Origin of acoustic emission produced during single point machining

NASA Astrophysics Data System (ADS)

Heiple, C. R.; Carpenter, S. H.; Armentrout, D. L.

1991-05-01

Acoustic emission was monitored during single point, continuous machining of 4340 steel and Ti-6Al-4V as a function of heat treatment. Acoustic emission produced during tensile and compressive deformation of these alloys has been previously characterized as a function of heat treatment. Heat treatments which increase the strength of 4340 steel increase the amount of acoustic emission produced during deformation, while heat treatments which increase the strength of Ti-6Al-4V decrease the amount of acoustic emission produced during deformation. If chip deformation were the primary source of acoustic emission during single point machining, then opposite trends in the level of acoustic emission produced during machining as a function of material strength would be expected for these two alloys. Trends in rms acoustic emission level with increasing strength were similar for both alloys, demonstrating that chip deformation is not a major source of acoustic emission in single point machining. Acoustic emission has also been monitored as a function of machining parameters on 6061-T6 aluminum, 304 stainless steel, 17-4PH stainless steel, lead, and teflon. The data suggest that sliding friction between the nose and/or flank of the tool and the newly machined surface is the primary source of acoustic emission. Changes in acoustic emission with tool wear were strongly material dependent.

Real-time, in situ monitoring of nanoporation using electric field-induced acoustic signal

NASA Astrophysics Data System (ADS)

Zarafshani, Ali; Faiz, Rowzat; Samant, Pratik; Zheng, Bin; Xiang, Liangzhong

2018-02-01

The use of nanoporation in reversible or irreversible electroporation, e.g. cancer ablation, is rapidly growing. This technique uses an ultra-short and intense electric pulse to increase the membrane permeability, allowing non-permeant drugs and genes access to the cytosol via nanopores in the plasma membrane. It is vital to create a real-time in situ monitoring technique to characterize this process and answer the need created by the successful electroporation procedure of cancer treatment. All suggested monitoring techniques for electroporation currently are for pre-and post-stimulation exposure with no real-time monitoring during electric field exposure. This study was aimed at developing an innovative technology for real-time in situ monitoring of electroporation based on the typical cell exposure-induced acoustic emissions. The acoustic signals are the result of the electric field, which itself can be used in realtime to characterize the process of electroporation. We varied electric field distribution by varying the electric pulse from 1μ - 100ns and varying the voltage intensity from 0 - 1.2ܸ݇ to energize two electrodes in a bi-polar set-up. An ultrasound transducer was used for collecting acoustic signals around the subject under test. We determined the relative location of the acoustic signals by varying the position of the electrodes relative to the transducer and varying the electric field distribution between the electrodes to capture a variety of acoustic signals. Therefore, the electric field that is utilized in the nanoporation technique also produces a series of corresponding acoustic signals. This offers a novel imaging technique for the real-time in situ monitoring of electroporation that may directly improve treatment efficiency.

Call transmission efficiency in native and invasive anurans: competing hypotheses of divergence in acoustic signals.

PubMed

Llusia, Diego; Gómez, Miguel; Penna, Mario; Márquez, Rafael

2013-01-01

Invasive species are a leading cause of the current biodiversity decline, and hence examining the major traits favouring invasion is a key and long-standing goal of invasion biology. Despite the prominent role of the advertisement calls in sexual selection and reproduction, very little attention has been paid to the features of acoustic communication of invasive species in nonindigenous habitats and their potential impacts on native species. Here we compare for the first time the transmission efficiency of the advertisement calls of native and invasive species, searching for competitive advantages for acoustic communication and reproduction of introduced taxa, and providing insights into competing hypotheses in evolutionary divergence of acoustic signals: acoustic adaptation vs. morphological constraints. Using sound propagation experiments, we measured the attenuation rates of pure tones (0.2-5 kHz) and playback calls (Lithobates catesbeianus and Pelophylax perezi) across four distances (1, 2, 4, and 8 m) and over two substrates (water and soil) in seven Iberian localities. All factors considered (signal type, distance, substrate, and locality) affected transmission efficiency of acoustic signals, which was maximized with lower frequency sounds, shorter distances, and over water surface. Despite being broadcast in nonindigenous habitats, the advertisement calls of invasive L. catesbeianus were propagated more efficiently than those of the native species, in both aquatic and terrestrial substrates, and in most of the study sites. This implies absence of optimal relationship between native environments and propagation of acoustic signals in anurans, in contrast to what predicted by the acoustic adaptation hypothesis, and it might render these vertebrates particularly vulnerable to intrusion of invasive species producing low frequency signals, such as L. catesbeianus. Our findings suggest that mechanisms optimizing sound transmission in native habitat can play a less

Call Transmission Efficiency in Native and Invasive Anurans: Competing Hypotheses of Divergence in Acoustic Signals

PubMed Central

Llusia, Diego; Gómez, Miguel; Penna, Mario; Márquez, Rafael

2013-01-01

Invasive species are a leading cause of the current biodiversity decline, and hence examining the major traits favouring invasion is a key and long-standing goal of invasion biology. Despite the prominent role of the advertisement calls in sexual selection and reproduction, very little attention has been paid to the features of acoustic communication of invasive species in nonindigenous habitats and their potential impacts on native species. Here we compare for the first time the transmission efficiency of the advertisement calls of native and invasive species, searching for competitive advantages for acoustic communication and reproduction of introduced taxa, and providing insights into competing hypotheses in evolutionary divergence of acoustic signals: acoustic adaptation vs. morphological constraints. Using sound propagation experiments, we measured the attenuation rates of pure tones (0.2–5 kHz) and playback calls (Lithobates catesbeianus and Pelophylax perezi) across four distances (1, 2, 4, and 8 m) and over two substrates (water and soil) in seven Iberian localities. All factors considered (signal type, distance, substrate, and locality) affected transmission efficiency of acoustic signals, which was maximized with lower frequency sounds, shorter distances, and over water surface. Despite being broadcast in nonindigenous habitats, the advertisement calls of invasive L. catesbeianus were propagated more efficiently than those of the native species, in both aquatic and terrestrial substrates, and in most of the study sites. This implies absence of optimal relationship between native environments and propagation of acoustic signals in anurans, in contrast to what predicted by the acoustic adaptation hypothesis, and it might render these vertebrates particularly vulnerable to intrusion of invasive species producing low frequency signals, such as L. catesbeianus. Our findings suggest that mechanisms optimizing sound transmission in native habitat can play a

The Relationship Between Acoustic Signal Typing and Perceptual Evaluation of Tracheoesophageal Voice Quality for Sustained Vowels.

PubMed

Clapham, Renee P; van As-Brooks, Corina J; van Son, Rob J J H; Hilgers, Frans J M; van den Brekel, Michiel W M

2015-07-01

To investigate the relationship between acoustic signal typing and perceptual evaluation of sustained vowels produced by tracheoesophageal (TE) speakers and the use of signal typing in the clinical setting. Two evaluators independently categorized 1.75-second segments of narrow-band spectrograms according to acoustic signal typing and independently evaluated the recording of the same segments on a visual analog scale according to overall perceptual acoustic voice quality. The relationship between acoustic signal typing and overall voice quality (as a continuous scale and as a four-point ordinal scale) was investigated and the proportion of inter-rater agreement as well as the reliability between the two measures is reported. The agreement between signal type (I-IV) and ordinal voice quality (four-point scale) was low but significant, and there was a significant linear relationship between the variables. Signal type correctly predicted less than half of the voice quality data. There was a significant main effect of signal type on continuous voice quality scores with significant differences in median quality scores between signal types I-IV, I-III, and I-II. Signal typing can be used as an adjunct to perceptual and acoustic evaluation of the same stimuli for TE speech as part of a multidimensional evaluation protocol. Signal typing in its current form provides limited predictive information on voice quality, and there is significant overlap between signal types II and III and perceptual categories. Future work should consider whether the current four signal types could be refined. Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Infrasonic and seismic signals from earthquakes and explosions observed with Plostina seismo-acoustic array

NASA Astrophysics Data System (ADS)

Ghica, D.; Ionescu, C.

2012-04-01

Plostina seismo-acoustic array has been recently deployed by the National Institute for Earth Physics in the central part of Romania, near the Vrancea epicentral area. The array has a 2.5 km aperture and consists of 7 seismic sites (PLOR) and 7 collocated infrasound instruments (IPLOR). The array is being used to assess the importance of collocated seismic and acoustic sensors for the purposes of (1) seismic monitoring of the local and regional events, and (2) acoustic measurement, consisting of detection of the infrasound events (explosions, mine and quarry blasts, earthquakes, aircraft etc.). This paper focuses on characterization of infrasonic and seismic signals from the earthquakes and explosions (accidental and mining type). Two Vrancea earthquakes with magnitude above 5.0 were selected to this study: one occurred on 1st of May 2011 (MD = 5.3, h = 146 km), and the other one, on 4th October 2011 (MD = 5.2, h = 142 km). The infrasonic signals from the earthquakes have the appearance of the vertical component of seismic signals. Because the mechanism of the infrasonic wave formation is the coupling of seismic waves with the atmosphere, trace velocity values for such signals are compatible with the characteristics of the various seismic phases observed with PLOR array. The study evaluates and characterizes, as well, infrasound and seismic data recorded from the explosion caused by the military accident produced at Evangelos Florakis Naval Base, in Cyprus, on 11th July 2011. Additionally, seismo-acoustic signals presumed to be related to strong mine and quarry blasts were investigated. Ground truth of mine observations provides validation of this interpretation. The combined seismo-acoustic analysis uses two types of detectors for signal identification: one is the automatic detector DFX-PMCC, applied for infrasound detection and characterization, while the other one, which is used for seismic data, is based on array processing techniques (beamforming and frequency

Beeping and piping: characterization of two mechano-acoustic signals used by honey bees in swarming

NASA Astrophysics Data System (ADS)

Schlegel, Thomas; Visscher, P. Kirk; Seeley, Thomas D.

2012-12-01

Of the many signals used by honey bees during the process of swarming, two of them—the stop signal and the worker piping signal—are not easily distinguished for both are mechano-acoustic signals produced by scout bees who press their bodies against other bees while vibrating their wing muscles. To clarify the acoustic differences between these two signals, we recorded both signals from the same swarm and at the same time, and compared them in terms of signal duration, fundamental frequency, and frequency modulation. Stop signals and worker piping signals differ in all three variables: duration, 174 ± 64 vs. 602 ± 377 ms; fundamental frequency, 407 vs. 451 Hz; and frequency modulation, absent vs. present. While it remains unclear which differences the bees use to distinguish the two signals, it is clear that they do so for the signals have opposite effects. Stop signals cause inhibition of actively dancing scout bees whereas piping signals cause excitation of quietly resting non-scout bees.

Acoustic properties of naturally produced clear speech at normal speaking rates

NASA Astrophysics Data System (ADS)

Krause, Jean C.; Braida, Louis D.

2004-01-01

Sentences spoken ``clearly'' are significantly more intelligible than those spoken ``conversationally'' for hearing-impaired listeners in a variety of backgrounds [Picheny et al., J. Speech Hear. Res. 28, 96-103 (1985); Uchanski et al., ibid. 39, 494-509 (1996); Payton et al., J. Acoust. Soc. Am. 95, 1581-1592 (1994)]. While producing clear speech, however, talkers often reduce their speaking rate significantly [Picheny et al., J. Speech Hear. Res. 29, 434-446 (1986); Uchanski et al., ibid. 39, 494-509 (1996)]. Yet speaking slowly is not solely responsible for the intelligibility benefit of clear speech (over conversational speech), since a recent study [Krause and Braida, J. Acoust. Soc. Am. 112, 2165-2172 (2002)] showed that talkers can produce clear speech at normal rates with training. This finding suggests that clear speech has inherent acoustic properties, independent of rate, that contribute to improved intelligibility. Identifying these acoustic properties could lead to improved signal processing schemes for hearing aids. To gain insight into these acoustical properties, conversational and clear speech produced at normal speaking rates were analyzed at three levels of detail (global, phonological, and phonetic). Although results suggest that talkers may have employed different strategies to achieve clear speech at normal rates, two global-level properties were identified that appear likely to be linked to the improvements in intelligibility provided by clear/normal speech: increased energy in the 1000-3000-Hz range of long-term spectra and increased modulation depth of low frequency modulations of the intensity envelope. Other phonological and phonetic differences associated with clear/normal speech include changes in (1) frequency of stop burst releases, (2) VOT of word-initial voiceless stop consonants, and (3) short-term vowel spectra.

Acoustic signals in the sand fly Lutzomyia (Nyssomyia) intermedia (Diptera: Psychodidae).

PubMed

Vigoder, Felipe M; Souza, Nataly A; Peixoto, Alexandre A

2011-05-13

Acoustic signals are part of the courtship of many insects and they often act as species-specific signals that are important in the reproductive isolation of closely related species. Here we report the courtship songs of the sand fly Lutzomyia (Nyssomyia) intermedia, one of the main vectors of cutaneous leishmaniasis in Brazil. Recordings were performed using insects from three localities from Eastern Brazil: Posse and Jacarepaguá in Rio de Janeiro State and Corte de Pedra in Bahia State. The three areas have remnants of the Brazilian Atlantic forest, they are endemic for cutaneous leishmaniasis and L. intermedia is the predominant sand fly species. We observed that during courtship L. intermedia males from all populations produced pulse songs consisting of short trains. No significant differences in song parameters were observed between the males of the three localities. L. intermedia males produce acoustic signals as reported for some other sand flies such as the sibling species of the Lutzomyia longipalpis complex. The lack of differences between the males from the three localities is consistent with previous molecular studies of the period gene carried out in the same populations, reinforcing the idea that L. intermedia is not a species complex in the studied areas and that the three populations are likely to have similar vectorial capacities.

