe low-frequency resonance was encountered which represented more than half the total energy in the sound spectrum. At similar thrust conditions, lower sound pressure levels were obtained from a current fighter air craft with a different afterburner configuration. The lower sound pressure levels are attributed to resonance-free afterburner operation and thereby indicate the importance of acoustic considerations in afterburner design.

Effects of Sound on the Behavior of Wild, Unrestrained Fish Schools.

PubMed

Roberts, Louise; Cheesman, Samuel; Hawkins, Anthony D

2016-01-01

To assess and manage the impact of man-made sounds on fish, we need information on how behavior is affected. Here, wild unrestrained pelagic fish schools were observed under quiet conditions using sonar. Fish were exposed to synthetic piling sounds at different levels using custom-built sound projectors, and behavioral changes were examined. In some cases, the depth of schools changed after noise playback; full dispersal of schools was also evident. The methods we developed for examining the behavior of unrestrained fish to sound exposure have proved successful and may allow further testing of the relationship between responsiveness and sound level.

The influence of sea ice, wind speed and marine mammals on Southern Ocean ambient sound.

PubMed

Menze, Sebastian; Zitterbart, Daniel P; van Opzeeland, Ilse; Boebel, Olaf

2017-01-01

This paper describes the natural variability of ambient sound in the Southern Ocean, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by Antarctic blue whales ( Balaenoptera musculus intermedia ), fin whales ( Balaenoptera physalus ), Antarctic minke whales ( Balaenoptera bonaerensis ) and leopard seals ( Hydrurga leptonyx ). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The Antarctic blue and fin whale contributions were loudest in austral autumn, whereas the Antarctic minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton.

The influence of sea ice, wind speed and marine mammals on Southern Ocean ambient sound

NASA Astrophysics Data System (ADS)

Menze, Sebastian; Zitterbart, Daniel P.; van Opzeeland, Ilse; Boebel, Olaf

2017-01-01

This paper describes the natural variability of ambient sound in the Southern Ocean, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by Antarctic blue whales (Balaenoptera musculus intermedia), fin whales (Balaenoptera physalus), Antarctic minke whales (Balaenoptera bonaerensis) and leopard seals (Hydrurga leptonyx). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The Antarctic blue and fin whale contributions were loudest in austral autumn, whereas the Antarctic minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton.

School Sound Level Study.

ERIC Educational Resources Information Center

California State Dept. of Education, Sacramento.

California has conducted on-site sound surveys of 36 different schools to determine the degree of noise, and thus disturbance, within the learning environment. This report provides the methodology and results of the survey, including descriptive charts and graphs illustrating typical desirable and undesirable sound levels. Results are presented…

30 CFR 62.101 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 85 dBA, or equivalently a dose of 50%, integrating all sound levels from 80 dBA to at least 130 dBA... Protection Level. A TWA8 of 105 dBA, or equivalently, a dose of 800% of that permitted by the standard, integrating all sound levels from 90 dBA to at least 140 dBA. Exchange rate. The amount of increase in sound...

30 CFR 62.101 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 85 dBA, or equivalently a dose of 50%, integrating all sound levels from 80 dBA to at least 130 dBA... Protection Level. A TWA8 of 105 dBA, or equivalently, a dose of 800% of that permitted by the standard, integrating all sound levels from 90 dBA to at least 140 dBA. Exchange rate. The amount of increase in sound...

40 CFR 201.11 - Standard for locomotive operation under stationary conditions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... completed on or before December 31, 1979, which produces A-weighted sound levels in excess of 93 dB at any..., 1979, which produces A-weighted sound levels in excess of 87 dB at any throttle setting except idle... December 31, 1979, which produces A-weighted sound levels in excess of 87 dB at any throttle setting except...

40 CFR 201.11 - Standard for locomotive operation under stationary conditions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... completed on or before December 31, 1979, which produces A-weighted sound levels in excess of 93 dB at any..., 1979, which produces A-weighted sound levels in excess of 87 dB at any throttle setting except idle... December 31, 1979, which produces A-weighted sound levels in excess of 87 dB at any throttle setting except...

Sound level-dependent growth of N1m amplitude with low and high-frequency tones.

PubMed

Soeta, Yoshiharu; Nakagawa, Seiji

2009-04-22

The aim of this study was to determine whether the amplitude and/or latency of the N1m deflection of auditory-evoked magnetic fields are influenced by the level and frequency of sound. The results indicated that the amplitude of the N1m increased with sound level. The growth in amplitude with increasing sound level was almost constant with low frequencies (250-1000 Hz); however, this growth decreased with high frequencies (>2000 Hz). The behavior of the amplitude may reflect a difference in the increase in the activation of the peripheral and/or central auditory systems.

What the Toadfish Ear Tells the Toadfish Brain About Sound.

PubMed

Edds-Walton, Peggy L

2016-01-01

Of the three, paired otolithic endorgans in the ear of teleost fishes, the saccule is the one most often demonstrated to have a major role in encoding frequencies of biologically relevant sounds. The toadfish saccule also encodes sound level and sound source direction in the phase-locked activity conveyed via auditory afferents to nuclei of the ipsilateral octaval column in the medulla. Although paired auditory receptors are present in teleost fishes, binaural processes were believed to be unimportant due to the speed of sound in water and the acoustic transparency of the tissues in water. In contrast, there are behavioral and anatomical data that support binaural processing in fishes. Studies in the toadfish combined anatomical tract-tracing and physiological recordings from identified sites along the ascending auditory pathway to document response characteristics at each level. Binaural computations in the medulla and midbrain sharpen the directional information provided by the saccule. Furthermore, physiological studies in the central nervous system indicated that encoding frequency, sound level, temporal pattern, and sound source direction are important components of what the toadfish ear tells the toadfish brain about sound.

Repeated imitation makes human vocalizations more word-like.

PubMed

Edmiston, Pierce; Perlman, Marcus; Lupyan, Gary

2018-03-14

People have long pondered the evolution of language and the origin of words. Here, we investigate how conventional spoken words might emerge from imitations of environmental sounds. Does the repeated imitation of an environmental sound gradually give rise to more word-like forms? In what ways do these forms resemble the original sounds that motivated them (i.e. exhibit iconicity)? Participants played a version of the children's game 'Telephone'. The first generation of participants imitated recognizable environmental sounds (e.g. glass breaking, water splashing). Subsequent generations imitated the previous generation of imitations for a maximum of eight generations. The results showed that the imitations became more stable and word-like, and later imitations were easier to learn as category labels. At the same time, even after eight generations, both spoken imitations and their written transcriptions could be matched above chance to the category of environmental sound that motivated them. These results show how repeated imitation can create progressively more word-like forms while continuing to retain a resemblance to the original sound that motivated them, and speak to the possible role of human vocal imitation in explaining the origins of at least some spoken words. © 2018 The Author(s).

MP3 player listening sound pressure levels among 10 to 17 year old students.

PubMed

Keith, Stephen E; Michaud, David S; Feder, Katya; Haider, Ifaz; Marro, Leonora; Thompson, Emma; Marcoux, Andre M

2011-11-01

Using a manikin, equivalent free-field sound pressure level measurements were made from the portable digital audio players of 219 subjects, aged 10 to 17 years (93 males) at their typical and "worst-case" volume levels. Measurements were made in different classrooms with background sound pressure levels between 40 and 52 dBA. After correction for the transfer function of the ear, the median equivalent free field sound pressure levels and interquartile ranges (IQR) at typical and worst-case volume settings were 68 dBA (IQR = 15) and 76 dBA (IQR = 19), respectively. Self-reported mean daily use ranged from 0.014 to 12 h. When typical sound pressure levels were considered in combination with the average daily duration of use, the median noise exposure level, Lex, was 56 dBA (IQR = 18) and 3.2% of subjects were estimated to exceed the most protective occupational noise exposure level limit in Canada, i.e., 85 dBA Lex. Under worst-case listening conditions, 77.6% of the sample was estimated to listen to their device at combinations of sound pressure levels and average daily durations for which there is no known risk of permanent noise-induced hearing loss, i.e., ≤  75 dBA Lex. Sources and magnitudes of measurement uncertainties are also discussed.

Modeling of the dolphin's clicking sound source: The influence of the critical parameters

NASA Astrophysics Data System (ADS)

Dubrovsky, N. A.; Gladilin, A.; Møhl, B.; Wahlberg, M.

2004-07-01

A physical and a mathematical models of the dolphin’s source of echolocation clicks have been recently proposed. The physical model includes a bottle of pressurized air connected to the atmosphere with an underwater rubber tube. A compressing rubber ring is placed on the underwater portion of the tube. The ring blocks the air jet passing through the tube from the bottle. This ring can be brought into self-oscillation by the air jet. In the simplest case, the ring displacement follows a repeated triangular waveform. Because the acoustic pressure gradient is proportional to the second time derivative of the displacement, clicks arise at the bends of the displacement waveform. The mathematical model describes the dipole oscillations of a sphere “frozen” in the ring and calculates the waveform and the sound pressure of the generated clicks. The critical parameters of the mathematical model are the radius of the sphere and the peak value and duration of the triangular displacement curve. This model allows one to solve both the forward (deriving the properties of acoustic clicks from the known source parameters) and the inverse (calculating the source parameters from the acoustic data) problems. Data from click records of Odontocetes were used to derive both the displacement waveforms and the size of the “frozen sphere” or a structure functionally similar to it. The mathematical model predicts a maximum source level of up to 235 dB re 1 μPa at 1-m range when using a 5-cm radius of the “frozen” sphere and a 4-mm maximal displacement. The predicted sound pressure level is similar to that of the clicks produced by Odontocetest.

41 CFR 50-204.10 - Occupational noise exposure.

Code of Federal Regulations, 2010 CFR

2010-07-01

... determined as follows: EC21OC91.015 Equivalent sound level contours. Octave band sound pressure levels may be... level dBA slow response 8 90 6 92 4 95 3 97 2 100 11/2 102 1 105 1/2 110 1/4 or less 115 1 When the... not exceed 140 dB peak sound pressure level. [34 FR 7946, May 20, 1969, as amended at 35 FR 1015, Jan...

41 CFR 50-204.10 - Occupational noise exposure.

Code of Federal Regulations, 2011 CFR

2011-07-01

... determined as follows: EC21OC91.015 Equivalent sound level contours. Octave band sound pressure levels may be... level dBA slow response 8 90 6 92 4 95 3 97 2 100 11/2 102 1 105 1/2 110 1/4 or less 115 1 When the... not exceed 140 dB peak sound pressure level. [34 FR 7946, May 20, 1969, as amended at 35 FR 1015, Jan...

Forced Mixer Nozzle Optimization

NASA Technical Reports Server (NTRS)

Sheoran, Yogi; Hoover, Robert; Schuster, William; Anderson, Morris; Weir, Donald S.

1999-01-01

Computational fluid dynamic (CFD) and computational acoustic analyses (CAA) were performed for a TFE731-40 compound nozzle, a TFE731-60 mixer nozzle and an Energy Efficient Engine (E(sup 3)) mixer nozzle for comparison with available data. The CFD analyses were performed with a three dimensional, Navier-Stokes solution of the flowfield on an unstructured grid using the RAMPANT program. The CAA analyses were performed with the NASA Glenn MGB program using a structured grid. A successful aerodynamic solution for the TFE731-40 compound nozzle operating statically was obtained, simulating an engine operating on a test stand. Analysis of the CFD results of the TFE731-40 with the MGB program produced predicted sound power levels that agree quite well with the measured data front full-scale static engine tests. Comparison of the predicted sound pressure with the data show good agreement near the jet axis, but the noise levels are overpredicted at angles closer to the inlet. The predicted sound power level for the TFE731-60 did not agree as well with measured static engine data as the TFE731-40. Although a reduction in the predicted noise level due to the mixed flow was observed, the reduction was not as significant as the measured data. The analysis of the V2 mixer from the E(sup 3) study showed that peak temperatures predicted in the mixer exit flowfield were within 5 percent of the values measured by the exit probes. The noise predictions of the V2 mixer nozzle tended to be 3-5 dB higher in peak noise level than the measurements. In addition, the maximum frequency of the noise was also overpredicted. An analysis of the 3 candidate mixer nozzle configurations demonstrated the feasibility of using centerbody lobes and porosity to improve mixing efficiency. A final configuration was designed with a predicted thermal mixing efficiency that was 5 percent higher than the 3 candidate mixers. The results of the MGB noise calculations show that the final design will exceed the design goal of a 3 dB reduction in noise as compared to the baseline TFE731-40.

Sound Levels and Risk Perceptions of Music Students During Classes.

PubMed

Rodrigues, Matilde A; Amorim, Marta; Silva, Manuela V; Neves, Paula; Sousa, Aida; Inácio, Octávio

2015-01-01

It is well recognized that professional musicians are at risk of hearing damage due to the exposure to high sound pressure levels during music playing. However, it is important to recognize that the musicians' exposure may start early in the course of their training as students in the classroom and at home. Studies regarding sound exposure of music students and their hearing disorders are scarce and do not take into account important influencing variables. Therefore, this study aimed to describe sound level exposures of music students at different music styles, classes, and according to the instrument played. Further, this investigation attempted to analyze the perceptions of students in relation to exposure to loud music and consequent health risks, as well as to characterize preventive behaviors. The results showed that music students are exposed to high sound levels in the course of their academic activity. This exposure is potentiated by practice outside the school and other external activities. Differences were found between music style, instruments, and classes. Tinnitus, hyperacusis, diplacusis, and sound distortion were reported by the students. However, students were not entirely aware of the health risks related to exposure to high sound pressure levels. These findings reflect the importance of starting intervention in relation to noise risk reduction at an early stage, when musicians are commencing their activity as students.

Underwater sound of rigid-hulled inflatable boats.

PubMed

Erbe, Christine; Liong, Syafrin; Koessler, Matthew Walter; Duncan, Alec J; Gourlay, Tim

2016-06-01

Underwater sound of rigid-hulled inflatable boats was recorded 142 times in total, over 3 sites: 2 in southern British Columbia, Canada, and 1 off Western Australia. Underwater sound peaked between 70 and 400 Hz, exhibiting strong tones in this frequency range related to engine and propeller rotation. Sound propagation models were applied to compute monopole source levels, with the source assumed 1 m below the sea surface. Broadband source levels (10-48 000 Hz) increased from 134 to 171 dB re 1 μPa @ 1 m with speed from 3 to 16 m/s (10-56 km/h). Source power spectral density percentile levels and 1/3 octave band levels are given for use in predictive modeling of underwater sound of these boats as part of environmental impact assessments.

Monitoring the capacity of working memory: Executive control and effects of listening effort

PubMed Central

Amichetti, Nicole M.; Stanley, Raymond S.; White, Alison G.

2013-01-01

In two experiments, we used an interruption-and-recall (IAR) task to explore listeners’ ability to monitor the capacity of working memory as new information arrived in real time. In this task, listeners heard recorded word lists with instructions to interrupt the input at the maximum point that would still allow for perfect recall. Experiment 1 demonstrated that the most commonly selected segment size closely matched participants’ memory span, as measured in a baseline span test. Experiment 2 showed that reducing the sound level of presented word lists to a suprathreshold but effortful listening level disrupted the accuracy of matching selected segment sizes with participants’ memory spans. The results are discussed in terms of whether online capacity monitoring may be subsumed under other, already enumerated working memory executive functions (inhibition, set shifting, and memory updating). PMID:23400826

Distress sounds of thorny catfishes emitted underwater and in air: characteristics and potential significance.

PubMed

Knight, Lisa; Ladich, Friedrich

2014-11-15

Thorny catfishes produce stridulation (SR) sounds using their pectoral fins and drumming (DR) sounds via a swimbladder mechanism in distress situations when hand held in water and in air. It has been argued that SR and DR sounds are aimed at different receivers (predators) in different media. The aim of this study was to analyse and compare sounds emitted in both air and water in order to test different hypotheses on the functional significance of distress sounds. Five representatives of the family Doradidae were investigated. Fish were hand held and sounds emitted in air and underwater were recorded (number of sounds, sound duration, dominant and fundamental frequency, sound pressure level and peak-to-peak amplitudes). All species produced SR sounds in both media, but DR sounds could not be recorded in air for two species. Differences in sound characteristics between media were small and mainly limited to spectral differences in SR. The number of sounds emitted decreased over time, whereas the duration of SR sounds increased. The dominant frequency of SR and the fundamental frequency of DR decreased and sound pressure level of SR increased with body size across species. The hypothesis that catfish produce more SR sounds in air and more DR sounds in water as a result of different predation pressure (birds versus fish) could not be confirmed. It is assumed that SR sounds serve as distress sounds in both media, whereas DR sounds might primarily be used as intraspecific communication signals in water in species possessing both mechanisms. © 2014. Published by The Company of Biologists Ltd.

What do male singers mean by modal and falsetto register? An investigation of the glottal voice source.

PubMed

Salomão, Gláucia Laís; Sundberg, Johan

2009-01-01

The voice source differs between modal and falsetto registers, but singers often try to reduce the associated timbral differences, some even doubting that there are any. A total of 54 vowel sounds sung in falsetto and modal register by 13 male more or less experienced choir singers were analyzed by inverse filtering and electroglottography. Closed quotient, maximum flow declination rate, peak-to-peak airflow amplitude, normalized amplitude quotient, and level difference between the two lowest source spectrum partials were determined, and systematic differences were found in all singers, regardless of experience of singing. The observations seem compatible with previous observations of thicker vocal folds in modal register.

Human knee joint sound during the Lachman test: Comparison between healthy and anterior cruciate ligament-deficient knees.

PubMed

Tanaka, Kazunori; Ogawa, Munehiro; Inagaki, Yusuke; Tanaka, Yasuhito; Nishikawa, Hitoshi; Hattori, Koji

2017-05-01

The Lachman test is clinically considered to be a reliable physical examination for anterior cruciate ligament (ACL) deficiency. However, the test involves subjective judgement of differences in tibial translation and endpoint quality. An auscultation system has been developed to allow assessment of the Lachman test. The knee joint sound during the Lachman test was analyzed using fast Fourier transformation. The purpose of the present study was to quantitatively evaluate knee joint sounds in healthy and ACL-deficient human knees. Sixty healthy volunteers and 24 patients with ACL injury were examined. The Lachman test with joint auscultation was evaluated using a microphone. Knee joint sound during the Lachman test (Lachman sound) was analyzed by fast Fourier transformation. As quantitative indices of the Lachman sound, the peak sound (Lachman peak sound) as the maximum relative amplitude (acoustic pressure) and its frequency were used. In healthy volunteers, the mean Lachman peak sound of intact knees was 100.6 Hz in frequency and -45 dB in acoustic pressure. Moreover, a sex difference was found in the frequency of the Lachman peak sound. In patients with ACL injury, the frequency of the Lachman peak sound of the ACL-deficient knees was widely dispersed. In the ACL-deficient knees, the mean Lachman peak sound was 306.8 Hz in frequency and -63.1 dB in acoustic pressure. If the reference range was set at the frequency of the healthy volunteer Lachman peak sound, the sensitivity, specificity, positive predictive value, and negative predictive value were 83.3%, 95.6%, 95.2%, and 85.2%, respectively. Knee joint auscultation during the Lachman test was capable of judging ACL deficiency on the basis of objective data. In particular, the frequency of the Lachman peak sound was able to assess ACL condition. Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

Automatic Blood Pressure Measurements During Exercise

NASA Technical Reports Server (NTRS)

Weaver, Charles S.

1985-01-01

Microprocessor circuits and a computer algorithm for automatically measuring blood pressure during ambulatory monitoring and exercise stress testing have been under development at SRI International. A system that records ECG, Korotkov sound, and arm cuff pressure for off-line calculation of blood pressure has been delivered to NASA, and an LSLE physiological monitoring system that performs the algorithm calculations in real-time is being constructed. The algorithm measures the time between the R-wave peaks and the corresponding Korotkov sound on-set (RK-interval). Since the curve of RK-interval versus cuff pressure during deflation is predictable and slowly varying, windows can be set around the curve to eliminate false Korotkov sound detections that result from noise. The slope of this curve, which will generally decrease during exercise, is the inverse of the systolic slope of the brachial artery pulse. In measurements taken during treadmill stress testing, the changes in slopes of subjects with coronary artery disease were markedly different from the changes in slopes of healthy subjects. Measurements of slope and O2 consumption were also made before and after ten days of bed rest during NASA/Ames Research Center bed rest studies. Typically, the maximum rate of O2 consumption during the post-bed rest test is less than the maximum rate during the pre-bed rest test. The post-bed rest slope changes differ from the pre-bed rest slope changes, and the differences are highly correlated with the drop in the maximum rate of O2 consumption. We speculate that the differences between pre- and post-bed rest slopes are due to a drop in heart contractility.

An investigation of the sound field above the audience in large lecture halls with a scale model.

PubMed

Kahn, D W; Tichy, J

1986-09-01

Measurements of steady-state sound pressure levels above the audience in large lecture halls show that the classical equation for predicting the sound pressure level is not accurate. The direct field above the seats was measured on a 1:10 scale model and was found to be dependent on the incidence angle and direction of sound propagation across the audience. The reverberant field above the seats in the model was calculated by subtracting the direct field from the measured total field and was found to be dependent on the magnitude and particularly on the placement of absorption. The decrease of sound pressure level versus distance in the total field depends on the angle (controlled by absorption placement) at which the strong reflections are incident upon the audience area. Sound pressure level decreases at a fairly constant rate with distance from the sound source in both the direct and reverberant field, and the decrease rate depends strongly on the absorption placement. The lowest rate of decay occurs when the side walls are absorptive, and both the ceiling and rear wall are reflective. These consequences are discussed with respect to prediction of speech intelligibility.

Non-auditory health effects among air force crew chiefs exposed to high level sound.

PubMed

Jensen, Anker; Lund, Søren Peter; Lücke, Thorsten Høgh; Clausen, Ole Voldum; Svendsen, Jørgen Torp

2009-01-01

The possibility of non-auditory health effects in connection with occupational exposure to high level sound is supposed by some researchers, but is still debated. Crew chiefs on airfields are exposed to high-level aircraft sound when working close to aircraft with running engines. We compared their health status with a similar control group who were not subject to this specific sound exposure. Health records of 42 crew chiefs were compared to health records of 42 aircraft mechanics and 17 former crew chiefs. The specific sound exposure of crew chiefs was assessed. The number of reported disease cases was generally small, but generally slightly higher among mechanics than among crew chiefs. Diseases of the ear were more frequent among crew chiefs (not significant). Former crew chiefs reported fewer diseases of the ear and more airways infections (both significant). The sound exposure during launch was up to 144 dB (peak) and 124 dB (L(eq) ), but for limited time. The study did not reveal a higher disease frequency in general among crew chiefs. However, it did reveal a tendency to ear diseases, possibly due to their exposure to high-level sound.

Ultrathin, rollable, paper-based triboelectric nanogenerator for acoustic energy harvesting and self-powered sound recording.

PubMed

Fan, Xing; Chen, Jun; Yang, Jin; Bai, Peng; Li, Zhaoling; Wang, Zhong Lin

2015-04-28

A 125 μm thickness, rollable, paper-based triboelectric nanogenerator (TENG) has been developed for harvesting sound wave energy, which is capable of delivering a maximum power density of 121 mW/m(2) and 968 W/m(3) under a sound pressure of 117 dBSPL. The TENG is designed in the contact-separation mode using membranes that have rationally designed holes at one side. The TENG can be implemented onto a commercial cell phone for acoustic energy harvesting from human talking; the electricity generated can be used to charge a capacitor at a rate of 0.144 V/s. Additionally, owing to the superior advantages of a broad working bandwidth, thin structure, and flexibility, a self-powered microphone for sound recording with rolled structure is demonstrated for all-sound recording without an angular dependence. The concept and design presented in this work can be extensively applied to a variety of other circumstances for either energy-harvesting or sensing purposes, for example, wearable and flexible electronics, military surveillance, jet engine noise reduction, low-cost implantable human ear, and wireless technology applications.

Short-Range Acoustic Propagation Using Mobile Transmitters Under Arctic Ice Cover

DTIC Science & Technology

2017-09-01

predict the surface water/ice scattering and absorptive effects on transmitted sound . In addition, sound speed variability by range (usually...receivers at ranges out to 10 kilometers. Sound speed profile data was also measured on site. Transmission loss models were created as a baseline at the...received sound level (on the level of 30 to 40 decibels) at the same range and depth but different directions. 14. SUBJECT TERMS Arctic, Beaufort Sea

75 FR 39915 - Marine Mammals; File No. 15483

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-13

... whales adjust their bearing to avoid received sound pressure levels greater than 120 dB, which would... marine mammals may be taken by Level B harassment as researchers attempt to provoke an avoidance response through sound transmission into their environment. The sound source consists of a transmitter and...

40 CFR 205.54-2 - Sound data acquisition system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... meets the “fast” dynamic requirement of a precision sound level meter indicating meter system for the... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Sound data acquisition system. 205.54... data acquisition system. (a) Systems employing tape recorders and graphic level recorders may be...

An Analysis of Sound Exposure in a University Music Rehearsal

ERIC Educational Resources Information Center

Farmer, Joe; Thrasher, Michael; Fumo, Nelson

2014-01-01

Exposure to high sound levels may lead to a variety of hearing abnormalities, including Noise-Induced Hearing Loss (NIHL). Pre-professional university music majors may experience frequent exposure to elevated sound levels, and this may have implications on their future career prospects (Jansen, Helleman, Dreschler & de Laat, 2009). Studies…

The disturbance by road traffic noise of the sleep of young male adults as recorded in the home

NASA Astrophysics Data System (ADS)

Eberhardt, J. L.; Akselsson, K. R.

1987-05-01

Primary effects of road traffic noise on sleep, as derived from EEG, EOG, and EMG, were studied for seven young males (aged 21-27) in their homes along roads with heavy traffic during the night. A more quiet experimental condition was obtained by mounting sound-insulating material in the window openings, thus reducing the interiors noise level by an average of 8 dB(A). The present investigation shows that the subjects had not become completely habituated to the noise, although they had lived at least a year at their residences. The noise reduction caused an earlier onset and a prolonged duration of slow was sleep. No effects on REM sleep were seen. The subjective sleep quality was significantly correlated to the noise dose. The equivalent sound pressure level ( L eq) did not give the most adequate noise dose description. Better characterizations of the noise exposure were found in the number of car per night producing maximum sound pressure levels exceeding 50 or 55 dB(A) in the bedroom. Arousal reactions of type "body movements" and "changes towards lighter sleep" were induced by the noise of car passage but the percentage of cars inducing an effect was only <2% and <0·2% for the two types of reactions, respectively. The number of spontaneous body movements and sleep stage changes per night showed an increase during the more quiet nights as compared to the noisy nights. The sensitivity to arousal reactions was significantly lower in the present field study than the in the laboratory experiments. A description of the continuous sleep process by a few distinct "sleep stages" is too crude a tool for the detection of the rather subtle changes in the sleeping pattern caused by noise. In the present study an increased sensitivity in the analysis was obtained by dividing stage 2 into three substages.

High intensity tone generation by axisymmetric ring cavities on training projectiles

NASA Technical Reports Server (NTRS)

Parthasarathy, S. P.; Cho, Y. I.; Back, L. H.

1984-01-01

An experimental investigation has been carried out on the production of high intensity tones by axisymmetric ring cavities. Maximum sound production occurs during a double resonance at Strouhal numbers which depend only on the local flow velocity independent of cavity location. Values of sound pressure of about 115 dB at 1 meter distance can be generated by axisymmetric ring cavities on projectiles moving at a relatively low flight speed equal to 65 m/s. Frequencies in the audible range up to several Kilo Hertz can be generated aeroacoustically.

Time-dependent difference theory for noise propagation in a two-dimensional duct. [of a turbofan engine

NASA Technical Reports Server (NTRS)

Baumeister, K. J.

1979-01-01

A time dependent numerical formulation was derived for sound propagation in a two dimensional straight soft-walled duct in the absence of mean flow. The time dependent governing acoustic-difference equations and boundary conditions were developed along with the maximum stable time increment. Example calculations were presented for sound attenuation in hard and soft wall ducts. The time dependent analysis were found to be superior to the conventional steady numerical analysis because of much shorter solution times and the elimination of matrix storage requirements.

Effects of sound-field frequency modulation amplification on reducing teachers' sound pressure level in the classroom.