Shared developmental and evolutionary origins for neural basis of vocal–acoustic and pectoral–gestural signaling

PubMed Central

Bass, Andrew H.; Chagnaud, Boris P.

2012-01-01

Acoustic signaling behaviors are widespread among bony vertebrates, which include the majority of living fishes and tetrapods. Developmental studies in sound-producing fishes and tetrapods indicate that central pattern generating networks dedicated to vocalization originate from the same caudal hindbrain rhombomere (rh) 8-spinal compartment. Together, the evidence suggests that vocalization and its morphophysiological basis, including mechanisms of vocal–respiratory coupling that are widespread among tetrapods, are ancestral characters for bony vertebrates. Premotor-motor circuitry for pectoral appendages that function in locomotion and acoustic signaling develops in the same rh8-spinal compartment. Hence, vocal and pectoral phenotypes in fishes share both developmental origins and roles in acoustic communication. These findings lead to the proposal that the coupling of more highly derived vocal and pectoral mechanisms among tetrapods, including those adapted for nonvocal acoustic and gestural signaling, originated in fishes. Comparative studies further show that rh8 premotor populations have distinct neurophysiological properties coding for equally distinct behavioral attributes such as call duration. We conclude that neural network innovations in the spatiotemporal patterning of vocal and pectoral mechanisms of social communication, including forelimb gestural signaling, have their evolutionary origins in the caudal hindbrain of fishes. PMID:22723366

Intelligent processing of acoustic emission signals

NASA Astrophysics Data System (ADS)

Sachse, Wolfgang; Grabec, Igor

1992-07-01

Recent developments in applying neural-like signal-processing procedures for analyzing acoustic emission signals are summarized. These procedures employ a set of learning signals to develop a memory that can subsequently be utilized to process other signals to recover information about an unknown source. A majority of the current applications to process ultrasonic waveforms are based on multilayered, feed-forward neural networks, trained with some type of back-error propagation rule.

TH-CD-201-06: Experimental Characterization of Acoustic Signals Generated in Water Following Clinical Photon and Electron Beam Irradiation

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

Hickling, S; El Naqa, I

Purpose: Previous work has demonstrated the detectability of acoustic waves induced following the irradiation of high density metals with radiotherapy linac photon beams. This work demonstrates the ability to experimentally detect such acoustic signals following both photon and electron irradiation in a more radiotherapy relevant material. The relationship between induced acoustic signal properties in water and the deposited dose distribution is explored, and the feasibility of exploiting such signals for radiotherapy dosimetry is demonstrated. Methods: Acoustic waves were experimentally induced in a water tank via the thermoacoustic effect following a single pulse of photon or electron irradiation produced by amore » clinical linac. An immersion ultrasound transducer was used to detect these acoustic waves in water and signals were read out on an oscilloscope. Results: Peaks and troughs in the detected acoustic signals were found to correspond to the location of gradients in the deposited dose distribution following both photon and electron irradiation. Signal amplitude was linearly related to the dose per pulse deposited by photon or electron beams at the depth of detection. Flattening filter free beams induced large acoustic signals, and signal amplitude decreased with depth after the depth of maximum dose. Varying the field size resulted in a temporal shift of the acoustic signal peaks and a change in the detected signal frequency. Conclusion: Acoustic waves can be detected in a water tank following irradiation by linac photon and electron beams with basic electronics, and have characteristics related to the deposited dose distribution. The physical location of dose gradients and the amount of dose deposited can be inferred from the location and magnitude of acoustic signal peaks. Thus, the detection of induced acoustic waves could be applied to photon and electron water tank and in vivo dosimetry. This work was supported in part by CIHR grants MOP-114910 and

Acoustic-Seismic Coupling of Broadband Signals - Analysis of Potential Disturbances during CTBT On-Site Inspection Measurements

NASA Astrophysics Data System (ADS)

Liebsch, Mattes; Altmann, Jürgen

2015-04-01

For the verification of the Comprehensive Nuclear Test Ban Treaty (CTBT) the precise localisation of possible underground nuclear explosion sites is important. During an on-site inspection (OSI) sensitive seismic measurements of aftershocks can be performed, which, however, can be disturbed by other signals. To improve the quality and effectiveness of these measurements it is essential to understand those disturbances so that they can be reduced or prevented. In our work we focus on disturbing signals caused by airborne sources: When the sound of aircraft (as often used by the inspectors themselves) hits the ground, it propagates through pores in the soil. Its energy is transferred to the ground and soil vibrations are created which can mask weak aftershock signals. The understanding of the coupling of acoustic waves to the ground is still incomplete. However, it is necessary to improve the performance of an OSI, e.g. to address potential consequences for the sensor placement, the helicopter trajectories etc. We present our recent advances in this field. We performed several measurements to record sound pressure and soil velocity produced by various sources, e.g. broadband excitation by jet aircraft passing overhead and signals artificially produced by a speaker. For our experimental set-up microphones were placed close to the ground and geophones were buried in different depths in the soil. Several sensors were shielded from the directly incident acoustic signals by a box coated with acoustic damping material. While sound pressure under the box was strongly reduced, the soil velocity measured under the box was just slightly smaller than outside of it. Thus these soil vibrations were mostly created outside the box and travelled through the soil to the sensors. This information is used to estimate characteristic propagation lengths of the acoustically induced signals in the soil. In the seismic data we observed interference patterns which are likely caused by the

Development of an Acoustic Signal Analysis Tool “Auto-F” Based on the Temperament Scale

NASA Astrophysics Data System (ADS)

Modegi, Toshio

The MIDI interface is originally designed for electronic musical instruments but we consider this music-note based coding concept can be extended for general acoustic signal description. We proposed applying the MIDI technology to coding of bio-medical auscultation sound signals such as heart sounds for retrieving medical records and performing telemedicine. Then we have tried to extend our encoding targets including vocal sounds, natural sounds and electronic bio-signals such as ECG, using Generalized Harmonic Analysis method. Currently, we are trying to separate vocal sounds included in popular songs and encode both vocal sounds and background instrumental sounds into separate MIDI channels. And also, we are trying to extract articulation parameters such as MIDI pitch-bend parameters in order to reproduce natural acoustic sounds using a GM-standard MIDI tone generator. In this paper, we present an overall algorithm of our developed acoustic signal analysis tool, based on those research works, which can analyze given time-based signals on the musical temperament scale. The prominent feature of this tool is producing high-precision MIDI codes, which reproduce the similar signals as the given source signal using a GM-standard MIDI tone generator, and also providing analyzed texts in the XML format.

Acoustic signals in the sand fly Lutzomyia (Nyssomyia) intermedia (Diptera: Psychodidae)

PubMed Central

2011-01-01

Background Acoustic signals are part of the courtship of many insects and they often act as species-specific signals that are important in the reproductive isolation of closely related species. Here we report the courtship songs of the sand fly Lutzomyia (Nyssomyia) intermedia, one of the main vectors of cutaneous leishmaniasis in Brazil. Findings Recordings were performed using insects from three localities from Eastern Brazil: Posse and Jacarepaguá in Rio de Janeiro State and Corte de Pedra in Bahia State. The three areas have remnants of the Brazilian Atlantic forest, they are endemic for cutaneous leishmaniasis and L. intermedia is the predominant sand fly species. We observed that during courtship L. intermedia males from all populations produced pulse songs consisting of short trains. No significant differences in song parameters were observed between the males of the three localities. Conclusions L. intermedia males produce acoustic signals as reported for some other sand flies such as the sibling species of the Lutzomyia longipalpis complex. The lack of differences between the males from the three localities is consistent with previous molecular studies of the period gene carried out in the same populations, reinforcing the idea that L. intermedia is not a species complex in the studied areas and that the three populations are likely to have similar vectorial capacities. PMID:21569534

The beluga whale produces two pulses to form its sonar signal

PubMed Central

Lammers, Marc O.; Castellote, Manuel

2009-01-01

Odontocete cetaceans use biosonar clicks to acoustically probe their aquatic environment with an aptitude unmatched by man-made sonar. A cornerstone of this ability is their use of short, broadband pulses produced in the region of the upper nasal passages. Here we provide empirical evidence that a beluga whale (Delphinapterus leucas) uses two signal generators simultaneously when echolocating. We show that the pulses of the two generators are combined as they are transmitted through the melon to produce a single echolocation click emitted from the front of the animal. Generating two pulses probably offers the beluga the ability to control the energy and frequency distribution of the emitted click and may allow it to acoustically steer its echolocation beam. PMID:19324643

Signal Restoration of Non-stationary Acoustic Signals in the Time Domain

NASA Technical Reports Server (NTRS)

Babkin, Alexander S.

1988-01-01

Signal restoration is a method of transforming a nonstationary signal acquired by a ground based microphone to an equivalent stationary signal. The benefit of the signal restoration is a simplification of the flight test requirements because it could dispense with the need to acquire acoustic data with another aircraft flying in concert with the rotorcraft. The data quality is also generally improved because the contamination of the signal by the propeller and wind noise is not present. The restoration methodology can also be combined with other data acquisition methods, such as a multiple linear microphone array for further improvement of the test results. The methodology and software are presented for performing the signal restoration in the time domain. The method has no restrictions on flight path geometry or flight regimes. Only requirement is that the aircraft spatial position be known relative to the microphone location and synchronized with the acoustic data. The restoration process assumes that the moving source radiates a stationary signal, which is then transformed into a nonstationary signal by various modulation processes. The restoration contains only the modulation due to the source motion.

Signal processing for passive detection and classification of underwater acoustic signals

NASA Astrophysics Data System (ADS)

Chung, Kil Woo

2011-12-01

This dissertation examines signal processing for passive detection, classification and tracking of underwater acoustic signals for improving port security and the security of coastal and offshore operations. First, we consider the problem of passive acoustic detection of a diver in a shallow water environment. A frequency-domain multi-band matched-filter approach to swimmer detection is presented. The idea is to break the frequency contents of the hydrophone signals into multiple narrow frequency bands, followed by time averaged (about half of a second) energy calculation over each band. Then, spectra composed of such energy samples over the chosen frequency bands are correlated to form a decision variable. The frequency bands with highest Signal/Noise ratio are used for detection. The performance of the proposed approach is demonstrated for experimental data collected for a diver in the Hudson River. We also propose a new referenceless frequency-domain multi-band detector which, unlike other reference-based detectors, does not require a diver specific signature. Instead, our detector matches to a general feature of the diver spectrum in the high frequency range: the spectrum is roughly periodic in time and approximately flat when the diver exhales. The performance of the proposed approach is demonstrated by using experimental data collected from the Hudson River. Moreover, we present detection, classification and tracking of small vessel signals. Hydroacoustic sensors can be applied for the detection of noise generated by vessels, and this noise can be used for vessel detection, classification and tracking. This dissertation presents recent improvements aimed at the measurement and separation of ship DEMON (Detection of Envelope Modulation on Noise) acoustic signatures in busy harbor conditions. Ship signature measurements were conducted in the Hudson River and NY Harbor. The DEMON spectra demonstrated much better temporal stability compared with the full ship

Graph-based sensor fusion for classification of transient acoustic signals.

PubMed

Srinivas, Umamahesh; Nasrabadi, Nasser M; Monga, Vishal

2015-03-01

Advances in acoustic sensing have enabled the simultaneous acquisition of multiple measurements of the same physical event via co-located acoustic sensors. We exploit the inherent correlation among such multiple measurements for acoustic signal classification, to identify the launch/impact of munition (i.e., rockets, mortars). Specifically, we propose a probabilistic graphical model framework that can explicitly learn the class conditional correlations between the cepstral features extracted from these different measurements. Additionally, we employ symbolic dynamic filtering-based features, which offer improvements over the traditional cepstral features in terms of robustness to signal distortions. Experiments on real acoustic data sets show that our proposed algorithm outperforms conventional classifiers as well as the recently proposed joint sparsity models for multisensor acoustic classification. Additionally our proposed algorithm is less sensitive to insufficiency in training samples compared to competing approaches.

How the environment shapes animal signals: a test of the acoustic adaptation hypothesis in frogs.

PubMed

Goutte, S; Dubois, A; Howard, S D; Márquez, R; Rowley, J J L; Dehling, J M; Grandcolas, P; Xiong, R C; Legendre, F

2018-01-01

Long-distance acoustic signals are widely used in animal communication systems and, in many cases, are essential for reproduction. The acoustic adaptation hypothesis (AAH) implies that acoustic signals should be selected for further transmission and better content integrity under the acoustic constraints of the habitat in which they are produced. In this study, we test predictions derived from the AAH in frogs. Specifically, we focus on the difference between torrent frogs and frogs calling in less noisy habitats. Torrents produce sounds that can mask frog vocalizations and constitute a major acoustic constraint on call evolution. We combine data collected in the field, material from scientific collections and the literature for a total of 79 primarily Asian species, of the families Ranidae, Rhacophoridae, Dicroglossidae and Microhylidae. Using phylogenetic comparative methods and including morphological and environmental potential confounding factors, we investigate putatively adaptive call features in torrent frogs. We use broad habitat categories as well as fine-scale habitat measurements and test their correlation with six call characteristics. We find mixed support for the AAH. Spectral features of torrent frog calls are different from those of frogs calling in other habitats and are related to ambient noise levels, as predicted by the AAH. However, temporal call features do not seem to be shaped by the frogs' calling habitats. Our results underline both the complexity of call evolution and the need to consider multiple factors when investigating this issue. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

PREDICTIVE MODELING OF ACOUSTIC SIGNALS FROM THERMOACOUSTIC POWER SENSORS (TAPS)

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

Dumm, Christopher M.; Vipperman, Jeffrey S.