PubMed

Sapienza, C M; Crandell, C C; Curtis, B

1999-09-01

Voice problems are a frequent difficulty that teachers experience. Common complaints by teachers include vocal fatigue and hoarseness. One possible explanation for these symptoms is prolonged elevations in vocal loudness within the classroom. This investigation examined the effectiveness of sound-field frequency modulation (FM) amplification on reducing the sound pressure level (SPL) of the teacher's voice during classroom instruction. Specifically, SPL was examined during speech produced in a classroom lecture by 10 teachers with and without the use of sound-field amplification. Results indicated a significant 2.42-dB decrease in SPL with the use of sound-field FM amplification. These data support the use of sound-field amplification in the vocal hygiene regimen recommended to teachers by speech-language pathologists.

33 CFR 67.10-40 - Sound signals authorized for use prior to January 1, 1973.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., and 67.10-10, if the sound signal has a minimum sound pressure level as specified in Table A of... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Sound signals authorized for use... STRUCTURES General Requirements for Sound signals § 67.10-40 Sound signals authorized for use prior to...

Accuracy of assessing the level of impulse sound from distant sources.

PubMed

Wszołek, Tadeusz; Kłaczyński, Maciej

2007-01-01

Impulse sound events are characterised by ultra high pressures and low frequencies. Lower frequency sounds are generally less attenuated over a given distance in the atmosphere than higher frequencies. Thus, impulse sounds can be heard over greater distances and will be more affected by the environment. To calculate a long-term average immission level it is necessary to apply weighting factors like the probability of the occurrence of each weather condition during the relevant time period. This means that when measuring impulse noise at a long distance it is necessary to follow environmental parameters in many points along the way sound travels and also to have a database of sound transfer functions in the long term. The paper analyses the uncertainty of immission measurement results of impulse sound from cladding and destroying explosive materials. The influence of environmental conditions on the way sound travels is the focus of this paper.

Minimizing noise in fiberglass aquaculture tanks: Noise reduction potential of various retrofits

USGS Publications Warehouse

Davidson, J.; Frankel, A.S.; Ellison, W.T.; Summerfelt, S.; Popper, A.N.; Mazik, P.; Bebak, J.

2007-01-01

Equipment used in intensive aquaculture systems, such as pumps and blowers can produce underwater sound levels and frequencies within the range of fish hearing. The impacts of underwater noise on fish are not well known, but limited research suggests that subjecting fish to noise could result in impairment of the auditory system, reduced growth rates, and increased stress. Consequently, reducing sound in fish tanks could result in advantages for cultured species and increased productivity for the aquaculture industry. The objective of this study was to evaluate the noise reduction potential of various retrofits to fiberglass fish culture tanks. The following structural changes were applied to tanks to reduce underwater noise: (1) inlet piping was suspended to avoid contact with the tank, (2) effluent piping was disconnected from a common drain line, (3) effluent piping was insulated beneath tanks, and (4) tanks were elevated on cement blocks and seated on insulated padding. Four combinations of the aforementioned structural changes were evaluated in duplicate and two tanks were left unchanged as controls. Control tanks had sound levels of 120.6 dB re 1 ??Pa. Each retrofit contributed to a reduction of underwater sound. As structural changes were combined, a cumulative reduction in sound level was observed. Tanks designed with a combination of retrofits had sound levels of 108.6 dB re 1 ??Pa, a four-fold reduction in sound pressure level. Sound frequency spectra indicated that the greatest sound reductions occurred between 2 and 100 Hz and demonstrated that nearby pumps and blowers created tonal frequencies that were transmitted into the tanks. The tank modifications used during this study were simple and inexpensive and could be applied to existing systems or considered when designing aquaculture facilities. ?? 2007 Elsevier B.V. All rights reserved.

Simulated seal scarer sounds scare porpoises, but not seals: species-specific responses to 12 kHz deterrence sounds

PubMed Central

Hermannsen, Line; Beedholm, Kristian

2017-01-01

Acoustic harassment devices (AHD) or ‘seal scarers’ are used extensively, not only to deter seals from fisheries, but also as mitigation tools to deter marine mammals from potentially harmful sound sources, such as offshore pile driving. To test the effectiveness of AHDs, we conducted two studies with similar experimental set-ups on two key species: harbour porpoises and harbour seals. We exposed animals to 500 ms tone bursts at 12 kHz simulating that of an AHD (Lofitech), but with reduced output levels (source peak-to-peak level of 165 dB re 1 µPa). Animals were localized with a theodolite before, during and after sound exposures. In total, 12 sound exposures were conducted to porpoises and 13 exposures to seals. Porpoises were found to exhibit avoidance reactions out to ranges of 525 m from the sound source. Contrary to this, seal observations increased during sound exposure within 100 m of the loudspeaker. We thereby demonstrate that porpoises and seals respond very differently to AHD sounds. This has important implications for application of AHDs in multi-species habitats, as sound levels required to deter less sensitive species (seals) can lead to excessive and unwanted large deterrence ranges on more sensitive species (porpoises). PMID:28791155

The influence of sea ice, wind speed and marine mammals on Southern Ocean ambient sound

PubMed Central

van Opzeeland, Ilse; Boebel, Olaf

2017-01-01

This paper describes the natural variability of ambient sound in the Southern Ocean, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by Antarctic blue whales (Balaenoptera musculus intermedia), fin whales (Balaenoptera physalus), Antarctic minke whales (Balaenoptera bonaerensis) and leopard seals (Hydrurga leptonyx). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The Antarctic blue and fin whale contributions were loudest in austral autumn, whereas the Antarctic minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton. PMID:28280544

Why Do People Like Loud Sound? A Qualitative Study.

PubMed

Welch, David; Fremaux, Guy

2017-08-11

Many people choose to expose themselves to potentially dangerous sounds such as loud music, either via speakers, personal audio systems, or at clubs. The Conditioning, Adaptation and Acculturation to Loud Music (CAALM) Model has proposed a theoretical basis for this behaviour. To compare the model to data, we interviewed a group of people who were either regular nightclub-goers or who controlled the sound levels in nightclubs (bar managers, musicians, DJs, and sound engineers) about loud sound. Results showed four main themes relating to the enjoyment of loud sound: arousal/excitement, facilitation of socialisation, masking of both external sound and unwanted thoughts, and an emphasis and enhancement of personal identity. Furthermore, an interesting incidental finding was that sound levels appeared to increase gradually over the course of the evening until they plateaued at approximately 97 dBA Leq around midnight. Consideration of the data generated by the analysis revealed a complex of influential factors that support people in wanting exposure to loud sound. Findings were considered in terms of the CAALM Model and could be explained in terms of its principles. From a health promotion perspective, the Social Ecological Model was applied to consider how the themes identified might influence behaviour. They were shown to influence people on multiple levels, providing a powerful system which health promotion approaches struggle to address.

Psychoacoustics

NASA Astrophysics Data System (ADS)

Moore, Brian C. J.

Psychoacoustics psychological is concerned with the relationships between the physical characteristics of sounds and their perceptual attributes. This chapter describes: the absolute sensitivity of the auditory system for detecting weak sounds and how that sensitivity varies with frequency; the frequency selectivity of the auditory system (the ability to resolve or hear out the sinusoidal components in a complex sound) and its characterization in terms of an array of auditory filters; the processes that influence the masking of one sound by another; the range of sound levels that can be processed by the auditory system; the perception and modeling of loudness; level discrimination; the temporal resolution of the auditory system (the ability to detect changes over time); the perception and modeling of pitch for pure and complex tones; the perception of timbre for steady and time-varying sounds; the perception of space and sound localization; and the mechanisms underlying auditory scene analysis that allow the construction of percepts corresponding to individual sounds sources when listening to complex mixtures of sounds.

Practical ranges of loudness levels of various types of environmental noise, including traffic noise, aircraft noise, and industrial noise.

PubMed

Salomons, Erik M; Janssen, Sabine A

2011-06-01

In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a noise signal varies considerably with the shape of the frequency spectrum of the noise signal. In particular the bandwidth of the spectrum has a large effect on the loudness level, due to the effect of critical bands in the human hearing system. The low-frequency content of the spectrum also has an effect on the loudness level. In this note the relation between loudness level and A-weighted sound level is analyzed for various environmental noise spectra, including spectra of traffic noise, aircraft noise, and industrial noise. From loudness levels calculated for these environmental noise spectra, diagrams are constructed that show the relation between loudness level, A-weighted sound level, and shape of the spectrum. The diagrams show that the upper limits of the loudness level for broadband environmental noise spectra are about 20 to 40 phon higher than the lower limits for narrowband spectra, which correspond to the loudness levels of pure tones. The diagrams are useful for assessing limitations and potential improvements of environmental noise control methods and policy based on A-weighted sound levels.

Validation of the Predicted Circumferential and Radial Mode Sound Power Levels in the Inlet and Exhaust Ducts of a Fan Ingesting Distorted Inflow

NASA Technical Reports Server (NTRS)

Koch, L. Danielle

2012-01-01

Fan inflow distortion tone noise has been studied computationally and experimentally. Data from two experiments in the NASA Glenn Advanced Noise Control Fan rig have been used to validate acoustic predictions. The inflow to the fan was distorted by cylindrical rods inserted radially into the inlet duct one rotor chord length upstream of the fan. The rods were arranged in both symmetric and asymmetric circumferential patterns. In-duct and farfield sound pressure level measurements were recorded. It was discovered that for positive circumferential modes, measured circumferential mode sound power levels in the exhaust duct were greater than those in the inlet duct and for negative circumferential modes, measured total circumferential mode sound power levels in the exhaust were less than those in the inlet. Predicted trends in overall sound power level were proven to be useful in identifying circumferentially asymmetric distortion patterns that reduce overall inlet distortion tone noise, as compared to symmetric arrangements of rods. Detailed comparisons between the measured and predicted radial mode sound power in the inlet and exhaust duct indicate limitations of the theory.

Hearing with an atympanic ear: good vibration and poor sound-pressure detection in the royal python, Python regius.

PubMed

Christensen, Christian Bech; Christensen-Dalsgaard, Jakob; Brandt, Christian; Madsen, Peter Teglberg

2012-01-15

Snakes lack both an outer ear and a tympanic middle ear, which in most tetrapods provide impedance matching between the air and inner ear fluids and hence improve pressure hearing in air. Snakes would therefore be expected to have very poor pressure hearing and generally be insensitive to airborne sound, whereas the connection of the middle ear bone to the jaw bones in snakes should confer acute sensitivity to substrate vibrations. Some studies have nevertheless claimed that snakes are quite sensitive to both vibration and sound pressure. Here we test the two hypotheses that: (1) snakes are sensitive to sound pressure and (2) snakes are sensitive to vibrations, but cannot hear the sound pressure per se. Vibration and sound-pressure sensitivities were quantified by measuring brainstem evoked potentials in 11 royal pythons, Python regius. Vibrograms and audiograms showed greatest sensitivity at low frequencies of 80-160 Hz, with sensitivities of -54 dB re. 1 m s(-2) and 78 dB re. 20 μPa, respectively. To investigate whether pythons detect sound pressure or sound-induced head vibrations, we measured the sound-induced head vibrations in three dimensions when snakes were exposed to sound pressure at threshold levels. In general, head vibrations induced by threshold-level sound pressure were equal to or greater than those induced by threshold-level vibrations, and therefore sound-pressure sensitivity can be explained by sound-induced head vibration. From this we conclude that pythons, and possibly all snakes, lost effective pressure hearing with the complete reduction of a functional outer and middle ear, but have an acute vibration sensitivity that may be used for communication and detection of predators and prey.

Ultrasound visual feedback treatment and practice variability for residual speech sound errors

PubMed Central

Preston, Jonathan L.; McCabe, Patricia; Rivera-Campos, Ahmed; Whittle, Jessica L.; Landry, Erik; Maas, Edwin

2014-01-01

Purpose The goals were to (1) test the efficacy of a motor-learning based treatment that includes ultrasound visual feedback for individuals with residual speech sound errors, and (2) explore whether the addition of prosodic cueing facilitates speech sound learning. Method A multiple baseline single subject design was used, replicated across 8 participants. For each participant, one sound context was treated with ultrasound plus prosodic cueing for 7 sessions, and another sound context was treated with ultrasound but without prosodic cueing for 7 sessions. Sessions included ultrasound visual feedback as well as non-ultrasound treatment. Word-level probes assessing untreated words were used to evaluate retention and generalization. Results For most participants, increases in accuracy of target sound contexts at the word level were observed with the treatment program regardless of whether prosodic cueing was included. Generalization between onset singletons and clusters was observed, as well as generalization to sentence-level accuracy. There was evidence of retention during post-treatment probes, including at a two-month follow-up. Conclusions A motor-based treatment program that includes ultrasound visual feedback can facilitate learning of speech sounds in individuals with residual speech sound errors. PMID:25087938

Opponent Coding of Sound Location (Azimuth) in Planum Temporale is Robust to Sound-Level Variations

PubMed Central

Derey, Kiki; Valente, Giancarlo; de Gelder, Beatrice; Formisano, Elia

2016-01-01

Coding of sound location in auditory cortex (AC) is only partially understood. Recent electrophysiological research suggests that neurons in mammalian auditory cortex are characterized by broad spatial tuning and a preference for the contralateral hemifield, that is, a nonuniform sampling of sound azimuth. Additionally, spatial selectivity decreases with increasing sound intensity. To accommodate these findings, it has been proposed that sound location is encoded by the integrated activity of neuronal populations with opposite hemifield tuning (“opponent channel model”). In this study, we investigated the validity of such a model in human AC with functional magnetic resonance imaging (fMRI) and a phase-encoding paradigm employing binaural stimuli recorded individually for each participant. In all subjects, we observed preferential fMRI responses to contralateral azimuth positions. Additionally, in most AC locations, spatial tuning was broad and not level invariant. We derived an opponent channel model of the fMRI responses by subtracting the activity of contralaterally tuned regions in bilateral planum temporale. This resulted in accurate decoding of sound azimuth location, which was unaffected by changes in sound level. Our data thus support opponent channel coding as a neural mechanism for representing acoustic azimuth in human AC. PMID:26545618

Concorde noise-induced building vibrations for Sully Plantation, Chantilly, Virginia

NASA Technical Reports Server (NTRS)

Mayes, W. H.; Scholl, H. F.; Stephens, D. G.; Holliday, B. G.; Deloach, R.; Holmes, H. K.; Lewis, R. B.; Lynch, J. W.

1976-01-01

A study to assess the noise-induced building vibrations associated with Concorde operations is presented. The approach is to record the levels of induced vibrations and associated indoor/outdoor noise levels in selected homes, historic and other buildings near Dulles and Kennedy International Airports. Presented is a small, representative sample of data recorded at Sully Plantation, Chantilly, Virginia during the period of May 20 through May 28, 1976. Recorded data provide relationships between the vibration levels of walls, floors, windows, and the noise associated with Concorde operations (2 landings and 3 takeoffs), other aircraft, nonaircraft sources, and normal household activities. Results suggest that building vibrations resulting from aircraft operations were proportional to the overall sound pressure levels and relatively insensitive to spectral differences associated with the different types of aircraft. Furthermore, the maximum levels of vibratory response resulting from Concorde operations were higher than those associated with conventional aircraft. The vibrations of nonaircraft events were observed in some cases to exceed the levels resulting from aircraft operations. These nonaircraft events are currently being analyzed in greater detail.

Vital Signs Rate Meter.

DTIC Science & Technology

1987-09-01

stethoscope . Auscultation in respiratory medicine, however, has advanced slowly since Laennec established auscultation of lung sounds as a means of... stethoscope and the ear have limitations in their use as instruments for the evaluation of respiratory sounds. Respiratory sounds have a wide spectrum...Amplification, Rectification and Level-shft ing Stage ... 11 Respiratory Sound Circuitry ....... .................. ... 11 Sound Sensor

Sound recordings of road maintenance equipment on the Lincoln National Forest, New Mexico

Treesearch

D. K. Delaney; T. G. Grubb

2004-01-01

The purpose of this pilot study was to record, characterize, and quantify road maintenance activity in Mexican spotted owl (Strix occidentalis lucida) habitat to gauge potential sound level exposure for owls during road maintenance activities. We measured sound levels from three different types of road maintenance equipment (rock crusherlloader,...

Speech perception task with pseudowords.

PubMed

Appezzato, Mariana Martins; Hackerott, Maria Mercedes Saraiva; Avila, Clara Regina Brandão de

2018-01-01

Purpose Prepare a list of pseudowords in Brazilian Portuguese to assess the auditory discrimination ability of schoolchildren and investigate the internal consistency of test items and the effect of school grade on discrimination performance. Methods Study participants were 60 schoolchildren (60% female) enrolled in the 3rd (n=14), 4th (n=24) and 5th (n=22) grades of an elementary school in the city of Sao Paulo, Brazil, aged between eight years and two months and 11 years and eight months (99 to 136 months; mean=120.05; SD=10.26), with average school performance score of 7.21 (minimum 5.0; maximum 10; SD=1.23). Forty-eight minimal pairs of Brazilian Portuguese pseudowords distinguished by a single phoneme were prepared. The participants' responses (whether the elements of the pairs were the same or different) were noted and analyzed. The data were analyzed using the Cronbach's Alpha Coefficient, Spearman's Correlation Coefficient, and Bonferroni Post-hoc Test at significance level of 0.05. Results Internal consistency analysis indicated the deletion of 20 pairs. The 28 items with results showed good internal consistency (α=0.84). The maximum and minimum scores of correct discrimination responses were 34 and 16, respectively (mean=30.79; SD=3.68). No correlation was observed between age, school performance, and discrimination performance, and no difference between school grades was found. Conclusion Most of the items proposed for assessing the auditory discrimination of speech sounds showed good internal consistency in relation to the task. Age and school grade did not improve the auditory discrimination of speech sounds.

Underwater passive acoustic localization of Pacific walruses in the northeastern Chukchi Sea.

PubMed

Rideout, Brendan P; Dosso, Stan E; Hannay, David E

2013-09-01

This paper develops and applies a linearized Bayesian localization algorithm based on acoustic arrival times of marine mammal vocalizations at spatially-separated receivers which provides three-dimensional (3D) location estimates with rigorous uncertainty analysis. To properly account for uncertainty in receiver parameters (3D hydrophone locations and synchronization times) and environmental parameters (water depth and sound-speed correction), these quantities are treated as unknowns constrained by prior estimates and prior uncertainties. Unknown scaling factors on both the prior and arrival-time uncertainties are estimated by minimizing Akaike's Bayesian information criterion (a maximum entropy condition). Maximum a posteriori estimates for sound source locations and times, receiver parameters, and environmental parameters are calculated simultaneously using measurements of arrival times for direct and interface-reflected acoustic paths. Posterior uncertainties for all unknowns incorporate both arrival time and prior uncertainties. Monte Carlo simulation results demonstrate that, for the cases considered here, linearization errors are small and the lack of an accurate sound-speed profile does not cause significant biases in the estimated locations. A sequence of Pacific walrus vocalizations, recorded in the Chukchi Sea northwest of Alaska, is localized using this technique, yielding a track estimate and uncertainties with an estimated speed comparable to normal walrus swim speeds.

7 CFR 1980.472 - Protective advances.

Code of Federal Regulations, 2013 CFR

2013-01-01

... lieu of additional loans, in particular, working capital loans. Protective advances are advances made... importance, but preserving collateral for maximum recovery is of vital importance. Elements which should... advances, sound judgment must be exercised in determining that the additional funds advanced will actually...

7 CFR 1980.472 - Protective advances.

Code of Federal Regulations, 2012 CFR

2012-01-01

... lieu of additional loans, in particular, working capital loans. Protective advances are advances made... importance, but preserving collateral for maximum recovery is of vital importance. Elements which should... advances, sound judgment must be exercised in determining that the additional funds advanced will actually...

75 FR 23798 - Environmental Assessment Prepared for Proposed Cape Wind Energy Project in Nantucket Sound...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-04

... calls for 130, 3.6 megawatt (MW) wind turbine generators, each with a maximum blade height of 440 feet... transmission cables, which would run through Massachusetts' territory to shore. For reference, the northernmost...

75 FR 10500 - Environmental Assessment Prepared for Proposed Cape Wind Energy Project in Nantucket Sound, MA

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-08

... calls for 130, 3.6 megawatt (MW) wind turbine generators, each with a maximum blade height of 440 feet... in Federal waters, aside from transmission cables running through Massachusetts waters ashore. For...

Design parameters of stainless steel plates for maximizing high frequency ultrasound wave transmission.

PubMed

Michaud, Mark; Leong, Thomas; Swiergon, Piotr; Juliano, Pablo; Knoerzer, Kai

2015-09-01

This work validated, in a higher frequency range, the theoretical predictions made by Boyle around 1930, which state that the optimal transmission of sound pressure through a metal plate occurs when the plate thickness equals a multiple of half the wavelength of the sound wave. Several reactor design parameters influencing the transmission of high frequency ultrasonic waves through a stainless steel plate were examined. The transmission properties of steel plates of various thicknesses (1-7 mm) were studied for frequencies ranging from 400 kHz to 2 MHz and at different distances between plates and transducers. It was shown that transmission of sound pressure through a steel plate showed high dependence of the thickness of the plate to the frequency of the sound wave (thickness ratio). Maximum sound pressure transmission of ∼ 60% of the incident pressure was observed when the ratio of the plate thickness to the applied frequency was a multiple of a half wavelength (2 MHz, 6mm stainless steel plate). In contrast, minimal sound pressure transmission (∼ 10-20%) was measured for thickness ratios that were not a multiple of a half wavelength. Furthermore, the attenuation of the sound pressure in the transmission region was also investigated. As expected, it was confirmed that higher frequencies have more pronounced sound pressure attenuation than lower frequencies. The spatial distribution of the sound pressure transmitted through the plate characterized by sonochemiluminescence measurements using luminol emission, supports the validity of the pressure measurements in this study. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterising the ambient sound environment for infants in intensive care wards.

PubMed

Shoemark, Helen; Harcourt, Edward; Arnup, Sarah J; Hunt, Rod W

2016-04-01

The purpose of this study is to characterise ambient sound levels of paediatric and neonatal intensive care units in an old and new hospital according to current standards. The sound environment was surveyed for 24-h data collection periods (n = 80) in the Neonatal and Paediatric Intensive Care Units (NICUs and PICUs) and Special Care Nursery of the old and new Royal Children's Hospital Melbourne. The ambient sound environment was characterised as the proportion of time the ongoing ambient sound met standard benchmarks, the mean 5-s sound levels and the number and duration of noise events. In the old hospital, none of the data collection periods in the NICU and PICU met the standard benchmark for ongoing ambient sound, while only 5 of the 22 data collection periods in the new hospital met the recommended level. There was no change in proportion of time at recommended Leq between the old and the new Special Care Nursery. There was strong evidence for a difference in the mean number of events >65 dBA (Lmax ) in the old and new hospital (rate ratio = 0.82, 95% confidence interval: 0.73 to 0.92, P = 0.001). The NICU and PICU were above 50 dBA in 75% of all data collection periods, with ventilatory equipment associated with higher ongoing ambient sound levels. The ongoing ambient sound suggests that the background sound environment of the new hospital is not different to the old hospital. However, there may be a reduction in the number of noise events. © 2016 The Authors Journal of Paediatrics and Child Health © 2016 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

Contralateral routing of signals disrupts monaural level and spectral cues to sound localisation on the horizontal plane.

PubMed

Pedley, Adam J; Kitterick, Pádraig T

2017-09-01

Contra-lateral routing of signals (CROS) devices re-route sound between the deaf and hearing ears of unilaterally-deaf individuals. This rerouting would be expected to disrupt access to monaural level cues that can support monaural localisation in the horizontal plane. However, such a detrimental effect has not been confirmed by clinical studies of CROS use. The present study aimed to exercise strict experimental control over the availability of monaural cues to localisation in the horizontal plane and the fitting of the CROS device to assess whether signal routing can impair the ability to locate sources of sound and, if so, whether CROS selectively disrupts monaural level or spectral cues to horizontal location, or both. Unilateral deafness and CROS device use were simulated in twelve normal hearing participants. Monaural recordings of broadband white noise presented from three spatial locations (-60°, 0°, and +60°) were made in the ear canal of a model listener using a probe microphone with and without a CROS device. The recordings were presented to participants via an insert earphone placed in their right ear. The recordings were processed to disrupt either monaural level or spectral cues to horizontal sound location by roving presentation level or the energy across adjacent frequency bands, respectively. Localisation ability was assessed using a three-alternative forced-choice spatial discrimination task. Participants localised above chance levels in all conditions. Spatial discrimination accuracy was poorer when participants only had access to monaural spectral cues compared to when monaural level cues were available. CROS use impaired localisation significantly regardless of whether level or spectral cues were available. For both cues, signal re-routing had a detrimental effect on the ability to localise sounds originating from the side of the deaf ear (-60°). CROS use also impaired the ability to use level cues to localise sounds originating from straight ahead (0°). The re-routing of sounds can restrict access to the monaural cues that provide a basis for determining sound location in the horizontal plane. Perhaps encouragingly, the results suggest that both monaural level and spectral cues may not be disrupted entirely by signal re-routing and that it may still be possible to reliably identify sounds originating on the hearing side. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Influences of age, gender, and parents' educational level in knowledge, behavior and preferences regarding noise, from childhood to adolescence.

PubMed

Knobel, Keila Alessandra Baraldi; Lima, Maria Cecília Marconi Pinheiro

2014-01-01

Exposure to loud sound during leisure activities for long periods of time is an important area to implement preventive health education, especially among young people. The aim was to identify the relations among awareness about the damaging effects of loud levels of sounds, previous exposures do loud sounds, preferences-related to sound levels and knowledge about hearing protection with age, gender, and their parent's educational level among children. Prospective cross-sectional. Seven hundred and forty students (5-16 years old) and 610 parents participated in the study. Chi-square test, Fisher exact test and linear regression. About 86.5% of the children consider that loud sounds damage the ears and 53.7% dislike noisy places. Children were previously exposed to parties and concerts with loud music, Mardi Gras, firecrackers and loud music at home or in the car and loud music with earphones. About 18.4% of the younger children could select the volume of the music, versus 65.3% of the older ones. Children have poor information about hearing protection and do not have hearing protection device. Knowledge about the risks related to exposures to loud sounds and about strategies to protect their hearing increases with age, but preference for loud sounds and exposures to it increases too. Gender and parents' instructional level have little influence on the studied variables. Many of the children's recreational activities are noisy. It is possible that the tendency of increasing preference for loud sounds with age might be a result of a learned behavior.

Emphasis of spatial cues in the temporal fine structure during the rising segments of amplitude-modulated sounds II: single-neuron recordings

PubMed Central

Marquardt, Torsten; Stange, Annette; Pecka, Michael; Grothe, Benedikt; McAlpine, David

2014-01-01

Recently, with the use of an amplitude-modulated binaural beat (AMBB), in which sound amplitude and interaural-phase difference (IPD) were modulated with a fixed mutual relationship (Dietz et al. 2013b), we demonstrated that the human auditory system uses interaural timing differences in the temporal fine structure of modulated sounds only during the rising portion of each modulation cycle. However, the degree to which peripheral or central mechanisms contribute to the observed strong dominance of the rising slope remains to be determined. Here, by recording responses of single neurons in the medial superior olive (MSO) of anesthetized gerbils and in the inferior colliculus (IC) of anesthetized guinea pigs to AMBBs, we report a correlation between the position within the amplitude-modulation (AM) cycle generating the maximum response rate and the position at which the instantaneous IPD dominates the total neural response. The IPD during the rising segment dominates the total response in 78% of MSO neurons and 69% of IC neurons, with responses of the remaining neurons predominantly coding the IPD around the modulation maximum. The observed diversity of dominance regions within the AM cycle, especially in the IC, and its comparison with the human behavioral data suggest that only the subpopulation of neurons with rising slope dominance codes the sound-source location in complex listening conditions. A comparison of two models to account for the data suggests that emphasis on IPDs during the rising slope of the AM cycle depends on adaptation processes occurring before binaural interaction. PMID:24554782

Tinnitus is associated with reduced sound level tolerance in adolescents with normal audiograms and otoacoustic emissions

PubMed Central

Sanchez, Tanit Ganz; Moraes, Fernanda; Casseb, Juliana; Cota, Jaci; Freire, Katya; Roberts, Larry E.