2016-06-30

Thermoacoustic Power Sensor (TAPS) technology offers the potential for self-powered, wireless measurement of nuclear reactor core operating conditions. TAPS are based on thermoacoustic engines, which harness thermal energy from fission reactions to generate acoustic waves by virtue of gas motion through a porous stack of thermally nonconductive material. TAPS can be placed in the core, where they generate acoustic waves whose frequency and amplitude are proportional to the local temperature and radiation flux, respectively. TAPS acoustic signals are not measured directly at the TAPS; rather, they propagate wirelessly from an individual TAPS through the reactor, and ultimately to a low-powermore » receiver network on the vessel’s exterior. In order to rely on TAPS as primary instrumentation, reactor-specific models which account for geometric/acoustic complexities in the signal propagation environment must be used to predict the amplitude and frequency of TAPS signals at receiver locations. The reactor state may then be derived by comparing receiver signals to the reference levels established by predictive modeling. In this paper, we develop and experimentally benchmark a methodology for predictive modeling of the signals generated by a TAPS system, with the intent of subsequently extending these efforts to modeling of TAPS in a liquid sodium environmen« less

Phase change events of volatile liquid perfluorocarbon contrast agents produce unique acoustic signatures

PubMed Central

Sheeran, Paul S.; Matsunaga, Terry O.; Dayton, Paul A.

2015-01-01

Phase-change contrast agents (PCCAs) provide a dynamic platform to approach problems in medical ultrasound (US). Upon US-mediated activation, the liquid core vaporizes and expands to produce a gas bubble ideal for US imaging and therapy. In this study, we demonstrate through high-speed video microscopy and US interrogation that PCCAs composed of highly volatile perfluorocarbons (PFCs) exhibit unique acoustic behavior that can be detected and differentiated from standard microbubble contrast agents. Experimental results show that when activated with short pulses PCCAs will over-expand and undergo unforced radial oscillation while settling to a final bubble diameter. The size-dependent oscillation phenomenon generates a unique acoustic signal that can be passively detected in both time and frequency domain using confocal piston transducers with an ‘activate high’ (8 MHz, 2 cycles), ‘listen low’ (1 MHz) scheme. Results show that the magnitude of the acoustic ‘signature’ increases as PFC boiling point decreases. By using a band-limited spectral processing technique, the droplet signals can be isolated from controls and used to build experimental relationships between concentration and vaporization pressure. The techniques shown here may be useful for physical studies as well as development of droplet-specific imaging techniques. PMID:24351961

System And Method For Characterizing Voiced Excitations Of Speech And Acoustic Signals, Removing Acoustic Noise From Speech, And Synthesizi

DOEpatents

Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

2006-04-25

The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

Primary acoustic signal structure during free falling drop collision with a water surface

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

Chashechkin, Yu. D., E-mail: chakin@ipmnet.ru; Prokhorov, V. E., E-mail: prohorov@ipmnet.ru

2016-04-15

Consistent optical and acoustic techniques have been used to study the structure of hydrodynamic disturbances and acoustic signals generated as a free falling drop penetrates water. The relationship between the structures of hydrodynamic and acoustic perturbations arising as a result of a falling drop contacting with the water surface and subsequent immersion into water is traced. The primary acoustic signal is characterized, in addition to stably reproduced features (steep leading edge followed by long decay with local pressure maxima), by irregular high-frequency packets, which are studied for the first time. Reproducible experimental data are used to recognize constant and variablemore » components of the primary acoustic signal.« less

An Investigation of Acoustic Cavitation Produced by Pulsed Ultrasound

DTIC Science & Technology

1987-12-01

S~ PVDF Hydrophone Sensitivity Calibration Curves C. DESCRIPTION OF TEST AND CALIBRATION TECHNIQUE We chose the reciprocity technique for calibration...NAVAL POSTGRADUATE SCHOOLN a n Monterey, Calif ornia ITHESIS AN INVESTIGATION OF ACOUSTIC CAVITATION PRODUCED BY PULSED ULTRASOUND by Robert L. Bruce...INVESTIGATION OF ACOUSTIC CAVITATION PRODUCED B~Y PULSED ULTRASOUND !2 PERSONAL AUTHOR(S) .RR~r. g~rtL_ 1DLJN, Rober- ., Jr. 13a TYPE OF REPORT )3b TIME

Acoustic transducer for nuclear reactor monitoring

DOEpatents

Ahlgren, Frederic F.; Scott, Paul F.

1977-01-01

A transducer to monitor a parameter and produce an acoustic signal from which the monitored parameter can be recovered. The transducer comprises a modified Galton whistle which emits a narrow band acoustic signal having a frequency dependent upon the parameter being monitored, such as the temperature of the cooling media of a nuclear reactor. Multiple locations within a reactor are monitored simultaneously by a remote acoustic receiver by providing a plurality of transducers each designed so that the acoustic signal it emits has a frequency distinct from the frequencies of signals emitted by the other transducers, whereby each signal can be unambiguously related to a particular transducer.

The potential influence of morphology on the evolutionary divergence of an acoustic signal

PubMed Central

Pitchers, W. R.; Klingenberg, C.P.; Tregenza, Tom; Hunt, J.; Dworkin, I.

2014-01-01

The evolution of acoustic behaviour and that of the morphological traits mediating its production are often coupled. Lack of variation in the underlying morphology of signalling traits has the potential to constrain signal evolution. This relationship is particularly likely in field crickets, where males produce acoustic advertisement signals to attract females by stridulating with specialized structures on their forewings. In this study, we characterise the size and geometric shape of the forewings of males from six allopatric populations of the black field cricket (Teleogryllus commodus) known to have divergent advertisement calls. We sample from each of these populations using both wild-caught and common-garden reared cohorts, allowing us to test for multivariate relationships between wing morphology and call structure. We show that the allometry of shape has diverged across populations. However, there was a surprisingly small amount of covariation between wing shape and call structure within populations. Given the importance of male size for sexual selection in crickets, the divergence we observe among populations has the potential to influence the evolution of advertisement calls in this species. PMID:25223712

Prediction of acoustic feature parameters using myoelectric signals.

PubMed

Lee, Ki-Seung

2010-07-01

It is well-known that a clear relationship exists between human voices and myoelectric signals (MESs) from the area of the speaker's mouth. In this study, we utilized this information to implement a speech synthesis scheme in which MES alone was used to predict the parameters characterizing the vocal-tract transfer function of specific speech signals. Several feature parameters derived from MES were investigated to find the optimal feature for maximization of the mutual information between the acoustic and the MES features. After the optimal feature was determined, an estimation rule for the acoustic parameters was proposed, based on a minimum mean square error (MMSE) criterion. In a preliminary study, 60 isolated words were used for both objective and subjective evaluations. The results showed that the average Euclidean distance between the original and predicted acoustic parameters was reduced by about 30% compared with the average Euclidean distance of the original parameters. The intelligibility of the synthesized speech signals using the predicted features was also evaluated. A word-level identification ratio of 65.5% and a syllable-level identification ratio of 73% were obtained through a listening test.

Modeling of acoustic emission signal propagation in waveguides.

PubMed

Zelenyak, Andreea-Manuela; Hamstad, Marvin A; Sause, Markus G R

2015-05-21

Acoustic emission (AE) testing is a widely used nondestructive testing (NDT) method to investigate material failure. When environmental conditions are harmful for the operation of the sensors, waveguides are typically mounted in between the inspected structure and the sensor. Such waveguides can be built from different materials or have different designs in accordance with the experimental needs. All these variations can cause changes in the acoustic emission signals in terms of modal conversion, additional attenuation or shift in frequency content. A finite element method (FEM) was used to model acoustic emission signal propagation in an aluminum plate with an attached waveguide and was validated against experimental data. The geometry of the waveguide is systematically changed by varying the radius and height to investigate the influence on the detected signals. Different waveguide materials were implemented and change of material properties as function of temperature were taken into account. Development of the option of modeling different waveguide options replaces the time consuming and expensive trial and error alternative of experiments. Thus, the aim of this research has important implications for those who use waveguides for AE testing.

Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)

1995-01-01

An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

NASA Technical Reports Server (NTRS)

Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)

1994-01-01

An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

Detection and Classification of Whale Acoustic Signals

NASA Astrophysics Data System (ADS)

Xian, Yin

This dissertation focuses on two vital challenges in relation to whale acoustic signals: detection and classification. In detection, we evaluated the influence of the uncertain ocean environment on the spectrogram-based detector, and derived the likelihood ratio of the proposed Short Time Fourier Transform detector. Experimental results showed that the proposed detector outperforms detectors based on the spectrogram. The proposed detector is more sensitive to environmental changes because it includes phase information. In classification, our focus is on finding a robust and sparse representation of whale vocalizations. Because whale vocalizations can be modeled as polynomial phase signals, we can represent the whale calls by their polynomial phase coefficients. In this dissertation, we used the Weyl transform to capture chirp rate information, and used a two dimensional feature set to represent whale vocalizations globally. Experimental results showed that our Weyl feature set outperforms chirplet coefficients and MFCC (Mel Frequency Cepstral Coefficients) when applied to our collected data. Since whale vocalizations can be represented by polynomial phase coefficients, it is plausible that the signals lie on a manifold parameterized by these coefficients. We also studied the intrinsic structure of high dimensional whale data by exploiting its geometry. Experimental results showed that nonlinear mappings such as Laplacian Eigenmap and ISOMAP outperform linear mappings such as PCA and MDS, suggesting that the whale acoustic data is nonlinear. We also explored deep learning algorithms on whale acoustic data. We built each layer as convolutions with either a PCA filter bank (PCANet) or a DCT filter bank (DCTNet). With the DCT filter bank, each layer has different a time-frequency scale representation, and from this, one can extract different physical information. Experimental results showed that our PCANet and DCTNet achieve high classification rate on the whale

The effect of habitat acoustics on common marmoset vocal signal transmission.

PubMed

Morrill, Ryan J; Thomas, A Wren; Schiel, Nicola; Souto, Antonio; Miller, Cory T

2013-09-01

Noisy acoustic environments present several challenges for the evolution of acoustic communication systems. Among the most significant is the need to limit degradation of spectro-temporal signal structure in order to maintain communicative efficacy. This can be achieved by selecting for several potentially complementary processes. Selection can act on behavioral mechanisms permitting signalers to control the timing and occurrence of signal production to avoid acoustic interference. Likewise, the signal itself may be the target of selection, biasing the evolution of its structure to comprise acoustic features that avoid interference from ambient noise or degrade minimally in the habitat. Here, we address the latter topic for common marmoset (Callithrix jacchus) long-distance contact vocalizations, known as phee calls. Our aim was to test whether this vocalization is specifically adapted for transmission in a species-typical forest habitat, the Atlantic forests of northeastern Brazil. We combined seasonal analyses of ambient habitat acoustics with experiments in which pure tones, clicks, and vocalizations were broadcast and rerecorded at different distances to characterize signal degradation in the habitat. Ambient sound was analyzed from intervals throughout the day and over rainy and dry seasons, showing temporal regularities across varied timescales. Broadcast experiment results indicated that the tone and click stimuli showed the typically inverse relationship between frequency and signaling efficacy. Although marmoset phee calls degraded over distance with marked predictability compared with artificial sounds, they did not otherwise appear to be specially designed for increased transmission efficacy or minimal interference in this habitat. We discuss these data in the context of other similar studies and evidence of potential behavioral mechanisms for avoiding acoustic interference in order to maintain effective vocal communication in common marmosets. © 2013

The Effect of Habitat Acoustics on Common Marmoset Vocal Signal Transmission

PubMed Central

MORRILL, RYAN J.; THOMAS, A. WREN; SCHIEL, NICOLA; SOUTO, ANTONIO; MILLER, CORY T.

2013-01-01

Noisy acoustic environments present several challenges for the evolution of acoustic communication systems. Among the most significant is the need to limit degradation of spectro-temporal signal structure in order to maintain communicative efficacy. This can be achieved by selecting for several potentially complementary processes. Selection can act on behavioral mechanisms permitting signalers to control the timing and occurrence of signal production to avoid acoustic interference. Likewise, the signal itself may be the target of selection, biasing the evolution of its structure to comprise acoustic features that avoid interference from ambient noise or degrade minimally in the habitat. Here, we address the latter topic for common marmoset (Callithrix jacchus) long-distance contact vocalizations, known as phee calls. Our aim was to test whether this vocalization is specifically adapted for transmission in a species-typical forest habitat, the Atlantic forests of northeastern Brazil. We combined seasonal analyses of ambient habitat acoustics with experiments in which pure tones, clicks, and vocalizations were broadcast and rerecorded at different distances to characterize signal degradation in the habitat. Ambient sound was analyzed from intervals throughout the day and over rainy and dry seasons, showing temporal regularities across varied timescales. Broadcast experiment results indicated that the tone and click stimuli showed the typically inverse relationship between frequency and signaling efficacy. Although marmoset phee calls degraded over distance with marked predictability compared with artificial sounds, they did not otherwise appear to be specially designed for increased transmission efficacy or minimal interference in this habitat. We discuss these data in the context of other similar studies and evidence of potential behavioral mechanisms for avoiding acoustic interference in order to maintain effective vocal communication in common marmosets. PMID

System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

DOEpatents

Burnett, Greg C [Livermore, CA; Holzrichter, John F [Berkeley, CA; Ng, Lawrence C [Danville, CA

2006-08-08

The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

DOEpatents

Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

2004-03-23

The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

DOEpatents

Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

2006-02-14

The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

Surface acoustic wave dust deposition monitor

DOEpatents

Fasching, G.E.; Smith, N.S. Jr.