2016-01-01

Recent neuroscience research suggests that tinnitus may reflect synaptic loss in the cochlea that does not express in the audiogram but leads to neural changes in auditory pathways that reduce sound level tolerance (SLT). Adolescents (N = 170) completed a questionnaire addressing their prior experience with tinnitus, potentially risky listening habits, and sensitivity to ordinary sounds, followed by psychoacoustic measurements in a sound booth. Among all adolescents 54.7% reported by questionnaire that they had previously experienced tinnitus, while 28.8% heard tinnitus in the booth. Psychoacoustic properties of tinnitus measured in the sound booth corresponded with those of chronic adult tinnitus sufferers. Neither hearing thresholds (≤15 dB HL to 16 kHz) nor otoacoustic emissions discriminated between adolescents reporting or not reporting tinnitus in the sound booth, but loudness discomfort levels (a psychoacoustic measure of SLT) did so, averaging 11.3 dB lower in adolescents experiencing tinnitus in the acoustic chamber. Although risky listening habits were near universal, the teenagers experiencing tinnitus and reduced SLT tended to be more protective of their hearing. Tinnitus and reduced SLT could be early indications of a vulnerability to hidden synaptic injury that is prevalent among adolescents and expressed following exposure to high level environmental sounds. PMID:27265722

Estimation of multiple sound sources with data and model uncertainties using the EM and evidential EM algorithms

NASA Astrophysics Data System (ADS)

Wang, Xun; Quost, Benjamin; Chazot, Jean-Daniel; Antoni, Jérôme

2016-01-01

This paper considers the problem of identifying multiple sound sources from acoustical measurements obtained by an array of microphones. The problem is solved via maximum likelihood. In particular, an expectation-maximization (EM) approach is used to estimate the sound source locations and strengths, the pressure measured by a microphone being interpreted as a mixture of latent signals emitted by the sources. This work also considers two kinds of uncertainties pervading the sound propagation and measurement process: uncertain microphone locations and uncertain wavenumber. These uncertainties are transposed to the data in the belief functions framework. Then, the source locations and strengths can be estimated using a variant of the EM algorithm, known as the Evidential EM (E2M) algorithm. Eventually, both simulation and real experiments are shown to illustrate the advantage of using the EM in the case without uncertainty and the E2M in the case of uncertain measurement.

Matched Behavioral and Neural Adaptations for Low Sound Level Echolocation in a Gleaning Bat, Antrozous pallidus.

PubMed

Measor, Kevin R; Leavell, Brian C; Brewton, Dustin H; Rumschlag, Jeffrey; Barber, Jesse R; Razak, Khaleel A

2017-01-01

In active sensing, animals make motor adjustments to match sensory inputs to specialized neural circuitry. Here, we describe an active sensing system for sound level processing. The pallid bat uses downward frequency-modulated (FM) sweeps as echolocation calls for general orientation and obstacle avoidance. The bat's auditory cortex contains a region selective for these FM sweeps (FM sweep-selective region, FMSR). We show that the vast majority of FMSR neurons are sensitive and strongly selective for relatively low levels (30-60 dB SPL). Behavioral testing shows that when a flying bat approaches a target, it reduces output call levels to keep echo levels between ∼30 and 55 dB SPL. Thus, the pallid bat behaviorally matches echo levels to an optimized neural representation of sound levels. FMSR neurons are more selective for sound levels of FM sweeps than tones, suggesting that across-frequency integration enhances level tuning. Level-dependent timing of high-frequency sideband inhibition in the receptive field shapes increased level selectivity for FM sweeps. Together with previous studies, these data indicate that the same receptive field properties shape multiple filters (sweep direction, rate, and level) for FM sweeps, a sound common in multiple vocalizations, including human speech. The matched behavioral and neural adaptations for low-intensity echolocation in the pallid bat will facilitate foraging with reduced probability of acoustic detection by prey.

Matched Behavioral and Neural Adaptations for Low Sound Level Echolocation in a Gleaning Bat, Antrozous pallidus

PubMed Central

Measor, Kevin R.; Leavell, Brian C.; Brewton, Dustin H.; Rumschlag, Jeffrey; Barber, Jesse R.

2017-01-01

Abstract In active sensing, animals make motor adjustments to match sensory inputs to specialized neural circuitry. Here, we describe an active sensing system for sound level processing. The pallid bat uses downward frequency-modulated (FM) sweeps as echolocation calls for general orientation and obstacle avoidance. The bat’s auditory cortex contains a region selective for these FM sweeps (FM sweep-selective region, FMSR). We show that the vast majority of FMSR neurons are sensitive and strongly selective for relatively low levels (30-60 dB SPL). Behavioral testing shows that when a flying bat approaches a target, it reduces output call levels to keep echo levels between ∼30 and 55 dB SPL. Thus, the pallid bat behaviorally matches echo levels to an optimized neural representation of sound levels. FMSR neurons are more selective for sound levels of FM sweeps than tones, suggesting that across-frequency integration enhances level tuning. Level-dependent timing of high-frequency sideband inhibition in the receptive field shapes increased level selectivity for FM sweeps. Together with previous studies, these data indicate that the same receptive field properties shape multiple filters (sweep direction, rate, and level) for FM sweeps, a sound common in multiple vocalizations, including human speech. The matched behavioral and neural adaptations for low-intensity echolocation in the pallid bat will facilitate foraging with reduced probability of acoustic detection by prey. PMID:28275715

Determination of water quality, toxicity and estrogenic activity in a nearshore marine environment in Rio de Janeiro, Southeastern Brazil.

PubMed

do Nascimento, Marilia Teresa Lima; Santos, Ana Dalva de Oliveira; Felix, Louise Cruz; Gomes, Giselle; de Oliveira E Sá, Mariana; da Cunha, Danieli Lima; Vieira, Natividade; Hauser-Davis, Rachel Ann; Baptista Neto, José Antonio; Bila, Daniele Maia

2018-03-01

Endocrine disrupting compounds (EDCs) can be found in domestic sewage, wastewater treatment plant effluents, natural water, rivers, lakes and in the marine environment. Jurujuba Sound, located in the state of Rio de Janeiro, Southeastern Brazil, receives untreated sewage into its waters, one the main sources of aquatic contamination in this area. In this context, the aim of the present study was to evaluate the estrogenic potential of water sampled from different depths and from areas with differential contamination levels throughout Jurujuba Sound. Water quality was evaluated and acute toxicity assays using Allviibrio fischeri were conducted, while estrogenic activity of the water samples was determined by a Yeast Estrogen Screening assay (YES). Water quality was mostly within the limits established for marine waters by the Brazilian legislation, with only DOC and ammoniacal nitrogen levels above the maximum permissible limits. No acute toxicity effects were observed in the Allivibrio fisheri assay. The YES assay detected moderate estrogenic activity in bottom water samples from 3 sampling stations, ranging from 0.5 to 3.2ngL -1 , as well as in one surface water sample. Estrogenic activity was most frequently observed in samples from the bottom of the water column, indicating adsorption of estrogenic compounds to the sediment. Copyright © 2017 Elsevier Inc. All rights reserved.

Characteristics of the swallowing sounds recorded in the ear, nose and on trachea.

PubMed

Sarraf-Shirazi, Samaneh; Baril, Jonathan-F; Moussavi, Zahra

2012-08-01

The various malfunctions and difficulties of the swallowing mechanism necessitate various diagnostic techniques to address those problems. Swallowing sounds recorded from the trachea have been suggested as a noninvasive method of swallowing assessment. However, acquiring signals from the trachea can be difficult for those with loose skin. The objective of this pilot study was to explore the viability of using the ear and nose as alternative recording locations for recording swallowing sounds. We recorded the swallowing and breathing sounds of five healthy young individuals from the ear, nose and trachea, simultaneously. We computed time-frequency features and compared them for the different locations of recording. The features included the peak and the maximum frequencies of the power spectrum density, average power at different frequency bands and the wavelet coefficients. The average power calculated over the 4 octave bands between 150 and 2,400 Hz showed a consistent trend with less than 20 dB difference for the breath sounds of all the recording locations. Thus, analyzing breath sounds recorded from the ear and nose for the purpose of aspiration detection would give similar results to those from tracheal recordings; thus, ear and nose recording may be a viable alternative when tracheal recording is not possible.

Sound Levels in East Texas Schools.

ERIC Educational Resources Information Center

Turner, Aaron Lynn

A survey of sound levels was taken in several Texas schools to determine the amount of noise and sound present by size of class, type of activity, location of building, and the presence of air conditioning and large amounts of glass. The data indicate that class size and relative amounts of glass have no significant bearing on the production of…

The influence of the level formants on the perception of synthetic vowel sounds

NASA Astrophysics Data System (ADS)

Kubzdela, Henryk; Owsianny, Mariuz

A computer model of a generator of periodic complex sounds simulating consonants was developed. The system makes possible independent regulation of the level of each of the formants and instant generation of the sound. A trapezoid approximates the curve of the spectrum within the range of the formant. In using this model, each person in a group of six listeners experimentally selected synthesis parameters for six sounds that to him seemed optimal approximations of Polish consonants. From these, another six sounds were selected that were identified by a majority of the six persons and several additional listeners as being best qualified to serve as prototypes of Polish consonants. These prototypes were then used to randomly create sounds with various combinations at the level of the second and third formant and these were presented to seven listeners for identification. The results of the identifications are presented in table form in three variants and are described from the point of view of the requirements of automatic recognition of consonants in continuous speech.

Mitigation of Sri Lanka Island Effects in Colombo Sounding Data during DYNAMO

NASA Astrophysics Data System (ADS)

Ciesielski, P. E.; Johnson, R. H.; Yoneyama, K.

2013-12-01

During the Dynamics of the MJO (DYNAMO) field campaign, upper-air soundings were launched at Colombo, Sri Lanka as part of the enhanced northern sounding array (NSA) of the experiment. The Colombo soundings were affected at low-levels by diurnal heating of this large island and by flow blocking due to elevated terrain to the east of the Colombo site. Because of the large spacing between sounding sites, these small-scale effects are aliased onto the larger scale impacting analyses and atmospheric budgets over the DYNAMO NSA. To mitigate these local island effects on the large-scale budgets, a procedure was designed which uses ECMWF-analyzed fields in the vicinity of Sri Lanka to estimate open-ocean conditions (i.e, as if this island were not present). These 'unperturbed' ECMWF fields at low-levels are then merged with observed Colombo soundings. This procedure effectively mutes the blocking effects and large diurnal cycle observed in the low-level Colombo fields. In westerly flow regimes, adjusted Colombo winds increase the low-level westerlies by 2-3 m/s with a similar increase of the low-level easterlies in easterly flow regimes. In general, over the NSA the impact of the adjusted Colombo winds results in more low-level divergence (convergence), more mid-level subsidence (rising motion) and reduced (increased) rainfall during the westerly (easterly) wind regimes. In comparison to independent TRMM rainfall estimates, both the mean budget-derived rainfall and its temporal correlation are improved by using the adjusted Colombo soundings. In addition, use of the 'unperturbed' fields result in a more realistic moisture budget analyses, both in its diurnal cycle and during the build-up phase of the November MJO when a gradual deepening of apparent drying was observed. Overall, use of the adjusted Colombo soundings appears to have a beneficial impact on the NSA analyses and budgets.

Why Do People Like Loud Sound? A Qualitative Study

PubMed Central

Welch, David; Fremaux, Guy

2017-01-01

Many people choose to expose themselves to potentially dangerous sounds such as loud music, either via speakers, personal audio systems, or at clubs. The Conditioning, Adaptation and Acculturation to Loud Music (CAALM) Model has proposed a theoretical basis for this behaviour. To compare the model to data, we interviewed a group of people who were either regular nightclub-goers or who controlled the sound levels in nightclubs (bar managers, musicians, DJs, and sound engineers) about loud sound. Results showed four main themes relating to the enjoyment of loud sound: arousal/excitement, facilitation of socialisation, masking of both external sound and unwanted thoughts, and an emphasis and enhancement of personal identity. Furthermore, an interesting incidental finding was that sound levels appeared to increase gradually over the course of the evening until they plateaued at approximately 97 dBA Leq around midnight. Consideration of the data generated by the analysis revealed a complex of influential factors that support people in wanting exposure to loud sound. Findings were considered in terms of the CAALM Model and could be explained in terms of its principles. From a health promotion perspective, the Social Ecological Model was applied to consider how the themes identified might influence behaviour. They were shown to influence people on multiple levels, providing a powerful system which health promotion approaches struggle to address. PMID:28800097

Metal Sounds Stiffer than Drums for Ears, but Not Always for Hands: Low-Level Auditory Features Affect Multisensory Stiffness Perception More than High-Level Categorical Information

PubMed Central

Liu, Juan; Ando, Hiroshi

2016-01-01

Most real-world events stimulate multiple sensory modalities simultaneously. Usually, the stiffness of an object is perceived haptically. However, auditory signals also contain stiffness-related information, and people can form impressions of stiffness from the different impact sounds of metal, wood, or glass. To understand whether there is any interaction between auditory and haptic stiffness perception, and if so, whether the inferred material category is the most relevant auditory information, we conducted experiments using a force-feedback device and the modal synthesis method to present haptic stimuli and impact sound in accordance with participants’ actions, and to modulate low-level acoustic parameters, i.e., frequency and damping, without changing the inferred material categories of sound sources. We found that metal sounds consistently induced an impression of stiffer surfaces than did drum sounds in the audio-only condition, but participants haptically perceived surfaces with modulated metal sounds as significantly softer than the same surfaces with modulated drum sounds, which directly opposes the impression induced by these sounds alone. This result indicates that, although the inferred material category is strongly associated with audio-only stiffness perception, low-level acoustic parameters, especially damping, are more tightly integrated with haptic signals than the material category is. Frequency played an important role in both audio-only and audio-haptic conditions. Our study provides evidence that auditory information influences stiffness perception differently in unisensory and multisensory tasks. Furthermore, the data demonstrated that sounds with higher frequency and/or shorter decay time tended to be judged as stiffer, and contact sounds of stiff objects had no effect on the haptic perception of soft surfaces. We argue that the intrinsic physical relationship between object stiffness and acoustic parameters may be applied as prior knowledge to achieve robust estimation of stiffness in multisensory perception. PMID:27902718

J-85 jet engine noise measured in the ONERA S1 wind tunnel and extrapolated to far field

NASA Technical Reports Server (NTRS)

Soderman, Paul T.; Julienne, Alain; Atencio, Adolph, Jr.