1988-02-12

A system is disclosed for using the attenuation of surface acoustic waves to monitor real time dust deposition rates on surfaces. The system includes a signal generator, a tone-burst generator/amplifier connected to a transmitting transducer for converting electrical signals into acoustic waves. These waves are transmitted through a path defining means adjacent to a layer of dust and then, in turn, transmitted to a receiving transducer for changing the attenuated acoustic wave to electrical signals. The signals representing the attenuated acoustic waves may be amplified and used in a means for analyzing the output signals to produce an output indicative of the dust deposition rates and/or values of dust in the layer. 8 figs.

Intense acoustic bursts as a signal-enhancement mechanism in ultrasound-modulated optical tomography.

PubMed

Kim, Chulhong; Zemp, Roger J; Wang, Lihong V

2006-08-15

Biophotonic imaging with ultrasound-modulated optical tomography (UOT) promises ultrasonically resolved imaging in biological tissues. A key challenge in this imaging technique is a low signal-to-noise ratio (SNR). We show significant UOT signal enhancement by using intense time-gated acoustic bursts. A CCD camera captured the speckle pattern from a laser-illuminated tissue phantom. Differences in speckle contrast were observed when ultrasonic bursts were applied, compared with when no ultrasound was applied. When CCD triggering was synchronized with burst initiation, acoustic-radiation-force-induced displacements were detected. To avoid mechanical contrast in UOT images, the CCD camera acquisition was delayed several milliseconds until transient effects of acoustic radiation force attenuated to a satisfactory level. The SNR of our system was sufficiently high to provide an image pixel per acoustic burst without signal averaging. Because of the substantially improved SNR, the use of intense acoustic bursts is a promising signal enhancement strategy for UOT.

Acoustic effects of the ATOC signal (75 Hz, 195 dB) on dolphins and whales

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

Au, W.W.; Nachtigall, P.E.; Pawloski, J.L.

1997-05-01

The Acoustic Thermometry of Ocean Climate (ATOC) program of Scripps Institution of Oceanography and the Applied Physics Laboratory, University of Washington, will broadcast a low-frequency 75-Hz phase modulated acoustic signal over ocean basins in order to study ocean temperatures on a global scale and examine the effects of global warming. One of the major concerns is the possible effect of the ATOC signal on marine life, especially on dolphins and whales. In order to address this issue, the hearing sensitivity of a false killer whale ({ital Pseudorca crassidens}) and a Risso{close_quote}s dolphin ({ital Grampus griseus}) to the ATOC sound wasmore » measured behaviorally. A staircase procedure with the signal levels being changed in 1-dB steps was used to measure the animals{close_quote} threshold to the actual ATOC coded signal. The results indicate that small odontocetes such as the {ital Pseudorca} and {ital Grampus} swimming directly above the ATOC source will not hear the signal unless they dive to a depth of approximately 400 m. A sound propagation analysis suggests that the sound-pressure level at ranges greater than 0.5 km will be less than 130 dB for depths down to about 500 m. Several species of baleen whales produce sounds much greater than 170{endash}180 dB. With the ATOC source on the axis of the deep sound channel (greater than 800 m), the ATOC signal will probably have minimal physical and physiological effects on cetaceans. {copyright} {ital 1997 Acoustical Society of America.}« less

Coupled Research in Ocean Acoustics and Signal Processing for the Next Generation of Underwater Acoustic Communication Systems

DTIC Science & Technology

2016-08-05

JPAnalytics LLC CC: DCMA Boston DTIC Director, NRL Progress Report #8 Coupled Research in Ocean Acoustics and Signal Processing for the Next...Generation of Underwater Acoustic Communication Systems Principal Investigator’s Name: Dr. James Preisig Period Covered By Report: 1/20/2016 to 4/19/2016...Technical work this period has spanned two areas. The first of these is VHF Acoustics . During this time period, the Principle Investigator worked with Dr

Acoustic/seismic signal propagation and sensor performance modeling

NASA Astrophysics Data System (ADS)

Wilson, D. Keith; Marlin, David H.; Mackay, Sean

2007-04-01

Performance, optimal employment, and interpretation of data from acoustic and seismic sensors depend strongly and in complex ways on the environment in which they operate. Software tools for guiding non-expert users of acoustic and seismic sensors are therefore much needed. However, such tools require that many individual components be constructed and correctly connected together. These components include the source signature and directionality, representation of the atmospheric and terrain environment, calculation of the signal propagation, characterization of the sensor response, and mimicking of the data processing at the sensor. Selection of an appropriate signal propagation model is particularly important, as there are significant trade-offs between output fidelity and computation speed. Attenuation of signal energy, random fading, and (for array systems) variations in wavefront angle-of-arrival should all be considered. Characterization of the complex operational environment is often the weak link in sensor modeling: important issues for acoustic and seismic modeling activities include the temporal/spatial resolution of the atmospheric data, knowledge of the surface and subsurface terrain properties, and representation of ambient background noise and vibrations. Design of software tools that address these challenges is illustrated with two examples: a detailed target-to-sensor calculation application called the Sensor Performance Evaluator for Battlefield Environments (SPEBE) and a GIS-embedded approach called Battlefield Terrain Reasoning and Awareness (BTRA).

Micro acoustic spectrum analyzer

DOEpatents

Schubert, W. Kent; Butler, Michael A.; Adkins, Douglas R.; Anderson, Larry F.

2004-11-23

A micro acoustic spectrum analyzer for determining the frequency components of a fluctuating sound signal comprises a microphone to pick up the fluctuating sound signal and produce an alternating current electrical signal; at least one microfabricated resonator, each resonator having a different resonant frequency, that vibrate in response to the alternating current electrical signal; and at least one detector to detect the vibration of the microfabricated resonators. The micro acoustic spectrum analyzer can further comprise a mixer to mix a reference signal with the alternating current electrical signal from the microphone to shift the frequency spectrum to a frequency range that is a better matched to the resonant frequencies of the microfabricated resonators. The micro acoustic spectrum analyzer can be designed specifically for portability, size, cost, accuracy, speed, power requirements, and use in a harsh environment. The micro acoustic spectrum analyzer is particularly suited for applications where size, accessibility, and power requirements are limited, such as the monitoring of industrial equipment and processes, detection of security intrusions, or evaluation of military threats.

System and method for investigating sub-surface features of a rock formation with acoustic sources generating coded signals

DOEpatents

Vu, Cung Khac; Nihei, Kurt; Johnson, Paul A; Guyer, Robert; Ten Cate, James A; Le Bas, Pierre-Yves; Larmat, Carene S

2014-12-30

A system and a method for investigating rock formations includes generating, by a first acoustic source, a first acoustic signal comprising a first plurality of pulses, each pulse including a first modulated signal at a central frequency; and generating, by a second acoustic source, a second acoustic signal comprising a second plurality of pulses. A receiver arranged within the borehole receives a detected signal including a signal being generated by a non-linear mixing process from the first-and-second acoustic signal in a non-linear mixing zone within the intersection volume. The method also includes-processing the received signal to extract the signal generated by the non-linear mixing process over noise or over signals generated by a linear interaction process, or both.

Circuit for echo and noise suppression of acoustic signals transmitted through a drill string

DOEpatents

Drumheller, D.S.; Scott, D.D.

1993-12-28

An electronic circuit for digitally processing analog electrical signals produced by at least one acoustic transducer is presented. In a preferred embodiment of the present invention, a novel digital time delay circuit is utilized which employs an array of First-in-First-out (FiFo) microchips. Also, a bandpass filter is used at the input to this circuit for isolating drill string noise and eliminating high frequency output. 20 figures.

Bird population density estimated from acoustic signals

USGS Publications Warehouse

Dawson, D.K.; Efford, M.G.

2009-01-01

Many animal species are detected primarily by sound. Although songs, calls and other sounds are often used for population assessment, as in bird point counts and hydrophone surveys of cetaceans, there are few rigorous methods for estimating population density from acoustic data. 2. The problem has several parts - distinguishing individuals, adjusting for individuals that are missed, and adjusting for the area sampled. Spatially explicit capture-recapture (SECR) is a statistical methodology that addresses jointly the second and third parts of the problem. We have extended SECR to use uncalibrated information from acoustic signals on the distance to each source. 3. We applied this extension of SECR to data from an acoustic survey of ovenbird Seiurus aurocapilla density in an eastern US deciduous forest with multiple four-microphone arrays. We modelled average power from spectrograms of ovenbird songs measured within a window of 0??7 s duration and frequencies between 4200 and 5200 Hz. 4. The resulting estimates of the density of singing males (0??19 ha -1 SE 0??03 ha-1) were consistent with estimates of the adult male population density from mist-netting (0??36 ha-1 SE 0??12 ha-1). The fitted model predicts sound attenuation of 0??11 dB m-1 (SE 0??01 dB m-1) in excess of losses from spherical spreading. 5.Synthesis and applications. Our method for estimating animal population density from acoustic signals fills a gap in the census methods available for visually cryptic but vocal taxa, including many species of bird and cetacean. The necessary equipment is simple and readily available; as few as two microphones may provide adequate estimates, given spatial replication. The method requires that individuals detected at the same place are acoustically distinguishable and all individuals vocalize during the recording interval, or that the per capita rate of vocalization is known. We believe these requirements can be met, with suitable field methods, for a significant

Digital Signal Processing in Acoustics--Part 2.

ERIC Educational Resources Information Center

Davies, H.; McNeill, D. J.

1986-01-01

Reviews the potential of a data acquisition system for illustrating the nature and significance of ideas in digital signal processing. Focuses on the fast Fourier transform and the utility of its two-channel format, emphasizing cross-correlation and its two-microphone technique of acoustic intensity measurement. Includes programing format. (ML)

Leak detection in gas pipeline by acoustic and signal processing - A review

NASA Astrophysics Data System (ADS)

Adnan, N. F.; Ghazali, M. F.; Amin, M. M.; Hamat, A. M. A.

2015-12-01

The pipeline system is the most important part in media transport in order to deliver fluid to another station. The weak maintenance and poor safety will contribute to financial losses in term of fluid waste and environmental impacts. There are many classifications of techniques to make it easier to show their specific method and application. This paper's discussion about gas leak detection in pipeline system using acoustic method will be presented in this paper. The wave propagation in the pipeline is a key parameter in acoustic method when the leak occurs and the pressure balance of the pipe will generated by the friction between wall in the pipe. The signal processing is used to decompose the raw signal and show in time- frequency. Findings based on the acoustic method can be used for comparative study in the future. Acoustic signal and HHT is the best method to detect leak in gas pipelines. More experiments and simulation need to be carried out to get the fast result of leaking and estimation of their location.

Impact of the Test Device on the Behavior of the Acoustic Emission Signals: Contribution of the Numerical Modeling to Signal Processing

NASA Astrophysics Data System (ADS)

Issiaka Traore, Oumar; Cristini, Paul; Favretto-Cristini, Nathalie; Pantera, Laurent; Viguier-Pla, Sylvie

2018-01-01

In a context of nuclear safety experiment monitoring with the non destructive testing method of acoustic emission, we study the impact of the test device on the interpretation of the recorded physical signals by using spectral finite element modeling. The numerical results are validated by comparison with real acoustic emission data obtained from previous experiments. The results show that several parameters can have significant impacts on acoustic wave propagation and then on the interpretation of the physical signals. The potential position of the source mechanism, the positions of the receivers and the nature of the coolant fluid have to be taken into account in the definition a pre-processing strategy of the real acoustic emission signals. In order to show the relevance of such an approach, we use the results to propose an optimization of the positions of the acoustic emission sensors in order to reduce the estimation bias of the time-delay and then improve the localization of the source mechanisms.

Amplitude calibration of an acoustic backscattered signal from a bottom-moored ADCP based on long-term measurement series

NASA Astrophysics Data System (ADS)

Piotukh, V. B.; Zatsepin, A. G.; Kuklev, S. B.

2017-05-01

A possible approach to, and preliminary results of, amplitude calibration of acoustic signals backscattered from an ADCP moored at the bottom of the near-shelf zone of the Black Sea is considered. The aim of this work is to obtain vertical profiles of acoustic scattering signal levels, showing the real characteristics of the volume content of suspended sediments in sea water in units of conventional acoustic turbidity for a given signal frequency. In this case, the assumption about the intervals of maximum acoustic transparency and vertical homogeneity of the marine environment in long-term series of ADCP measurements is used. According to this hypothesis, the intervals of the least values of acoustic backscattered signals are detected, an empirical transfer function of the ADCP reception path is constructed, and it is calibrated. Normalized sets of acoustic backscattered signals relative to a signal from a level of conventionally clear water are obtained. New features in the behavior of vertical profiles of an acoustic echo-signal are revealed due to the calibration. The results of this work will be used in subsequent analysis of the vertical and time variations in suspended sediment content in the near-shelf zone of the Black Sea.

Mesoscale variations in acoustic signals induced by atmospheric gravity waves.

PubMed

Chunchuzov, Igor; Kulichkov, Sergey; Perepelkin, Vitaly; Ziemann, Astrid; Arnold, Klaus; Kniffka, Anke

2009-02-01

The results of acoustic tomographic monitoring of the coherent structures in the lower atmosphere and the effects of these structures on acoustic signal parameters are analyzed in the present study. From the measurements of acoustic travel time fluctuations (periods 1 min-1 h) with distant receivers, the temporal fluctuations of the effective sound speed and wind speed are retrieved along different ray paths connecting an acoustic pulse source and several receivers. By using a coherence analysis of the fluctuations near spatially distanced ray turning points, the internal wave-associated fluctuations are filtered and their spatial characteristics (coherences, horizontal phase velocities, and spatial scales) are estimated. The capability of acoustic tomography in estimating wind shear near ground is shown. A possible mechanism describing the temporal modulation of the near-ground wind field by ducted internal waves in the troposphere is proposed.

Investigation of Volcanic Seismo-Acoustic Signals: Applying Subspace Detection to Lava Fountain Activity at Etna Volcano

NASA Astrophysics Data System (ADS)

Sciotto, M.; Rowe, C. A.; Cannata, A.; Arrowsmith, S.; Privitera, E.; Gresta, S.

2011-12-01

The current eruption of Mount Etna, which began in January, 2011, has produced numerous energetic episodes of lava fountaining, which have bee recorded by the INGV seismic and acoustic sensors located on and around the volcano. The source of these events was the pit crater on the east flank of the Southeast crater of Etna. Simultaneously, small levels of activity were noted in the Bocca Nuova as well, prior to its lava fountaining activity. We will present an analysis of seismic and acoustic signals related to the 2011 activity wherein we apply the method of subspace detection to determine whether the source exhibits a temporal evolution within or between fountaining events, or otherwise produces repeating, classifiable events occurring through the continuous explosive degassing. We will examine not only the raw waveforms, but also spectral variations in time as well as time-varying statistical functions such as signal skewness and kurtosis. These results will be compared to straightforward cross-correlation analysis. In addition to classification performance, the subspace method has promise to outperform standard STA/LTA methods for real-time event detection in cases where similar events can be expected.

Impacts of underwater turbulence on acoustical and optical signals and their linkage.

PubMed

Hou, Weilin; Jarosz, Ewa; Woods, Sarah; Goode, Wesley; Weidemann, Alan

2013-02-25

Acoustical and optical signal transmission underwater is of vital interest for both civilian and military applications. The range and signal to noise during the transmission, as a function of system and water optical properties, in terms of absorption and scattering, determines the effectiveness of deployed electro-optical (EO) technology. The impacts from turbulence have been demonstrated to affect system performance comparable to those from particles by recent studies. This paper examines the impacts from underwater turbulence on both acoustic scattering and EO imaging degradation, and establishes a framework that can be used to correlate these. It is hypothesized here that underwater turbulence would influence the acoustic scattering cross section and the optical turbulence intensity coefficient in a similar manner. Data from a recent field campaign, Skaneateles Optical Turbulence Exercise (SOTEX, July, 2010) is used to examine the above relationship. Results presented here show strong correlation between the acoustic scattering cross-sections and the intensity coefficient related to the modulation transfer function of an EO imaging system. This significant finding will pave ways to utilize long range acoustical returns to predict EO system performance.

Levitation of objects using acoustic energy

NASA Technical Reports Server (NTRS)

Whymark, R. R.

1975-01-01

Activated sound source establishes standing-wave pattern in gap between source and acoustic reflector. Solid or liquid material introduced in region will move to one of the low pressure areas produced at antinodes and remain suspended as long as acoustic signal is present.

[Research on Time-frequency Characteristics of Magneto-acoustic Signal of Different Thickness Medium Based on Wave Summing Method].

PubMed

Zhang, Shunqi; Yin, Tao; Ma, Ren; Liu, Zhipeng

2015-08-01

Functional imaging method of biological electrical characteristics based on magneto-acoustic effect gives valuable information of tissue in early tumor diagnosis, therein time and frequency characteristics analysis of magneto-acoustic signal is important in image reconstruction. This paper proposes wave summing method based on Green function solution for acoustic source of magneto-acoustic effect. Simulations and analysis under quasi 1D transmission condition are carried out to time and frequency characteristics of magneto-acoustic signal of models with different thickness. Simulation results of magneto-acoustic signal were verified through experiments. Results of the simulation with different thickness showed that time-frequency characteristics of magneto-acoustic signal reflected thickness of sample. Thin sample, which is less than one wavelength of pulse, and thick sample, which is larger than one wavelength, showed different summed waveform and frequency characteristics, due to difference of summing thickness. Experimental results verified theoretical analysis and simulation results. This research has laid a foundation for acoustic source and conductivity reconstruction to the medium with different thickness in magneto-acoustic imaging.

Acoustic Location of Lightning Using Interferometric Techniques

NASA Astrophysics Data System (ADS)

Erives, H.; Arechiga, R. O.; Stock, M.; Lapierre, J. L.; Edens, H. E.; Stringer, A.; Rison, W.; Thomas, R. J.

2013-12-01

Acoustic arrays have been used to accurately locate thunder sources in lightning flashes. The acoustic arrays located around the Magdalena mountains of central New Mexico produce locations which compare quite well with source locations provided by the New Mexico Tech Lightning Mapping Array. These arrays utilize 3 outer microphones surrounding a 4th microphone located at the center, The location is computed by band-passing the signal to remove noise, and then computing the cross correlating the outer 3 microphones with respect the center reference microphone. While this method works very well, it works best on signals with high signal to noise ratios; weaker signals are not as well located. Therefore, methods are being explored to improve the location accuracy and detection efficiency of the acoustic location systems. The signal received by acoustic arrays is strikingly similar to th signal received by radio frequency interferometers. Both acoustic location systems and radio frequency interferometers make coherent measurements of a signal arriving at a number of closely spaced antennas. And both acoustic and interferometric systems then correlate these signals between pairs of receivers to determine the direction to the source of the received signal. The primary difference between the two systems is the velocity of propagation of the emission, which is much slower for sound. Therefore, the same frequency based techniques that have been used quite successfully with radio interferometers should be applicable to acoustic based measurements as well. The results presented here are comparisons between the location results obtained with current cross correlation method and techniques developed for radio frequency interferometers applied to acoustic signals. The data were obtained during the summer 2013 storm season using multiple arrays sensitive to both infrasonic frequency and audio frequency acoustic emissions from lightning. Preliminary results show that

Usage Autocorrelation Function in the Capacity of Indicator Shape of the Signal in Acoustic Emission Testing of Intricate Castings

NASA Astrophysics Data System (ADS)

Popkov, Artem

2016-01-01

The article contains information about acoustic emission signals analysing using autocorrelation function. Operation factors were analysed, such as shape of signal, the origins time and carrier frequency. The purpose of work is estimating the validity of correlations methods analysing signals. Acoustic emission signal consist of different types of waves, which propagate on different trajectories in object of control. Acoustic emission signal is amplitude-, phase- and frequency-modeling signal. It was described by carrier frequency at a given point of time. Period of signal make up 12.5 microseconds and carrier frequency make up 80 kHz for analysing signal. Usage autocorrelation function like indicator the origin time of acoustic emission signal raises validity localization of emitters.

Acoustic effects of the ATOC signal (75 Hz, 195 dB) on dolphins and whales.

PubMed

Au, W W; Nachtigall, P E; Pawloski, J L

1997-05-01

The Acoustic Thermometry of Ocean Climate (ATOC) program of Scripps Institution of Oceanography and the Applied Physics Laboratory, University of Washington, will broadcast a low-frequency 75-Hz phase modulated acoustic signal over ocean basins in order to study ocean temperatures on a global scale and examine the effects of global warming. One of the major concerns is the possible effect of the ATOC signal on marine life, especially on dolphins and whales. In order to address this issue, the hearing sensitivity of a false killer whale (Pseudorca crassidens) and a Risso's dolphin (Grampus griseus) to the ATOC sound was measured behaviorally. A staircase procedure with the signal levels being changed in 1-dB steps was used to measure the animals' threshold to the actual ATOC coded signal. The results indicate that small odontocetes such as the Pseudorca and Grampus swimming directly above the ATOC source will not hear the signal unless they dive to a depth of approximately 400 m. A sound propagation analysis suggests that the sound-pressure level at ranges greater than 0.5 km will be less than 130 dB for depths down to about 500 m. Several species of baleen whales produce sounds much greater than 170-180 dB. With the ATOC source on the axis of the deep sound channel (greater than 800 m), the ATOC signal will probably have minimal physical and physiological effects on cetaceans.

The broadband social acoustic signaling behavior of spinner and spotted dolphins

NASA Astrophysics Data System (ADS)

Lammers, Marc O.; Au, Whitlow W. L.; Herzing, Denise L.

2003-09-01

Efforts to study the social acoustic signaling behavior of delphinids have traditionally been restricted to audio-range (<20 kHz) analyses. To explore the occurrence of communication signals at ultrasonic frequencies, broadband recordings of whistles and burst pulses were obtained from two commonly studied species of delphinids, the Hawaiian spinner dolphin (Stenella longirostris) and the Atlantic spotted dolphin (Stenella frontalis). Signals were quantitatively analyzed to establish their full bandwidth, to identify distinguishing characteristics between each species, and to determine how often they occur beyond the range of human hearing. Fundamental whistle contours were found to extend beyond 20 kHz only rarely among spotted dolphins, but with some regularity in spinner dolphins. Harmonics were present in the majority of whistles and varied considerably in their number, occurrence, and amplitude. Many whistles had harmonics that extended past 50 kHz and some reached as high as 100 kHz. The relative amplitude of harmonics and the high hearing sensitivity of dolphins to equivalent frequencies suggest that harmonics are biologically relevant spectral features. The burst pulses of both species were found to be predominantly ultrasonic, often with little or no energy below 20 kHz. The findings presented reveal that the social signals produced by spinner and spotted dolphins span the full range of their hearing sensitivity, are spectrally quite varied, and in the case of burst pulses are probably produced more frequently than reported by audio-range analyses.

The broadband social acoustic signaling behavior of spinner and spotted dolphins.

PubMed

Lammers, Marc O; Au, Whitlow W L; Herzing, Denise L

2003-09-01

Efforts to study the social acoustic signaling behavior of delphinids have traditionally been restricted to audio-range (<20 kHz) analyses. To explore the occurrence of communication signals at ultrasonic frequencies, broadband recordings of whistles and burst pulses were obtained from two commonly studied species of delphinids, the Hawaiian spinner dolphin (Stenella longirostris) and the Atlantic spotted dolphin (Stenella frontalis). Signals were quantitatively analyzed to establish their full bandwidth, to identify distinguishing characteristics between each species, and to determine how often they occur beyond the range of human hearing. Fundamental whistle contours were found to extend beyond 20 kHz only rarely among spotted dolphins, but with some regularity in spinner dolphins. Harmonics were present in the majority of whistles and varied considerably in their number, occurrence, and amplitude. Many whistles had harmonics that extended past 50 kHz and some reached as high as 100 kHz. The relative amplitude of harmonics and the high hearing sensitivity of dolphins to equivalent frequencies suggest that harmonics are biologically relevant spectral features. The burst pulses of both species were found to be predominantly ultrasonic, often with little or no energy below 20 kHz. The findings presented reveal that the social signals produced by spinner and spotted dolphins span the full range of their hearing sensitivity, are spectrally quite varied, and in the case of burst pulses are probably produced more frequently than reported by audio-range analyses.

Seismic and acoustic signal identification algorithms

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

LADD,MARK D.; ALAM,M. KATHLEEN; SLEEFE,GERARD E.

2000-04-03

This paper will describe an algorithm for detecting and classifying seismic and acoustic signals for unattended ground sensors. The algorithm must be computationally efficient and continuously process a data stream in order to establish whether or not a desired signal has changed state (turned-on or off). The paper will focus on describing a Fourier based technique that compares the running power spectral density estimate of the data to a predetermined signature in order to determine if the desired signal has changed state. How to establish the signature and the detection thresholds will be discussed as well as the theoretical statisticsmore » of the algorithm for the Gaussian noise case with results from simulated data. Actual seismic data results will also be discussed along with techniques used to reduce false alarms due to the inherent nonstationary noise environments found with actual data.« less

Dependencies and Ill-designed Parameters Within High-speed Videoendoscopy and Acoustic Signal Analysis.

PubMed

Schlegel, Patrick; Stingl, Michael; Kunduk, Melda; Kniesburges, Stefan; Bohr, Christopher; Döllinger, Michael

2018-05-31

The phonatory process is often judged during sustained phonation by analyzing the acoustic voice signal and the vocal fold vibrations. Many formulas and parameters have been suggested for qualifying the characteristics of the acoustic signal and the vocal fold vibrations during sustained phonation. These parameters are directly computed from the acoustic signal and the endoscopic glottal area waveform (GAW). The GAW is calculated from laryngeal high-speed videoendoscopy (HSV) recordings and describes the increase and decrease of the glottal area during the phonation process, that is, the opening and closing of the two oscillating vocal folds over time. However, some of the parameters have strong mathematical dependencies with one another and some are ill-defined. The purpose of this study is to identify mathematical dependencies between parameters with the aim of reducing their numbers and suggesting which parameters may best describe the properties of the GAW and the acoustical signal. In this preliminary investigation, 20 frequently used parameters are examined: 10 GAW only and 10 both GAW and acoustic parameters. In total 13 parameters can be neglected because of mathematical dependencies. In addition, nine of these parameters show problematic features that range from unexpected behavior to ill definition. Reducing the number of parameters appears to be necessary to standardize vocal fold function analysis. This may lead to better comparability of research results from different studies. Copyright © 2018 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Substrate vibrations during acoustic signalling in the cicada Okanagana rimosa

PubMed Central

Stölting, Heiko; Moore, Thomas E.; Lakes-Harlan, Reinhard

2002-01-01

Males of the North American cicada Okanagana rimosa (Homoptera: Cicadidae, Tibicininae) emit loud airborne acoustic signals for intraspecific communication. Specialised vibratory signals could not be detected; however, the airborne signal induced substrate vibrations. Both auditory and vibratory spectra peak in the range from 7–10 kHz. Thus, the vibrations show similar frequency components to the sound spectrum within biologically relevant distances. These vibratory signals could be important as signals involved in mate localization and perhaps even as the context for the evolution of the ear in a group of parasitoid flies. PMID:15455036

The S-Matrix and Acoustic Signal Structure in Simple and Compound Waveguides.