1991-01-01

Noise from a J-85 turbojet with a conical, convergent nozzle was measured in simulated flight in the ONERA S1 Wind Tunnel. Data are presented for several flight speeds up to 130 m/sec and for radiation angles of 40 to 160 degrees relative to the upstream direction. The jet was operated with subsonic and sonic exhaust speeds. A moving microphone on a 2 m sideline was used to survey the radiated sound field in the acoustically treated, closed test section. The data were extrapolated to a 122 m sideline by means of a multiple-sideline source-location method, which was used to identify the acoustic source regions, directivity patterns, and near field effects. The source-location method is described along with its advantages and disadvantages. Results indicate that the effects of simulated flight on J-85 noise are significant. At the maximum forward speed of 130 m/sec, the peak overall sound levels in the aft quadrant were attentuated approximately 10 dB relative to sound levels of the engine operated statically. As expected, the simulated flight and static data tended to merge in the forward quadrant as the radiation angle approached 40 degrees. There is evidence that internal engine or shock noise was important in the forward quadrant. The data are compared with published predictions for flight effects on pure jet noise and internal engine noise. A new empirical prediction is presented that relates the variation of internally generated engine noise or broadband shock noise to forward speed. Measured near field noise extrapolated to far field agrees reasonably well with data from similar engines tested statically outdoors, in flyover, in a wind tunnel, and on the Bertin Aerotrain. Anomalies in the results for the forward quadrant and for angles above 140 degrees are discussed. The multiple-sideline method proved to be cumbersome in this application, and it did not resolve all of the uncertainties associated with measurements of jet noise close to the jet. The simulation was complicated by wind-tunnel background noise and the propagation of low frequency sound around the circuit.

Lack of behavioural responses of humpback whales (Megaptera novaeangliae) indicate limited effectiveness of sonar mitigation

PubMed Central

Kvadsheim, Petter H.; Lam, Frans-Peter A.; von Benda-Beckmann, Alexander M.; Sivle, Lise D.; Visser, Fleur; Curé, Charlotte; Tyack, Peter L.; Miller, Patrick J. O.

2017-01-01

ABSTRACT Exposure to underwater sound can cause permanent hearing loss and other physiological effects in marine animals. To reduce this risk, naval sonars are sometimes gradually increased in intensity at the start of transmission (‘ramp-up’). Here, we conducted experiments in which tagged humpback whales were approached with a ship to test whether a sonar operation preceded by ramp-up reduced three risk indicators – maximum sound pressure level (SPLmax), cumulative sound exposure level (SELcum) and minimum source–whale range (Rmin) – compared with a sonar operation not preceded by ramp-up. Whales were subject to one no-sonar control session and either two successive ramp-up sessions (RampUp1, RampUp2) or a ramp-up session (RampUp1) and a full-power session (FullPower). Full-power sessions were conducted only twice; for other whales we used acoustic modelling that assumed transmission of the full-power sequence during their no-sonar control. Averaged over all whales, risk indicators in RampUp1 (n=11) differed significantly from those in FullPower (n=12) by −3.0 dB (SPLmax), −2.0 dB (SELcum) and +168 m (Rmin), but not significantly from those in RampUp2 (n=9). Only five whales in RampUp1, four whales in RampUp2 and none in FullPower or control sessions avoided the sound source. For RampUp1, we found statistically significant differences in risk indicators between whales that avoided the sonar and whales that did not: −4.7 dB (SPLmax), −3.4 dB (SELcum) and +291 m (Rmin). In contrast, for RampUp2, these differences were smaller and not significant. This study suggests that sonar ramp-up has a positive but limited mitigative effect for humpback whales overall, but that ramp-up can reduce the risk of harm more effectively in situations when animals are more responsive and likely to avoid the sonar, e.g. owing to novelty of the stimulus, when they are in the path of an approaching sonar ship. PMID:29141878

Apparent source levels and active communication space of whistles of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in the Pearl River Estuary and Beibu Gulf, China

PubMed Central

Wang, Zhi-Tao; W.L. Au, Whitlow; Rendell, Luke; Wu, Hai-Ping; Wu, Yu-Ping; Liu, Jian-Chang; Duan, Guo-Qin; Cao, Han-Jiang

2016-01-01

Background. Knowledge of species-specific vocalization characteristics and their associated active communication space, the effective range over which a communication signal can be detected by a conspecific, is critical for understanding the impacts of underwater acoustic pollution, as well as other threats. Methods. We used a two-dimensional cross-shaped hydrophone array system to record the whistles of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in shallow-water environments of the Pearl River Estuary (PRE) and Beibu Gulf (BG), China. Using hyperbolic position fixing, which exploits time differences of arrival of a signal between pairs of hydrophone receivers, we obtained source location estimates for whistles with good signal-to-noise ratio (SNR ≥10 dB) and not polluted by other sounds and back-calculated their apparent source levels (ASL). Combining with the masking levels (including simultaneous noise levels, masking tonal threshold, and the Sousa auditory threshold) and the custom made site-specific sound propagation models, we further estimated their active communication space (ACS). Results. Humpback dolphins produced whistles with average root-mean-square ASL of 138.5 ± 6.8 (mean ± standard deviation) and 137.2 ± 7.0 dB re 1 µPa in PRE (N = 33) and BG (N = 209), respectively. We found statistically significant differences in ASLs among different whistle contour types. The mean and maximum ACS of whistles were estimated to be 14.7 ± 2.6 (median ± quartile deviation) and 17.1± 3.5 m in PRE, and 34.2 ± 9.5 and 43.5 ± 12.2 m in BG. Using just the auditory threshold as the masking level produced the mean and maximum ACSat of 24.3 ± 4.8 and 35.7 ± 4.6 m for PRE, and 60.7 ± 18.1 and 74.3 ± 25.3 m for BG. The small ACSs were due to the high ambient noise level. Significant differences in ACSs were also observed among different whistle contour types. Discussion. Besides shedding some light for evaluating appropriate noise exposure levels and information for the regulation of underwater acoustic pollution, these baseline data can also be used for aiding the passive acoustic monitoring of dolphin populations, defining the boundaries of separate groups in a more biologically meaningful way during field surveys, and guiding the appropriate approach distance for local dolphin-watching boats and research boat during focal group following. PMID:26893973

Apparent source levels and active communication space of whistles of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in the Pearl River Estuary and Beibu Gulf, China.

PubMed

Wang, Zhi-Tao; W L Au, Whitlow; Rendell, Luke; Wang, Ke-Xiong; Wu, Hai-Ping; Wu, Yu-Ping; Liu, Jian-Chang; Duan, Guo-Qin; Cao, Han-Jiang; Wang, Ding

2016-01-01

Background. Knowledge of species-specific vocalization characteristics and their associated active communication space, the effective range over which a communication signal can be detected by a conspecific, is critical for understanding the impacts of underwater acoustic pollution, as well as other threats. Methods. We used a two-dimensional cross-shaped hydrophone array system to record the whistles of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in shallow-water environments of the Pearl River Estuary (PRE) and Beibu Gulf (BG), China. Using hyperbolic position fixing, which exploits time differences of arrival of a signal between pairs of hydrophone receivers, we obtained source location estimates for whistles with good signal-to-noise ratio (SNR ≥10 dB) and not polluted by other sounds and back-calculated their apparent source levels (ASL). Combining with the masking levels (including simultaneous noise levels, masking tonal threshold, and the Sousa auditory threshold) and the custom made site-specific sound propagation models, we further estimated their active communication space (ACS). Results. Humpback dolphins produced whistles with average root-mean-square ASL of 138.5 ± 6.8 (mean ± standard deviation) and 137.2 ± 7.0 dB re 1 µPa in PRE (N = 33) and BG (N = 209), respectively. We found statistically significant differences in ASLs among different whistle contour types. The mean and maximum ACS of whistles were estimated to be 14.7 ± 2.6 (median ± quartile deviation) and 17.1± 3.5 m in PRE, and 34.2 ± 9.5 and 43.5 ± 12.2 m in BG. Using just the auditory threshold as the masking level produced the mean and maximum ACSat of 24.3 ± 4.8 and 35.7 ± 4.6 m for PRE, and 60.7 ± 18.1 and 74.3 ± 25.3 m for BG. The small ACSs were due to the high ambient noise level. Significant differences in ACSs were also observed among different whistle contour types. Discussion. Besides shedding some light for evaluating appropriate noise exposure levels and information for the regulation of underwater acoustic pollution, these baseline data can also be used for aiding the passive acoustic monitoring of dolphin populations, defining the boundaries of separate groups in a more biologically meaningful way during field surveys, and guiding the appropriate approach distance for local dolphin-watching boats and research boat during focal group following.

Some insights into the relationship between urban air pollution and noise levels.

PubMed

Kim, Ki-Hyun; Ho, Duy Xuan; Brown, Richard J C; Oh, J-M; Park, Chan Goo; Ryu, In Cheol

2012-05-01

The relationship between noise and air pollution was investigated in eight different districts across Seoul, Korea, between September and November 2010. The noise levels in each district were measured at both roadside and non-roadside locations. It was found that the maximum levels of noise were generally at frequencies of around 1000 Hz. The equivalent noise levels (L(eq)), over all districts, averaged 61.4 ± 7.36 dB which is slightly lower than the noise guidelines set by the World Health Organization (WHO) of 70 dB for industrial, commercial, traffic, and outdoor areas. Comparison of L(eq) levels in each district consistently indicates that noise levels are higher at roadside sites than non-roadside sites. In addition the relative dominance of noise during daytime as compared to nighttime was also apparent. Moreover, the results of an analysis relating sound levels with air pollutant levels indicate strongly that the correlation between these two parameters is the strongest at roadside sites (relative to non-roadside sites) and during nighttime (relative to daytime). The results of our data analysis point to a positive, but complex, correlation between noise levels and air pollution. Copyright © 2012 Elsevier B.V. All rights reserved.

Noise in contemporary neonatal intensive care.

PubMed

Williams, Amber L; van Drongelen, Wim; Lasky, Robert E

2007-05-01

Weekly sound surveys (n = 63) were collected, using 5 s sampling intervals, for two modern neonatal intensive care units (NICUs). Median weekly equivalent sound pressure levels (LEQ) for NICU A ranged from 61 to 63 dB (A weighted), depending on the level of care. NICU B L(EQ) measurements ranged from 55 to 60 dB (A weighted). NICU B was recently built with a focus on sound abatement, explaining much of the difference between the two NICUs. Sound levels exceeded 45 dB (A weighted), recommended by the American Academy of Pediatrics, more than 70% of the time for all levels of care. Hourly L(EQ)s below 50 dB (A weighted) and hourly L10s below 55 dB (A weighted), recommended by the Sound Study Group (SSG) of the National Resource Center, were also exceeded in more than 70% of recorded samples. A third SSG recommendation, that the 1 s L(MAX), should not exceed 70 dB (A weighted), was exceeded relatively infrequently (< 11% of the time). Peak impulse measurements exceeded 90 dB for 6.3% of 5 s samples recorded from NICU A and 2.8% of NICU B samples. Twenty-four h periodicities in sound levels as a function of regular staff activities were apparent, but short-term variability was considerable.

Opponent Coding of Sound Location (Azimuth) in Planum Temporale is Robust to Sound-Level Variations.

PubMed

Derey, Kiki; Valente, Giancarlo; de Gelder, Beatrice; Formisano, Elia

2016-01-01

Coding of sound location in auditory cortex (AC) is only partially understood. Recent electrophysiological research suggests that neurons in mammalian auditory cortex are characterized by broad spatial tuning and a preference for the contralateral hemifield, that is, a nonuniform sampling of sound azimuth. Additionally, spatial selectivity decreases with increasing sound intensity. To accommodate these findings, it has been proposed that sound location is encoded by the integrated activity of neuronal populations with opposite hemifield tuning ("opponent channel model"). In this study, we investigated the validity of such a model in human AC with functional magnetic resonance imaging (fMRI) and a phase-encoding paradigm employing binaural stimuli recorded individually for each participant. In all subjects, we observed preferential fMRI responses to contralateral azimuth positions. Additionally, in most AC locations, spatial tuning was broad and not level invariant. We derived an opponent channel model of the fMRI responses by subtracting the activity of contralaterally tuned regions in bilateral planum temporale. This resulted in accurate decoding of sound azimuth location, which was unaffected by changes in sound level. Our data thus support opponent channel coding as a neural mechanism for representing acoustic azimuth in human AC. © The Author 2015. Published by Oxford University Press.

Detection System of Sound Noise Level (SNL) Based on Condenser Microphone Sensor

NASA Astrophysics Data System (ADS)

Rajagukguk, Juniastel; Eka Sari, Nurdieni

2018-03-01

The research aims to know the noise level by using the Arduino Uno as data processing input from sensors and called as Sound Noise Level (SNL). The working principle of the instrument is as noise detector with the show notifications the noise level on the LCD indicator and in the audiovisual form. Noise detection using the sensor is a condenser microphone and LM 567 as IC op-amps, which are assembled so that it can detect the noise, which sounds are captured by the sensor will turn the tide of sinusoida voice became sine wave energy electricity (altering sinusoida electric current) that is able to responded to complaints by the Arduino Uno. The tool is equipped with a detector consists of a set indicator LED and sound well as the notification from the text on LCD 16*2. Work setting indicators on the condition that, if the measured noise > 75 dB then sound will beep, the red LED will light up indicating the status of the danger. If the measured value on the LCD is higher than 56 dB, sound indicator will be beep and yellow LED will be on indicating noisy. If the noise measured value <55 dB, sound indicator will be quiet indicating peaceful from noisy. From the result of the research can be explained that the SNL is capable to detecting and displaying noise level with a measuring range 50-100 dB and capable to delivering the notification noise in audiovisual.

Finite Element Analysis of the Endodontically-treated Maxillary Premolars restored with Composite Resin along with Glass Fiber Insertion in Various Positions.