DTIC Science & Technology

1982-12-01

RD-A125 583 THE S-MATRIX AND ACOUSTIC SIGNAL STRUCTURE IN SIMPLE- L/1 AND COMPOUND WAVEGUIDES(U) UTAH UNIV SALT LAKE CITY DEPT OF MATHEMATICS C H...WILCOX DEC 82 TSR-45 UNCLASSIFIED N6@8i4-76-C-8276 F/G 12/1 NL IEINEIIIIIIEIhllhlllllllIflllllflflflflflEN L-- U5-12 III,2,0 III.J --IL.,5 MICROCOP ...RESLUIO TETCHRNATIONA BUREA OF 20NADS16 THE S-MATRIX AND ACOUSTIC SIGNAL STRUCTURE IN SIMPLE AND COMPOUND WAVEGUIDES C. H. Wilcox Technical Simmary Report

Extraction of fault component from abnormal sound in diesel engines using acoustic signals

NASA Astrophysics Data System (ADS)

Dayong, Ning; Changle, Sun; Yongjun, Gong; Zengmeng, Zhang; Jiaoyi, Hou

2016-06-01

In this paper a method for extracting fault components from abnormal acoustic signals and automatically diagnosing diesel engine faults is presented. The method named dislocation superimposed method (DSM) is based on the improved random decrement technique (IRDT), differential function (DF) and correlation analysis (CA). The aim of DSM is to linearly superpose multiple segments of abnormal acoustic signals because of the waveform similarity of faulty components. The method uses sample points at the beginning of time when abnormal sound appears as the starting position for each segment. In this study, the abnormal sound belonged to shocking faulty type; thus, the starting position searching method based on gradient variance was adopted. The coefficient of similar degree between two same sized signals is presented. By comparing with a similar degree, the extracted fault component could be judged automatically. The results show that this method is capable of accurately extracting the fault component from abnormal acoustic signals induced by faulty shocking type and the extracted component can be used to identify the fault type.

System for producing chroma signals

NASA Technical Reports Server (NTRS)

Vorhaben, K. H.; Lipoma, P. C. (Inventor)

1977-01-01

A method for obtaining electronic chroma signals with a single scanning-type image device is described. A color multiplexed light signal is produced using an arrangement of dichroic filter stripes. In the particular system described, a two layer filter is used to color modulate external light which is then detected by an image pickup tube. The resulting time division multiplexed electronic signal from the pickup tube is converted by a decoder into a green color signal, and a single red-blue multiplexed signal, which is demultiplexed to produce red and blue color signals. The three primary color signals can be encoded as standard NTSC color signals.

Acoustic signal emission monitoring as a novel method to predict steam pops during radiofrequency ablation: preliminary observations.

PubMed

Chik, William W B; Kosobrodov, Roman; Bhaskaran, Abhishek; Barry, Michael Anthony Tony; Nguyen, Doan Trang; Pouliopoulos, Jim; Byth, Karen; Sivagangabalan, Gopal; Thomas, Stuart P; Ross, David L; McEwan, Alistair; Kovoor, Pramesh; Thiagalingam, Aravinda

2015-04-01

Steam pop is an explosive rupture of cardiac tissue caused by tissue overheating above 100 °C, resulting in steam formation, predisposing to serious complications associated with radiofrequency (RF) ablations. However, there are currently no reliable techniques to predict the occurrence of steam pops. We propose the utility of acoustic signals emitted during RF ablation as a novel method to predict steam pop formation and potentially prevent serious complications. Radiofrequency generator parameters (power, impedance, and temperature) were temporally recorded during ablations performed in an in vitro bovine myocardial model. The acoustic system consisted of HTI-96-min hydrophone, microphone preamplifier, and sound card connected to a laptop computer. The hydrophone has the frequency range of 2 Hz to 30 kHz and nominal sensitivity in the range -240 to -165 dB. The sound was sampled at 96 kHz with 24-bit resolution. Output signal from the hydrophone was fed into the camera audio input to synchronize the video stream. An automated system was developed for the detection and analysis of acoustic events. Nine steam pops were observed. Three distinct sounds were identified as warning signals, each indicating rapid steam formation and its release from tissue. These sounds had a broad frequency range up to 6 kHz with several spectral peaks around 2-3 kHz. Subjectively, these warning signals were perceived as separate loud clicks, a quick succession of clicks, or continuous squeaking noise. Characteristic acoustic signals were identified preceding 80% of pops occurrence. Six cardiologists were able to identify 65% of acoustic signals accurately preceding the pop. An automated system identified the characteristic warning signals in 85% of cases. The mean time from the first acoustic signal to pop occurrence was 46 ± 20 seconds. The automated system had 72.7% sensitivity and 88.9% specificity for predicting pops. Easily identifiable characteristic acoustic emissions

Signal processing methodologies for an acoustic fetal heart rate monitor

NASA Technical Reports Server (NTRS)

Pretlow, Robert A., III; Stoughton, John W.

1992-01-01

Research and development is presented of real time signal processing methodologies for the detection of fetal heart tones within a noise-contaminated signal from a passive acoustic sensor. A linear predictor algorithm is utilized for detection of the heart tone event and additional processing derives heart rate. The linear predictor is adaptively 'trained' in a least mean square error sense on generic fetal heart tones recorded from patients. A real time monitor system is described which outputs to a strip chart recorder for plotting the time history of the fetal heart rate. The system is validated in the context of the fetal nonstress test. Comparisons are made with ultrasonic nonstress tests on a series of patients. Comparative data provides favorable indications of the feasibility of the acoustic monitor for clinical use.

Customization of the acoustic field produced by a piezoelectric array through interelement delays

PubMed Central

Chitnis, Parag V.; Barbone, Paul E.; Cleveland, Robin O.

2008-01-01

A method for producing a prescribed acoustic pressure field from a piezoelectric array was investigated. The array consisted of 170 elements placed on the inner surface of a 15 cm radius spherical cap. Each element was independently driven by using individual pulsers each capable of generating 1.2 kV. Acoustic field customization was achieved by independently controlling the time when each element was excited. The set of time delays necessary to produce a particular acoustic field was determined by using an optimization scheme. The acoustic field at the focal plane was simulated by using the angular spectrum method, and the optimization searched for the time delays that minimized the least squared difference between the magnitudes of the simulated and desired pressure fields. The acoustic field was shaped in two different ways: the −6 dB focal width was increased to different desired widths and the ring-shaped pressure distributions of various prescribed diameters were produced. For both cases, the set of delays resulting from the respective optimization schemes were confirmed to yield the desired pressure distributions by using simulations and measurements. The simulations, however, predicted peak positive pressures roughly half those obtained from the measurements, which was attributed to the exclusion of nonlinearity in the simulations. PMID:18537369

Analyzing the acoustic beat with mobile devices

NASA Astrophysics Data System (ADS)

Kuhn, Jochen; Vogt, Patrik; Hirth, Michael

2014-04-01

In this column, we have previously presented various examples of how physical relationships can be examined by analyzing acoustic signals using smartphones or tablet PCs. In this example, we will be exploring the acoustic phenomenon of small beats, which is produced by the overlapping of two tones with a low difference in frequency Δf. The resulting auditory sensation is a tone with a volume that varies periodically. Acoustic beats can be perceived repeatedly in day-to-day life and have some interesting applications. For example, string instruments are still tuned with the help of an acoustic beat, even with modern technology. If a reference tone (e.g., 440 Hz) and, for example, a slightly out-of-tune violin string produce a tone simultaneously, a beat can be perceived. The more similar the frequencies, the longer the duration of the beat. In the extreme case, when the frequencies are identical, a beat no longer arises. The string is therefore correctly tuned. Using the Oscilloscope app,4 it is possible to capture and save acoustic signals of this kind and determine the beat frequency fS of the signal, which represents the difference in frequency Δf of the two overlapping tones (for Android smartphones, the app OsciPrime Oscilloscope can be used).

Data quality enhancement and knowledge discovery from relevant signals in acoustic emission

NASA Astrophysics Data System (ADS)

Mejia, Felipe; Shyu, Mei-Ling; Nanni, Antonio

2015-10-01

The increasing popularity of structural health monitoring has brought with it a growing need for automated data management and data analysis tools. Of great importance are filters that can systematically detect unwanted signals in acoustic emission datasets. This study presents a semi-supervised data mining scheme that detects data belonging to unfamiliar distributions. This type of outlier detection scheme is useful detecting the presence of new acoustic emission sources, given a training dataset of unwanted signals. In addition to classifying new observations (herein referred to as "outliers") within a dataset, the scheme generates a decision tree that classifies sub-clusters within the outlier context set. The obtained tree can be interpreted as a series of characterization rules for newly-observed data, and they can potentially describe the basic structure of different modes within the outlier distribution. The data mining scheme is first validated on a synthetic dataset, and an attempt is made to confirm the algorithms' ability to discriminate outlier acoustic emission sources from a controlled pencil-lead-break experiment. Finally, the scheme is applied to data from two fatigue crack-growth steel specimens, where it is shown that extracted rules can adequately describe crack-growth related acoustic emission sources while filtering out background "noise." Results show promising performance in filter generation, thereby allowing analysts to extract, characterize, and focus only on meaningful signals.

Temperature and Pressure Dependence of Signal Amplitudes for Electrostriction Laser-Induced Thermal Acoustics

NASA Technical Reports Server (NTRS)

Herring, Gregory C.

2015-01-01

The relative signal strength of electrostriction-only (no thermal grating) laser-induced thermal acoustics (LITA) in gas-phase air is reported as a function of temperature T and pressure P. Measurements were made in the free stream of a variable Mach number supersonic wind tunnel, where T and P are varied simultaneously as Mach number is varied. Using optical heterodyning, the measured signal amplitude (related to the optical reflectivity of the acoustic grating) was averaged for each of 11 flow conditions and compared to the expected theoretical dependence of a pure-electrostriction LITA process, where the signal is proportional to the square root of [P*P /( T*T*T)].

Portable Multi Hydrophone Array for Field and Laboratory Measurements of Odontocete Acoustic Signals

DTIC Science & Technology

2014-09-30

false killer whale . Our analysis will also be conducted with current passive acoustic monitoring detectors and classifiers in order to assess if the...obtain horizontal and vertical beam patterns of acoustic signals of a false killer whale and a bottlenose dolphin. The data is currently being

Seismo-acoustic signals associated with degassing explosions recorded at Shishaldin Volcano, Alaska, 2003-2004

USGS Publications Warehouse

Petersen, T.

2007-01-01

In summer 2003, a Chaparral Model 2 microphone was deployed at Shishaldin Volcano, Aleutian Islands, Alaska. The pressure sensor was co-located with a short-period seismometer on the volcano’s north flank at a distance of 6.62 km from the active summit vent. The seismo-acoustic data exhibit a correlation between impulsive acoustic signals (1–2 Pa) and long-period (LP, 1–2 Hz) earthquakes. Since it last erupted in 1999, Shishaldin has been characterized by sustained seismicity consisting of many hundreds to two thousand LP events per day. The activity is accompanied by up to ∼200 m high discrete gas puffs exiting the small summit vent, but no significant eruptive activity has been confirmed. The acoustic waveforms possess similarity throughout the data set (July 2003–November 2004) indicating a repetitive source mechanism. The simplicity of the acoustic waveforms, the impulsive onsets with relatively short (∼10–20 s) gradually decaying codas and the waveform similarities suggest that the acoustic pulses are generated at the fluid–air interface within an open-vent system. SO2 measurements have revealed a low SO2 flux, suggesting a hydrothermal system with magmatic gases leaking through. This hypothesis is supported by the steady-state nature of Shishaldin’s volcanic system since 1999. Time delays between the seismic LP and infrasound onsets were acquired from a representative day of seismo-acoustic data. A simple model was used to estimate source depths. The short seismo-acoustic delay times have revealed that the seismic and acoustic sources are co-located at a depth of 240±200 m below the crater rim. This shallow depth is confirmed by resonance of the upper portion of the open conduit, which produces standing waves with f=0.3 Hz in the acoustic waveform codas. The infrasound data has allowed us to relate Shishaldin’s LP earthquakes to degassing explosions, created by gas volume ruptures from a fluid–air interface.

Removing Background Noise with Phased Array Signal Processing

NASA Technical Reports Server (NTRS)

Podboy, Gary; Stephens, David

2015-01-01

Preliminary results are presented from a test conducted to determine how well microphone phased array processing software could pull an acoustic signal out of background noise. The array consisted of 24 microphones in an aerodynamic fairing designed to be mounted in-flow. The processing was conducted using Functional Beam forming software developed by Optinav combined with cross spectral matrix subtraction. The test was conducted in the free-jet of the Nozzle Acoustic Test Rig at NASA GRC. The background noise was produced by the interaction of the free-jet flow with the solid surfaces in the flow. The acoustic signals were produced by acoustic drivers. The results show that the phased array processing was able to pull the acoustic signal out of the background noise provided the signal was no more than 20 dB below the background noise level measured using a conventional single microphone equipped with an aerodynamic forebody.

Method for simultaneously making a plurality of acoustic signal sensor elements

NASA Technical Reports Server (NTRS)

Bryant, Timothy D. (Inventor); Wynkoop, Mark W. (Inventor); Holloway, Nancy M. H. (Inventor); Zuckerwar, Allan J. (Inventor)

2005-01-01

A fetal heart monitoring system preferably comprising a backing plate having a generally concave front surface and a generally convex back surface, and at least one sensor element attached to the concave front surface for acquiring acoustic fetal heart signals produced by a fetus within a body. The sensor element has a shape that conforms to the generally concave back surface of the backing plate. In one embodiment, the at least one sensor element comprises an inner sensor, and a plurality of outer sensors surrounding the inner sensor. The fetal heart monitoring system can further comprise a web belt, and a web belt guide movably attached to the web belt. The web belt guide being is to the convex back surface of the backing plate.

Method for Simultaneously Making a Plurality of Acoustic Signal Sensor Elements

NASA Technical Reports Server (NTRS)

Bryant, Timothy D.; Wynkoop, Mark W.; Holloway, Nancy M. H.; Zuckerwar, Allan J.

2005-01-01

A fetal heart monitoring system preferably comprising a backing plate having a generally concave front surface and a generally convex back surface, and at least one sensor element attached to the concave front surface for acquiring acoustic fetal heart signals produced by a fetus within a body. The sensor element has a shape that conforms to the generally concave back surface of the backing plate. In one embodiment, the at least one sensor element comprises an inner sensor, and a plurality of outer sensors surrounding the inner sensor. The fetal heart monitoring system can further comprise a web belt, and a web belt guide movably attached to the web belt. The web belt guide being is to the convex back surface of the backing plate.

Low-frequency signals produced by Northeast Atlantic killer whales (Orcinus orca).

PubMed

Samarra, Filipa I P; Deecke, Volker B; Miller, Patrick J O

2016-03-01

Killer whale acoustic behavior has been extensively investigated; however, most studies have focused on pulsed calls and whistles. This study reports the production of low-frequency signals by killer whales at frequencies below 300 Hz. Recordings were made in Iceland and Norway when killer whales were observed feeding on herring and no other marine mammal species were nearby. Low-frequency sounds were identified in Iceland and ranged in duration between 0.14 and 2.77 s and in frequency between 50 and 270 Hz, well below the previously reported lower limit for killer whale tonal sounds of 500 Hz. Low-frequency sounds appeared to be produced close in time to tail slaps, which are indicative of feeding attempts, suggesting that these sounds may be related to a feeding context. However, their precise function is unknown, and they could be the by-product of a non-vocal behavior rather than a vocal signal deliberately produced by the whales. Although killer whales in Norway exhibit similar feeding behavior, this sound has not been detected in recordings from Norway to date. This study suggests that, like other delphinids, killer whales produce low-frequency sounds, but further studies will be required to understand whether similar sounds exist in other killer whale populations.

Systems and methods for biometric identification using the acoustic properties of the ear canal

DOEpatents

Bouchard, Ann Marie; Osbourn, Gordon Cecil

1998-01-01

The present invention teaches systems and methods for verifying or recognizing a person's identity based on measurements of the acoustic response of the individual's ear canal. The system comprises an acoustic emission device, which emits an acoustic source signal s(t), designated by a computer, into the ear canal of an individual, and an acoustic response detection device, which detects the acoustic response signal f(t). A computer digitizes the response (detected) signal f(t) and stores the data. Computer-implemented algorithms analyze the response signal f(t) to produce ear-canal feature data. The ear-canal feature data obtained during enrollment is stored on the computer, or some other recording medium, to compare the enrollment data with ear-canal feature data produced in a subsequent access attempt, to determine if the individual has previously been enrolled. The system can also be adapted for remote access applications.

Systems and methods for biometric identification using the acoustic properties of the ear canal

DOEpatents

Bouchard, A.M.; Osbourn, G.C.

1998-07-28

The present invention teaches systems and methods for verifying or recognizing a person`s identity based on measurements of the acoustic response of the individual`s ear canal. The system comprises an acoustic emission device, which emits an acoustic source signal s(t), designated by a computer, into the ear canal of an individual, and an acoustic response detection device, which detects the acoustic response signal f(t). A computer digitizes the response (detected) signal f(t) and stores the data. Computer-implemented algorithms analyze the response signal f(t) to produce ear-canal feature data. The ear-canal feature data obtained during enrollment is stored on the computer, or some other recording medium, to compare the enrollment data with ear-canal feature data produced in a subsequent access attempt, to determine if the individual has previously been enrolled. The system can also be adapted for remote access applications. 5 figs.

Lightning Location Using Acoustic Signals

NASA Astrophysics Data System (ADS)

Badillo, E.; Arechiga, R. O.; Thomas, R. J.

2013-05-01

In the summer of 2011 and 2012 a network of acoustic arrays was deployed in the Magdalena mountains of central New Mexico to locate lightning flashes. A Times-Correlation (TC) ray-tracing-based-technique was developed in order to obtain the location of lightning flashes near the network. The TC technique, locates acoustic sources from lightning. It was developed to complement the lightning location of RF sources detected by the Lightning Mapping Array (LMA) developed at Langmuir Laboratory, in New Mexico Tech. The network consisted of four arrays with four microphones each. The microphones on each array were placed in a triangular configuration with one of the microphones in the center of the array. The distance between the central microphone and the rest of them was about 30 m. The distance between centers of the arrays ranged from 500 m to 1500 m. The TC technique uses times of arrival (TOA) of acoustic waves to trace back the location of thunder sources. In order to obtain the times of arrival, the signals were filtered in a frequency band of 2 to 20 hertz and cross-correlated. Once the times of arrival were obtained, the Levenberg-Marquardt algorithm was applied to locate the spatial coordinates (x,y, and z) of thunder sources. Two techniques were used and contrasted to compute the accuracy of the TC method: Nearest-Neighbors (NN), between acoustic and LMA located sources, and standard deviation from the curvature matrix of the system as a measure of dispersion of the results. For the best case scenario, a triggered lightning event, the TC method applied with four microphones, located sources with a median error of 152 m and 142.9 m using nearest-neighbors and standard deviation respectively.; Results of the TC method in the lightning event recorded at 18:47:35 UTC, August 6, 2012. Black dots represent the results computed. Light color dots represent the LMA data for the same event. The results were obtained with the MGTM station (four channels). This figure

Neural Mechanisms for Acoustic Signal Detection under Strong Masking in an Insect

PubMed Central

Römer, Heiner

2015-01-01

Communication is fundamental for our understanding of behavior. In the acoustic modality, natural scenes for communication in humans and animals are often very noisy, decreasing the chances for signal detection and discrimination. We investigated the mechanisms enabling selective hearing under natural noisy conditions for auditory receptors and interneurons of an insect. In the studied katydid Mecopoda elongata species-specific calling songs (chirps) are strongly masked by signals of another species, both communicating in sympatry. The spectral properties of the two signals are similar and differ only in a small frequency band at 2 kHz present in the chirping species. Receptors sharply tuned to 2 kHz are completely unaffected by the masking signal of the other species, whereas receptors tuned to higher audio and ultrasonic frequencies show complete masking. Intracellular recordings of identified interneurons revealed two mechanisms providing response selectivity to the chirp. (1) Response selectivity is when several identified interneurons exhibit remarkably selective responses to the chirps, even at signal-to-noise ratios of −21 dB, since they are sharply tuned to 2 kHz. Their dendritic arborizations indicate selective connectivity with low-frequency receptors tuned to 2 kHz. (2) Novelty detection is when a second group of interneurons is broadly tuned but, because of strong stimulus-specific adaptation to the masker spectrum and “novelty detection” to the 2 kHz band present only in the conspecific signal, these interneurons start to respond selectively to the chirp shortly after the onset of the continuous masker. Both mechanisms provide the sensory basis for hearing at unfavorable signal-to-noise ratios. SIGNIFICANCE STATEMENT Animal and human acoustic communication may suffer from the same “cocktail party problem,” when communication happens in noisy social groups. We address solutions for this problem in a model system of two katydids, where one

Investigation of signal models and methods for evaluating structures of processing telecommunication information exchange systems under acoustic noise conditions

NASA Astrophysics Data System (ADS)

Kropotov, Y. A.; Belov, A. A.; Proskuryakov, A. Y.; Kolpakov, A. A.

2018-05-01

The paper considers models and methods for estimating signals during the transmission of information messages in telecommunication systems of audio exchange. One-dimensional probability distribution functions that can be used to isolate useful signals, and acoustic noise interference are presented. An approach to the estimation of the correlation and spectral functions of the parameters of acoustic signals is proposed, based on the parametric representation of acoustic signals and the components of the noise components. The paper suggests an approach to improving the efficiency of interference cancellation and highlighting the necessary information when processing signals from telecommunications systems. In this case, the suppression of acoustic noise is based on the methods of adaptive filtering and adaptive compensation. The work also describes the models of echo signals and the structure of subscriber devices in operational command telecommunications systems.

A study on locating the sonic source of sinusoidal magneto-acoustic signals using a vector method.

PubMed

Zhang, Shunqi; Zhou, Xiaoqing; Ma, Ren; Yin, Tao; Liu, Zhipeng

2015-01-01

Methods based on the magnetic-acoustic effect are of great significance in studying the electrical imaging properties of biological tissues and currents. The continuous wave method, which is commonly used, can only detect the current amplitude without the sound source position. Although the pulse mode adopted in magneto-acoustic imaging can locate the sonic source, the low measuring accuracy and low SNR has limited its application. In this study, a vector method was used to solve and analyze the magnetic-acoustic signal based on the continuous sine wave mode. This study includes theory modeling of the vector method, simulations to the line model, and experiments with wire samples to analyze magneto-acoustic (MA) signal characteristics. The results showed that the amplitude and phase of the MA signal contained the location information of the sonic source. The amplitude and phase obeyed the vector theory in the complex plane. This study sets a foundation for a new technique to locate sonic sources for biomedical imaging of tissue conductivity. It also aids in studying biological current detecting and reconstruction based on the magneto-acoustic effect.

Remote Acoustic Monitoring of North Atlantic Right Whales (Eubalaena glacialis) Reveals Seasonal and Diel Variations in Acoustic Behavior

PubMed Central

Matthews, Leanna P.; McCordic, Jessica A.; Parks, Susan E.

2014-01-01

Remote acoustic monitoring is a non-invasive tool that can be used to study the distribution, behavior, and habitat use of sound-producing species. The North Atlantic right whale (Eubalaena glacialis) is an endangered baleen whale species that produces a variety of stereotyped acoustic signals. One of these signals, the “gunshot” sound, has only been recorded from adult male North Atlantic right whales and is thought to function for reproduction, either as reproductive advertisement for females or as an agonistic signal toward other males. This study uses remote acoustic monitoring to analyze the presence of gunshots over a two-year period at two sites on the Scotian Shelf to determine if there is evidence that North Atlantic right whales may use these locations for breeding activities. Seasonal analyses at both locations indicate that gunshot sound production is highly seasonal, with an increase in the autumn. One site, Roseway West, had significantly more gunshot sounds overall and exhibited a clear diel trend in production of these signals at night. The other site, Emerald South, also showed a seasonal increase in gunshot production during the autumn, but did not show any significant diel trend. This difference in gunshot signal production at the two sites indicates variation either in the number or the behavior of whales at each location. The timing of the observed seasonal increase in gunshot sound production is consistent with the current understanding of the right whale breeding season, and our results demonstrate that detection of gunshots with remote acoustic monitoring can be a reliable way to track shifts in distribution and changes in acoustic behavior including possible mating activities. PMID:24646524

Remote acoustic monitoring of North Atlantic right whales (Eubalaena glacialis) reveals seasonal and diel variations in acoustic behavior.

PubMed

Matthews, Leanna P; McCordic, Jessica A; Parks, Susan E

2014-01-01

Remote acoustic monitoring is a non-invasive tool that can be used to study the distribution, behavior, and habitat use of sound-producing species. The North Atlantic right whale (Eubalaena glacialis) is an endangered baleen whale species that produces a variety of stereotyped acoustic signals. One of these signals, the "gunshot" sound, has only been recorded from adult male North Atlantic right whales and is thought to function for reproduction, either as reproductive advertisement for females or as an agonistic signal toward other males. This study uses remote acoustic monitoring to analyze the presence of gunshots over a two-year period at two sites on the Scotian Shelf to determine if there is evidence that North Atlantic right whales may use these locations for breeding activities. Seasonal analyses at both locations indicate that gunshot sound production is highly seasonal, with an increase in the autumn. One site, Roseway West, had significantly more gunshot sounds overall and exhibited a clear diel trend in production of these signals at night. The other site, Emerald South, also showed a seasonal increase in gunshot production during the autumn, but did not show any significant diel trend. This difference in gunshot signal production at the two sites indicates variation either in the number or the behavior of whales at each location. The timing of the observed seasonal increase in gunshot sound production is consistent with the current understanding of the right whale breeding season, and our results demonstrate that detection of gunshots with remote acoustic monitoring can be a reliable way to track shifts in distribution and changes in acoustic behavior including possible mating activities.

Brain Activation Patterns in Response to Conspecific and Heterospecific Social Acoustic Signals in Female Plainfin Midshipman Fish, Porichthys notatus.