PubMed

Navimipour, Elmira Jafari; Firouzmandi, Maryam; Mirhashemi, Fatemeh Sadat

2015-04-01

This study evaluated the effect of three methods of glass fiber insertion on stress distribution pattern and cusp movement of the root-filled maxillary premolars using finite element method (FEM) analysis. A three-dimensional (3 D) FEM model of a sound upper premolar tooth and four models of root-filled upper premolars with mesiocclusodistal (MOD) cavities were molded and restored with: (1) Composite resin only (NF); (2) Composite resin along with a ribbon of glass fiber placed in the occlusal third (OF); (3) Composite resin along with a ribbon of glass fiber placed circumferentially in the cervical third (CF), and (4) Composite resin along with occlusal and circumferential fibers (OCF). A static vertical load was applied to calculate the stress distributions. Structural analysis program by Solidworks were used for FEM analysis. Von-Mises stress values and cusp movements induced by occlusal loading were evaluated. Maximum Von-Mises stress of enamel occurred in sound tooth, followed by NF, CF, OF and OCF. Maximum Von-Mises stress of dentin occurred in sound tooth, followed by OF, OCF, CF and NF. Stress distribution patterns of OF and OCF were similar. Maximum overall stress values were concentrated in NF. Although stress distribution patterns of NF and CF were found as similar, CF showed lower stress values. Palatal cusp movement was more than buccal cusp in all of the models. The results of our study indicated that while the circumferential fiber had little effect on overall stress concentration, it provided a more favorable stress distribution pattern in cervical region. The occlusal fiber reduced the average stress in the entire structure but did not reduce cuspal movement. Incorporating glass fiber in composite restorations may alter the stress state within the structure depending on fiber position.

Major International R and D Ranges and Test Facilities. Summary of Capabilities

DTIC Science & Technology

1990-01-01

with a maximum impulse of firing of large numbers of rounds by a weapon in order to 1500 G and a maximum test item weight of 200 pounds. produce...millimetres may be fired safely, using test item weight of 1,000 pounds. training practice or training practice tracer ammunition. The :ange butts consist of...predictions of coherent sound propagation loss in the ocean. This information is useful in estimating the performance of low-frequency passive sonars

Intermittency ratio: A metric reflecting short-term temporal variations of transportation noise exposure

PubMed Central

Wunderli, Jean Marc; Pieren, Reto; Habermacher, Manuel; Vienneau, Danielle; Cajochen, Christian; Probst-Hensch, Nicole; Röösli, Martin; Brink, Mark

2016-01-01

Most environmental epidemiology studies model health effects of noise by regressing on acoustic exposure metrics that are based on the concept of average energetic dose over longer time periods (i.e. the Leq and related measures). Regarding noise effects on health and wellbeing, average measures often cannot satisfactorily predict annoyance and somatic health effects of noise, particularly sleep disturbances. It has been hypothesized that effects of noise can be better explained when also considering the variation of the level over time and the frequency distribution of event-related acoustic measures, such as for example, the maximum sound pressure level. However, it is unclear how this is best parametrized in a metric that is not correlated with the Leq, but takes into account the frequency distribution of events and their emergence from background. In this paper, a calculation method is presented that produces a metric which reflects the intermittency of road, rail and aircraft noise exposure situations. The metric termed intermittency ratio (IR) expresses the proportion of the acoustical energy contribution in the total energetic dose that is created by individual noise events above a certain threshold. To calculate the metric, it is shown how to estimate the distribution of maximum pass-by levels from information on geometry (distance and angle), traffic flow (number and speed) and single-event pass-by levels per vehicle category. On the basis of noise maps that simultaneously visualize Leq, as well as IR, the differences of both metrics are discussed. PMID:26350982

AVE/VAS 4: 25-mb sounding data

NASA Technical Reports Server (NTRS)

Sienkiewicz, M. E.

1983-01-01

The rawinsonde sounding program is described and tabulated data at 25 mb intervals for the 24 stations and 14 special stations participating in the experiment is presented. Sounding were taken at 3 hr intervals. An additional sounding was taken at the normal synoptic observation time. Some soundings were computed from raw ordinate data, while others were interpolated from significant level data.

Interpolated Sounding and Gridded Sounding Value-Added Products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toto, T.; Jensen, M.

Standard Atmospheric Radiation Measurement (ARM) Climate Research Facility sounding files provide atmospheric state data in one dimension of increasing time and height per sonde launch. Many applications require a quick estimate of the atmospheric state at higher time resolution. The INTERPOLATEDSONDE (i.e., Interpolated Sounding) Value-Added Product (VAP) transforms sounding data into continuous daily files on a fixed time-height grid, at 1-minute time resolution, on 332 levels, from the surface up to a limit of approximately 40 km. The grid extends that high so the full height of soundings can be captured; however, most soundings terminate at an altitude between 25more » and 30 km, above which no data is provided. Between soundings, the VAP linearly interpolates atmospheric state variables in time for each height level. In addition, INTERPOLATEDSONDE provides relative humidity scaled to microwave radiometer (MWR) observations.The INTERPOLATEDSONDE VAP, a continuous time-height grid of relative humidity-corrected sounding data, is intended to provide input to higher-order products, such as the Merged Soundings (MERGESONDE; Troyan 2012) VAP, which extends INTERPOLATEDSONDE by incorporating model data. The INTERPOLATEDSONDE VAP also is used to correct gaseous attenuation of radar reflectivity in products such as the KAZRCOR VAP.« less

Do high sound pressure levels of crowing in roosters necessitate passive mechanisms for protection against self-vocalization?

PubMed

Claes, Raf; Muyshondt, Pieter G G; Dirckx, Joris J J; Aerts, Peter

2018-02-01

High sound pressure levels (>120dB) cause damage or death of the hair cells of the inner ear, hence causing hearing loss. Vocalization differences are present between hens and roosters. Crowing in roosters is reported to produce sound pressure levels of 100dB measured at a distance of 1m. In this study we measured the sound pressure levels that exist at the entrance of the outer ear canal. We hypothesize that roosters may benefit from a passive protective mechanism while hens do not require such a mechanism. Audio recordings at the level of the entrance of the outer ear canal of crowing roosters, made in this study, indeed show that a protective mechanism is needed as sound pressure levels can reach amplitudes of 142.3dB. Audio recordings made at varying distances from the crowing rooster show that at a distance of 0.5m sound pressure levels already drop to 102dB. Micro-CT scans of a rooster and chicken head show that in roosters the auditory canal closes when the beak is opened. In hens the diameter of the auditory canal only narrows but does not close completely. A morphological difference between the sexes in shape of a bursa-like slit which occurs in the outer ear canal causes the outer ear canal to close in roosters but not in hens. Copyright © 2017 Elsevier GmbH. All rights reserved.

Use of quantitative ultrasonography in differentiating osteomalacia from osteoporosis: preliminary study.

PubMed

Luisetto, G; Camozzi, V; De Terlizzi, F

2000-04-01

The aim of this work was to use ultrasonographic technology to differentiate osteoporosis from osteomalacia on the basis of different patterns of the graphic trace. Three patients with osteomalacia and three with osteoporosis, all with the same lumbar spine bone mineral density, were studied. The velocity of the ultrasound beam in bone was measured by a DBM Sonic 1,200/I densitometer at the proximal phalanges of the hands in all the patients. The ultrasound beam velocity was measured when the first peak of the waveform reached a predetermined minimum amplitude value (amplitude-dependent speed of sound) as well as at the lowest point prior to the first and second peaks, before they reached the predetermined minimum amplitude value (first and second minimum speeds of sound). The graphic traces were further analyzed by Fourier analysis, and both the main frequency (f0) and the width of the peak centered in the f0 (full width at half maximum) were measured. The first and second minimum speeds of sound were significantly lower in the patients with osteomalacia than in the osteoporosis group. The first minimum speed of sound was 2,169 +/- 73 m/s in osteoporosis and 1,983 +/- 61 m/s in osteomalacia (P < 0.0001); the second minimum peak speed of sound was 1,895 +/-59 m/s in osteoporosis and 1,748 +/- 38 m/s in osteomalacia (P < 0.0001). The f0 was similar in the two groups (osteoporosis, 0.85 +/- 0.14 MHz; osteomalacia, 0.9 +/- 0.22 MHz; P = 0.72), and the full width at half maximum was significantly higher in the osteomalacia patients (0.52 +/- 0.14 MHz) than in the osteoporosis patients (0.37 +/- 0.15 MHz) (P = 0.022). This study confirms that ultrasonography is a promising, noninvasive method that could be used to differentiate osteoporosis from osteomalacia, but further studies should be carried out before this method can be introduced into clinical practice.

49 CFR 227.103 - Noise monitoring program.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., significant variations in sound level, or a significant component of impulse noise make area monitoring... results. (c) Noise measurements. (1) All continuous, intermittent, and impulse sound levels from 80...

49 CFR 227.103 - Noise monitoring program.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., significant variations in sound level, or a significant component of impulse noise make area monitoring... results. (c) Noise measurements. (1) All continuous, intermittent, and impulse sound levels from 80...

49 CFR 227.103 - Noise monitoring program.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., significant variations in sound level, or a significant component of impulse noise make area monitoring... results. (c) Noise measurements. (1) All continuous, intermittent, and impulse sound levels from 80...

Atmospheric profiles from active space-based radio measurements

NASA Technical Reports Server (NTRS)

Hardy, Kenneth R.; Hinson, David P.; Tyler, G. L.; Kursinski, E. R.

1992-01-01

The paper describes determinations of atmospheric profiles from space-based radio measurements and the retrieval methodology used, with special attention given to the measurement procedure and the characteristics of the soundings. It is speculated that reliable profiles of the terrestrial atmosphere can be obtained by the occultation technique from the surface to a height of about 60 km. With the full complement of 21 the Global Positioning System (GPS) satellites and one GPS receiver in sun synchronous polar orbit, a maximum of 42 soundings could be obtained for each complete orbit or about 670 per day, providing almost uniform global coverage.

Underwater sound from vessel traffic reduces the effective communication range in Atlantic cod and haddock.

PubMed

Stanley, Jenni A; Van Parijs, Sofie M; Hatch, Leila T

2017-11-07

Stellwagen Bank National Marine Sanctuary is located in Massachusetts Bay off the densely populated northeast coast of the United States; subsequently, the marine inhabitants of the area are exposed to elevated levels of anthropogenic underwater sound, particularly due to commercial shipping. The current study investigated the alteration of estimated effective communication spaces at three spawning locations for populations of the commercially and ecologically important fishes, Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus). Both the ambient sound pressure levels and the estimated effective vocalization radii, estimated through spherical spreading models, fluctuated dramatically during the three-month recording periods. Increases in sound pressure level appeared to be largely driven by large vessel activity, and accordingly exhibited a significant positive correlation with the number of Automatic Identification System tracked vessels at the two of the three sites. The near constant high levels of low frequency sound and consequential reduction in the communication space observed at these recording sites during times of high vocalization activity raises significant concerns that communication between conspecifics may be compromised during critical biological periods. This study takes the first steps in evaluating these animals' communication spaces and alteration of these spaces due to anthropogenic underwater sound.

Cell type-specific suppression of mechanosensitive genes by audible sound stimulation.

PubMed

Kumeta, Masahiro; Takahashi, Daiji; Takeyasu, Kunio; Yoshimura, Shige H

2018-01-01

Audible sound is a ubiquitous environmental factor in nature that transmits oscillatory compressional pressure through the substances. To investigate the property of the sound as a mechanical stimulus for cells, an experimental system was set up using 94.0 dB sound which transmits approximately 10 mPa pressure to the cultured cells. Based on research on mechanotransduction and ultrasound effects on cells, gene responses to the audible sound stimulation were analyzed by varying several sound parameters: frequency, wave form, composition, and exposure time. Real-time quantitative PCR analyses revealed a distinct suppressive effect for several mechanosensitive and ultrasound-sensitive genes that were triggered by sounds. The effect was clearly observed in a wave form- and pressure level-specific manner, rather than the frequency, and persisted for several hours. At least two mechanisms are likely to be involved in this sound response: transcriptional control and RNA degradation. ST2 stromal cells and C2C12 myoblasts exhibited a robust response, whereas NIH3T3 cells were partially and NB2a neuroblastoma cells were completely insensitive, suggesting a cell type-specific response to sound. These findings reveal a cell-level systematic response to audible sound and uncover novel relationships between life and sound.

Cell type-specific suppression of mechanosensitive genes by audible sound stimulation

PubMed Central

Takahashi, Daiji; Takeyasu, Kunio; Yoshimura, Shige H.

2018-01-01

Audible sound is a ubiquitous environmental factor in nature that transmits oscillatory compressional pressure through the substances. To investigate the property of the sound as a mechanical stimulus for cells, an experimental system was set up using 94.0 dB sound which transmits approximately 10 mPa pressure to the cultured cells. Based on research on mechanotransduction and ultrasound effects on cells, gene responses to the audible sound stimulation were analyzed by varying several sound parameters: frequency, wave form, composition, and exposure time. Real-time quantitative PCR analyses revealed a distinct suppressive effect for several mechanosensitive and ultrasound-sensitive genes that were triggered by sounds. The effect was clearly observed in a wave form- and pressure level-specific manner, rather than the frequency, and persisted for several hours. At least two mechanisms are likely to be involved in this sound response: transcriptional control and RNA degradation. ST2 stromal cells and C2C12 myoblasts exhibited a robust response, whereas NIH3T3 cells were partially and NB2a neuroblastoma cells were completely insensitive, suggesting a cell type-specific response to sound. These findings reveal a cell-level systematic response to audible sound and uncover novel relationships between life and sound. PMID:29385174

Statistical inference of seabed sound-speed structure in the Gulf of Oman Basin.

PubMed

Sagers, Jason D; Knobles, David P

2014-06-01

Addressed is the statistical inference of the sound-speed depth profile of a thick soft seabed from broadband sound propagation data recorded in the Gulf of Oman Basin in 1977. The acoustic data are in the form of time series signals recorded on a sparse vertical line array and generated by explosive sources deployed along a 280 km track. The acoustic data offer a unique opportunity to study a deep-water bottom-limited thickly sedimented environment because of the large number of time series measurements, very low seabed attenuation, and auxiliary measurements. A maximum entropy method is employed to obtain a conditional posterior probability distribution (PPD) for the sound-speed ratio and the near-surface sound-speed gradient. The multiple data samples allow for a determination of the average error constraint value required to uniquely specify the PPD for each data sample. Two complicating features of the statistical inference study are addressed: (1) the need to develop an error function that can both utilize the measured multipath arrival structure and mitigate the effects of data errors and (2) the effect of small bathymetric slopes on the structure of the bottom interacting arrivals.

Application of the Fourier pseudospectral time-domain method in orthogonal curvilinear coordinates for near-rigid moderately curved surfaces.

PubMed

Hornikx, Maarten; Dragna, Didier

2015-07-01

The Fourier pseudospectral time-domain method is an efficient wave-based method to model sound propagation in inhomogeneous media. One of the limitations of the method for atmospheric sound propagation purposes is its restriction to a Cartesian grid, confining it to staircase-like geometries. A transform from the physical coordinate system to the curvilinear coordinate system has been applied to solve more arbitrary geometries. For applicability of this method near the boundaries, the acoustic velocity variables are solved for their curvilinear components. The performance of the curvilinear Fourier pseudospectral method is investigated in free field and for outdoor sound propagation over an impedance strip for various types of shapes. Accuracy is shown to be related to the maximum grid stretching ratio and deformation of the boundary shape and computational efficiency is reduced relative to the smallest grid cell in the physical domain. The applicability of the curvilinear Fourier pseudospectral time-domain method is demonstrated by investigating the effect of sound propagation over a hill in a nocturnal boundary layer. With the proposed method, accurate and efficient results for sound propagation over smoothly varying ground surfaces with high impedances can be obtained.

Sound localization in common vampire bats: Acuity and use of the binaural time cue by a small mammal

PubMed Central

Heffner, Rickye S.; Koay, Gimseong; Heffner, Henry E.

2015-01-01

Passive sound-localization acuity and the ability to use binaural time and intensity cues were determined for the common vampire bat (Desmodus rotundus). The bats were tested using a conditioned suppression/avoidance procedure in which they drank defibrinated blood from a spout in the presence of sounds from their right, but stopped drinking (i.e., broke contact with the spout) whenever a sound came from their left, thereby avoiding a mild shock. The mean minimum audible angle for three bats for a 100-ms noise burst was 13.1°—within the range of thresholds for other bats and near the mean for mammals. Common vampire bats readily localized pure tones of 20 kHz and higher, indicating they could use interaural intensity-differences. They could also localize pure tones of 5 kHz and lower, thereby demonstrating the use of interaural time-differences, despite their very small maximum interaural distance of 60 μs. A comparison of the use of locus cues among mammals suggests several implications for the evolution of sound localization and its underlying anatomical and physiological mechanisms. PMID:25618037

Meteorological effects on long-range outdoor sound propagation

NASA Technical Reports Server (NTRS)

Klug, Helmut

1990-01-01

Measurements of sound propagation over distances up to 1000 m were carried out with an impulse sound source offering reproducible, short time signals. Temperature and wind speed at several heights were monitored simultaneously; the meteorological data are used to determine the sound speed gradients according to the Monin-Obukhov similarity theory. The sound speed profile is compared to a corresponding prediction, gained through the measured travel time difference between direct and ground reflected pulse (which depends on the sound speed gradient). Positive sound speed gradients cause bending of the sound rays towards the ground yielding enhanced sound pressure levels. The measured meteorological effects on sound propagation are discussed and illustrated by ray tracing methods.

Linear array transducer for high-power airborne ultrasound using flextensional structure

NASA Astrophysics Data System (ADS)

Yamamoto, Jun; Mizuno, Yosuke; Tabaru, Marie; Nakamura, Kentaro

2015-07-01

To change the direction of ultrasonic irradiation without moving a transducer, a high-power airborne ultrasonic transducer for a one-dimensional phased array system was designed and tested. A flextensional element transducer with higher-mode bending vibration was fabricated to obtain a high vibration amplitude over a wide aperture, where a phase-compensating stepped structure was employed. The width of the main lobe at half maximum and the sidelobe level were measured to be 14.3 deg and 0.78, respectively. The maximal sound pressure of 132 dB (0 dB re. 0.02 mPa) was obtained under the applied voltage of 4.0 V. The beam steering characteristics of a phased array using eight elements were compared with the simple theory.

Automatic loudness control in short-form content for broadcasting.

PubMed

Pires, Leandro da S; Vieira, Maurílio N; Yehia, Hani C

2017-03-01

During the early years of the International Telecommunication Union (ITU) loudness calculation standard for sound broadcasting [ITU-R (2006), Rec. BS Series, 1770], the need for additional loudness descriptors to evaluate short-form content, such as commercials and live inserts, was identified. This work proposes a loudness control scheme to prevent loudness jumps, which can bother audiences. It employs short-form content audio detection and dynamic range processing methods for the maximum loudness level criteria. Detection is achieved by combining principal component analysis for dimensionality reduction and support vector machines for binary classification. Subsequent processing is based on short-term loudness integrators and Hilbert transformers. The performance was assessed using quality classification metrics and demonstrated through a loudness control example.

Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface

PubMed Central

Ryżak, Magdalena; Bieganowski, Andrzej; Korbiel, Tomasz

2016-01-01

The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing–most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon’s characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops. PMID:27388276

Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface.

PubMed

Ryżak, Magdalena; Bieganowski, Andrzej; Korbiel, Tomasz

2016-01-01

The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing-most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon's characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

[Expression of NR2A in rat auditory cortex after sound insulation and auditory plasticity].

PubMed

Xia, Yin; Long, Haishan; Han, Demin; Gong, Shusheng; Lei, Li; Shi, Jinfeng; Fan, Erzhong; Li, Ying; Zhao, Qing

2009-06-01

To study the changes of N-methyl-D-aspartate (NMDA) receptor subunit 2A (NR2A) expression at local synapses in auditory cortices after early postnatal sound insulation and tone exposure. We prepared highly purified synaptosomes from primary auditory cortex by Optiprep flotation gradient centrifugations, and compared the differences of NR2A expression in sound insulation PND14, PND28, PND42 and Tone exposure after sound insulation for 7 days by Western blotting. The results showed that the NR2A protein expression of PND14 and PND28 decreased significantly (P<0.05). Tone exposure after sound insulation for 7 days, mSIe NR2A protein level increased significantly (P<0.05). It showed bidirectional regulation of NR2A protein. No significant effects of sound insulation and lone exposure were found on the relative expression level of NR2A of PND42 (P>0.05). The results indicate that sound insulation and experience can modify the protein expression level of NR2A during the critical period of rat postnatal development. These findings provide important data for the study on the mechanisms of the developmental plasticity of sensory functions.

Measurement and characterisation of radiated underwater sound from a 3.6 MW monopile wind turbine.

PubMed

Pangerc, Tanja; Theobald, Peter D; Wang, Lian S; Robinson, Stephen P; Lepper, Paul A

2016-10-01

This paper describes underwater sound pressure measurements obtained in close proximity (∼50 m) to two individual wind turbines, over a 21-day period, capturing the full range of turbine operating conditions. The sound radiated into the water was characterised by a number of tonal components, which are thought to primarily originate from the gearbox for the bandwidth measured. The main signal associated with the turbine operation had a mean-square sound pressure spectral density level which peaked at 126 dB re 1 μPa 2  Hz -1 at 162 Hz. Other tonal components were also present, notably at frequencies between about 20 and 330 Hz, albeit at lower amplitudes. The measured sound characteristics, both in terms of frequency and amplitude, were shown to vary with wind speed. The sound pressure level increased with wind speed up to an average value of 128 dB re 1 μPa at a wind speed of about 10 ms -1 , and then showed a general decrease. Overall, differences in the mean-square sound pressure spectral density level of over 20 dB were observed across the operational envelope of the turbine.

Designing sound and visual components for enhancement of urban soundscapes.

PubMed

Hong, Joo Young; Jeon, Jin Yong

2013-09-01

The aim of this study is to investigate the effect of audio-visual components on environmental quality to improve soundscape. Natural sounds with road traffic noise and visual components in urban streets were evaluated through laboratory experiments. Waterfall and stream water sounds, as well as bird sounds, were selected to enhance the soundscape. Sixteen photomontages of a streetscape were constructed in combination with two types of water features and three types of vegetation which were chosen as positive visual components. The experiments consisted of audio-only, visual-only, and audio-visual conditions. The preferences and environmental qualities of the stimuli were evaluated by a numerical scale and 12 pairs of adjectives, respectively. The results showed that bird sounds were the most preferred among the natural sounds, while the sound of falling water was found to degrade the soundscape quality when the road traffic noise level was high. The visual effects of vegetation on aesthetic preference were significant, but those of water features relatively small. It was revealed that the perceptual dimensions of the environment were different from the noise levels. Particularly, the acoustic comfort factor related to soundscape quality considerably influenced preference for the overall environment at a higher level of road traffic noise.

Interobserver Agreement on First-Stage Conversation Analytic Transcription

ERIC Educational Resources Information Center

Roberts, Felicia; Robinson, Jeffrey D.

2004-01-01

This investigation assesses interobserver agreement on conversation analytic (CA) transcription. Four professional CA transcribers spent a maximum of 3 hours transcribing 2.5 minutes of a previously unknown, naturally occurring, mundane telephone call. Researchers unitized transcripts into words, sounds, silences, inbreaths, outbreaths, and laugh…

Recovery of burner acoustic source structure from far-field sound spectra

NASA Technical Reports Server (NTRS)

Mahan, J. R.; Jones, J. D.

1984-01-01

A method is presented that permits the thermal-acoustic efficiency spectrum in a long turbulent burner to be recovered from the corresponding far-field sound spectrum. An acoustic source/propagation model is used based on the perturbation solution of the equations describing the unsteady one-dimensional flow of an inviscid ideal gas with a distributed heat source. The technique is applied to a long cylindrical hydrogen-flame burner operating over power levels of 4.5-22.3 kW. The results show that the thermal-acoustic efficiency at a given frequency, defined as the fraction of the total burner power converted to acoustic energy at that frequency, is rather insensitive to burner power, having a maximum value on the order of 10 to the -4th at 150 Hz and rolling off steeply with increasing frequency. Evidence is presented that acoustic agitation of the flame at low frequencies enhances the mixing of the unburned fuel and air with the hot products of combustion. The paper establishes the potential of the technique as a useful tool for characterizing the acoustic source structure in any burner, such as a gas turbine combustor, for which a reasonable acoustic propagation model can be postulated.

Vibration characteristics of bone conducted sound in vitro.

PubMed

Stenfelt, S; Håkansson, B; Tjellström, A

2000-01-01

A dry skull added with damping material was used to investigate the vibratory pattern of bone conducted sound. Three orthogonal vibration responses of the cochleae were measured, by means of miniature accelerometers, in the frequency range 0.1-10 kHz. The exciter was attached to the temporal, parietal, and frontal bones, one at the time. In the transmission response to the ipsilateral cochlea, a profound low frequency antiresonance (attenuation) was found, verified psycho-acoustically, and shown to yield a distinct lateralization effect. It was also shown that, for the ipsilateral side, the direction of excitation coincides with that of maximum response. At the contralateral cochlea, no such dominating response direction was found for frequencies above the first skull resonance. An overall higher response level was achieved, for the total energy transmission in general and specifically for the direction of excitation, at the ipsilateral cochlea when the transducer was attached to the excitation point closest to the cochlea. The transranial attenuation was found to be frequency dependent, with values from -5 to 10 dB for the energy transmission and -30 to 40 dB for measurements in a single direction, with a tendency toward higher attenuation at the higher frequencies.

Beaked whales echolocate on prey.

PubMed Central

Johnson, Mark; Madsen, Peter T; Zimmer, Walter M X; de Soto, Natacha Aguilar; Tyack, Peter L

2004-01-01

Beaked whales (Cetacea: Ziphiidea) of the genera Ziphius and Mesoplodon are so difficult to study that they are mostly known from strandings. How these elusive toothed whales use and react to sound is of concern because they mass strand during naval sonar exercises. A new non-invasive acoustic ording tag was attached to four beaked whales(two Mesoplodon densirostris and two Ziphius cavirostris) and recorded high-frequency clicks during deep dives. The tagged whales only clicked at depths below 200 m, down to a maximum depth of 1267 m. Both species produced a large number of short, directional, ultrasonic clicks with significant energy below 20 kHz. The tags recorded echoes from prey items; to our knowledge, a first for any animal echolocating in the wild. As far as we are aware, these echoes provide the first direct evidence on how free-ranging toothed whales use echolocation in foraging. The strength of these echoes suggests that the source level of Mesoplodon clicks is in the range of 200-220 dB re 1 microPa at 1 m.This paper presents conclusive data on the normal vocalizations of these beaked whale species, which may enable acoustic monitoring to mitigate exposure to sounds intense enough to harm them. PMID:15801582

Mapping the sound field of an erupting submarine volcano using an acoustic glider.

PubMed

Matsumoto, Haru; Haxel, Joseph H; Dziak, Robert P; Bohnenstiehl, Delwayne R; Embley, Robert W

2011-03-01

An underwater glider with an acoustic data logger flew toward a recently discovered erupting submarine volcano in the northern Lau basin. With the volcano providing a wide-band sound source, recordings from the two-day survey produced a two-dimensional sound level map spanning 1 km (depth) × 40 km(distance). The observed sound field shows depth- and range-dependence, with the first-order spatial pattern being consistent with the predictions of a range-dependent propagation model. The results allow constraining the acoustic source level of the volcanic activity and suggest that the glider provides an effective platform for monitoring natural and anthropogenic ocean sounds. © 2011 Acoustical Society of America

Electric field soundings through thunderstorms

NASA Technical Reports Server (NTRS)

Marshall, Thomas C.; Rust, W. D.

1991-01-01

Twelve balloon soundings of the electric field in thunderstorms are reported. The maximum magnitude of E in the storms averaged 96 +/-28 kV/m, with the largest being 146 kV/m. The maximum was usually observed between vertically adjacent regions of opposite charge. Using a 1D approximation to Gauss' law, four to ten charge regions in the storms are inferred. The magnitude of the density in the charge regions varied between 0.2 and 13 nC/cu m. The vertical extent of the charge regions ranged from 130 to 2100 m. None of the present 12 storms had charge distributions that fit the long-accepted model of Simpson et al. (1937, 1941) of a lower positive charge, a main negative charge, and an upper positive charge. In addition to regions similar to the Simpson model, the present storms had screening layers at the upper and lower cloud boundaries and extra charge regions, usually in the lower part of the cloud.

Designing Trend-Monitoring Sounds for Helicopters: Methodological Issues and an Application

ERIC Educational Resources Information Center

Edworthy, Judy; Hellier, Elizabeth; Aldrich, Kirsteen; Loxley, Sarah

2004-01-01

This article explores methodological issues in sonification and sound design arising from the design of helicopter monitoring sounds. Six monitoring sounds (each with 5 levels) were tested for similarity and meaning with 3 different techniques: hierarchical cluster analysis, linkage analysis, and multidimensional scaling. In Experiment 1,…