PubMed

Mohr, Robert A; Chang, Yiran; Bhandiwad, Ashwin A; Forlano, Paul M; Sisneros, Joseph A

2018-01-01

While the peripheral auditory system of fish has been well studied, less is known about how the fish's brain and central auditory system process complex social acoustic signals. The plainfin midshipman fish, Porichthys notatus, has become a good species for investigating the neural basis of acoustic communication because the production and reception of acoustic signals is paramount for this species' reproductive success. Nesting males produce long-duration advertisement calls that females detect and localize among the noise in the intertidal zone to successfully find mates and spawn. How female midshipman are able to discriminate male advertisement calls from environmental noise and other acoustic stimuli is unknown. Using the immediate early gene product cFos as a marker for neural activity, we quantified neural activation of the ascending auditory pathway in female midshipman exposed to conspecific advertisement calls, heterospecific white seabass calls, or ambient environment noise. We hypothesized that auditory hindbrain nuclei would be activated by general acoustic stimuli (ambient noise and other biotic acoustic stimuli) whereas auditory neurons in the midbrain and forebrain would be selectively activated by conspecific advertisement calls. We show that neural activation in two regions of the auditory hindbrain, i.e., the rostral intermediate division of the descending octaval nucleus and the ventral division of the secondary octaval nucleus, did not differ via cFos immunoreactive (cFos-ir) activity when exposed to different acoustic stimuli. In contrast, female midshipman exposed to conspecific advertisement calls showed greater cFos-ir in the nucleus centralis of the midbrain torus semicircularis compared to fish exposed only to ambient noise. No difference in cFos-ir was observed in the torus semicircularis of animals exposed to conspecific versus heterospecific calls. However, cFos-ir was greater in two forebrain structures that receive auditory input, i

The acoustic communities: Definition, description and ecological role.

PubMed

Farina, Almo; James, Philip

2016-09-01

An acoustic community is defined as an aggregation of species that produces sound by using internal or extra-body sound-producing tools. Such communities occur in aquatic (freshwater and marine) and terrestrial environments. An acoustic community is the biophonic component of a soundtope and is characterized by its acoustic signature, which results from the distribution of sonic information associated with signal amplitude and frequency. Distinct acoustic communities can be described according to habitat, the frequency range of the acoustic signals, and the time of day or the season. Near and far fields can be identified empirically, thus the acoustic community can be used as a proxy for biodiversity richness. The importance of ecoacoustic research is rapidly growing due to the increasing awareness of the intrusion of anthropogenic sounds (technophonies) into natural and human-modified ecosystems and the urgent need to adopt more efficient predictive tools to compensate for the effects of climate change. The concept of an acoustic community provides an operational scale for a non-intrusive biodiversity survey and analysis that can be carried out using new passive audio recording technology, coupled with methods of vast data processing and storage. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Near- Source, Seismo-Acoustic Signals Accompanying a NASCAR Race at the Texas Motor Speedway

NASA Astrophysics Data System (ADS)

Stump, B. W.; Hayward, C.; Underwood, R.; Howard, J. E.; MacPhail, M. D.; Golden, P.; Endress, A.

2014-12-01

Near-source, seismo-acoustic observations provide a unique opportunity to characterize urban sources, remotely sense human activities including vehicular traffic and monitor large engineering structures. Energy separately coupled into the solid earth and atmosphere provides constraints on not only the location of these sources but also the physics of the generating process. Conditions and distances at which these observations can be made are dependent upon not only local geological conditions but also atmospheric conditions at the time of the observations. In order to address this range of topics, an empirical, seismo-acoustic study was undertaken in and around the Texas Motor Speedway in the Dallas-Ft. Worth area during the first week of April 2014 at which time a range of activities associated with a series of NASCAR races occurred. Nine, seismic sensors were deployed around the 1.5-mile track for purposes of documenting the direct-coupled seismic energy from the passage of the cars and other vehicles on the track. Six infrasound sensors were deployed on a rooftop in a rectangular array configuration designed to provide high frequency beam forming for acoustic signals. Finally, a five-element infrasound array was deployed outside the track in order to characterize how the signals propagate away from the sources in the near-source region. Signals recovered from within the track were able to track and characterize the motion of a variety of vehicles during the race weekend including individual racecars. Seismic data sampled at 1000 sps documented strong Doppler effects as the cars approached and moved away from individual sensors. There were faint seismic signals that arrived at seismic velocity but local acoustic to seismic coupling as supported by the acoustic observations generated the majority of seismic signals. Actual seismic ground motions were small as demonstrated by the dominance of regional seismic signals from a magnitude 4.0 earthquake that arrived at

Analyzing the Acoustic Beat with Mobile Devices

ERIC Educational Resources Information Center

Kuhn, Jochen; Vogt, Patrik; Hirth, Michael

2014-01-01

In this column, we have previously presented various examples of how physical relationships can be examined by analyzing acoustic signals using smartphones or tablet PCs. In this example, we will be exploring the acoustic phenomenon of small beats, which is produced by the overlapping of two tones with a low difference in frequency ?f. The…

The Vocal Repertoire of the Domesticated Zebra Finch: a Data Driven Approach to Decipher the Information-bearing Acoustic Features of Communication Signals

PubMed Central

Elie, Julie E.; Theunissen, Frédéric E.

2018-01-01

Although a universal code for the acoustic features of animal vocal communication calls may not exist, the thorough analysis of the distinctive acoustical features of vocalization categories is important not only to decipher the acoustical code for a specific species but also to understand the evolution of communication signals and the mechanisms used to produce and understand them. Here, we recorded more than 8,000 examples of almost all the vocalizations of the domesticated zebra finch, Taeniopygia guttata: vocalizations produced to establish contact, to form and maintain pair bonds, to sound an alarm, to communicate distress or to advertise hunger or aggressive intents. We characterized each vocalization type using complete representations that avoided any a priori assumptions on the acoustic code, as well as classical bioacoustics measures that could provide more intuitive interpretations. We then used these acoustical features to rigorously determine the potential information-bearing acoustical features for each vocalization type using both a novel regularized classifier and an unsupervised clustering algorithm. Vocalization categories are discriminated by the shape of their frequency spectrum and by their pitch saliency (noisy to tonal vocalizations) but not particularly by their fundamental frequency. Notably, the spectral shape of zebra finch vocalizations contains peaks or formants that vary systematically across categories and that would be generated by active control of both the vocal organ (source) and the upper vocal tract (filter). PMID:26581377

Theoretical detection threshold of the proton-acoustic range verification technique.

PubMed

Ahmad, Moiz; Xiang, Liangzhong; Yousefi, Siavash; Xing, Lei

2015-10-01

Range verification in proton therapy using the proton-acoustic signal induced in the Bragg peak was investigated for typical clinical scenarios. The signal generation and detection processes were simulated in order to determine the signal-to-noise limits. An analytical model was used to calculate the dose distribution and local pressure rise (per proton) for beams of different energy (100 and 160 MeV) and spot widths (1, 5, and 10 mm) in a water phantom. In this method, the acoustic waves propagating from the Bragg peak were generated by the general 3D pressure wave equation implemented using a finite element method. Various beam pulse widths (0.1-10 μs) were simulated by convolving the acoustic waves with Gaussian kernels. A realistic PZT ultrasound transducer (5 cm diameter) was simulated with a Butterworth bandpass filter with consideration of random noise based on a model of thermal noise in the transducer. The signal-to-noise ratio on a per-proton basis was calculated, determining the minimum number of protons required to generate a detectable pulse. The maximum spatial resolution of the proton-acoustic imaging modality was also estimated from the signal spectrum. The calculated noise in the transducer was 12-28 mPa, depending on the transducer central frequency (70-380 kHz). The minimum number of protons detectable by the technique was on the order of 3-30 × 10(6) per pulse, with 30-800 mGy dose per pulse at the Bragg peak. Wider pulses produced signal with lower acoustic frequencies, with 10 μs pulses producing signals with frequency less than 100 kHz. The proton-acoustic process was simulated using a realistic model and the minimal detection limit was established for proton-acoustic range validation. These limits correspond to a best case scenario with a single large detector with no losses and detector thermal noise as the sensitivity limiting factor. Our study indicated practical proton-acoustic range verification may be feasible with approximately 5 �

Adaptive fault feature extraction from wayside acoustic signals from train bearings

NASA Astrophysics Data System (ADS)

Zhang, Dingcheng; Entezami, Mani; Stewart, Edward; Roberts, Clive; Yu, Dejie

2018-07-01

Wayside acoustic detection of train bearing faults plays a significant role in maintaining safety in the railway transport system. However, the bearing fault information is normally masked by strong background noises and harmonic interferences generated by other components (e.g. axles and gears). In order to extract the bearing fault feature information effectively, a novel method called improved singular value decomposition (ISVD) with resonance-based signal sparse decomposition (RSSD), namely the ISVD-RSSD method, is proposed in this paper. A Savitzky-Golay (S-G) smoothing filter is used to filter singular vectors (SVs) in the ISVD method as an extension of the singular value decomposition (SVD) theorem. Hilbert spectrum entropy and a stepwise optimisation strategy are used to optimize the S-G filter's parameters. The RSSD method is able to nonlinearly decompose the wayside acoustic signal of a faulty train bearing into high and low resonance components, the latter of which contains bearing fault information. However, the high level of noise usually results in poor decomposition results from the RSSD method. Hence, the collected wayside acoustic signal must first be de-noised using the ISVD component of the ISVD-RSSD method. Next, the de-noised signal is decomposed by using the RSSD method. The obtained low resonance component is then demodulated with a Hilbert transform such that the bearing fault can be detected by observing Hilbert envelope spectra. The effectiveness of the ISVD-RSSD method is verified through both laboratory field-based experiments as described in the paper. The results indicate that the proposed method is superior to conventional spectrum analysis and ensemble empirical mode decomposition methods.

The acoustic adaptation hypothesis in a widely distributed South American frog: Southernmost signals propagate better.

PubMed

Velásquez, Nelson A; Moreno-Gómez, Felipe N; Brunetti, Enzo; Penna, Mario

2018-05-03

Animal communication occurs in environments that affect the properties of signals as they propagate from senders to receivers. We studied the geographic variation of the advertisement calls of male Pleurodema thaul individuals from eight localities in Chile. Furthermore, by means of signal propagation experiments, we tested the hypothesis that local calls are better transmitted and less degraded than foreign calls (i.e. acoustic adaptation hypothesis). Overall, the advertisement calls varied greatly along the distribution of P. thaul in Chile, and it was possible to discriminate localities grouped into northern, central and southern stocks. Propagation distance affected signal amplitude and spectral degradation in all localities, but temporal degradation was only affected by propagation distance in one out of seven localities. Call origin affected signal amplitude in five out of seven localities and affected spectral and temporal degradation in six out of seven localities. In addition, in northern localities, local calls degraded more than foreign calls, and in southern localities the opposite was observed. The lack of a strict optimal relationship between signal characteristics and environment indicates partial concordance with the acoustic adaptation hypothesis. Inter-population differences in selectivity for call patterns may compensate for such environmental constraints on acoustic communication.

Ultrasound-modulated optical tomography with intense acoustic bursts.

PubMed

Zemp, Roger J; Kim, Chulhong; Wang, Lihong V

2007-04-01

Ultrasound-modulated optical tomography (UOT) detects ultrasonically modulated light to spatially localize multiply scattered photons in turbid media with the ultimate goal of imaging the optical properties in living subjects. A principal challenge of the technique is weak modulated signal strength. We discuss ways to push the limits of signal enhancement with intense acoustic bursts while conforming to optical and ultrasonic safety standards. A CCD-based speckle-contrast detection scheme is used to detect acoustically modulated light by measuring changes in speckle statistics between ultrasound-on and ultrasound-off states. The CCD image capture is synchronized with the ultrasound burst pulse sequence. Transient acoustic radiation force, a consequence of bursts, is seen to produce slight signal enhancement over pure ultrasonic-modulation mechanisms for bursts and CCD exposure times of the order of milliseconds. However, acoustic radiation-force-induced shear waves are launched away from the acoustic sample volume, which degrade UOT spatial resolution. By time gating the CCD camera to capture modulated light before radiation force has an opportunity to accumulate significant tissue displacement, we reduce the effects of shear-wave image degradation, while enabling very high signal-to-noise ratios. Additionally, we maintain high-resolution images representative of optical and not mechanical contrast. Signal-to-noise levels are sufficiently high so as to enable acquisition of 2D images of phantoms with one acoustic burst per pixel.

Acoustic signals of baby black caimans.

PubMed

Vergne, Amélie L; Aubin, Thierry; Taylor, Peter; Mathevon, Nicolas

2011-12-01

In spite of the importance of crocodilian vocalizations for the understanding of the evolution of sound communication in Archosauria and due to the small number of experimental investigations, information concerning the vocal world of crocodilians is limited. By studying black caimans Melanosuchus niger in their natural habitat, here we supply the experimental evidence that juvenile crocodilians can use a graded sound system in order to elicit adapted behavioral responses from their mother and siblings. By analyzing the acoustic structure of calls emitted in two different situations ('undisturbed context', during which spontaneous calls of juvenile caimans were recorded without perturbing the group, and a simulated 'predator attack', during which calls were recorded while shaking juveniles) and by testing their biological relevance through playback experiments, we reveal the existence of two functionally different types of juvenile calls that produce a different response from the mother and other siblings. Young black caimans can thus modulate the structure of their vocalizations along an acoustic continuum as a function of the emission context. Playback experiments show that both mother and juveniles discriminate between these 'distress' and 'contact' calls. Acoustic communication is thus an important component mediating relationships within family groups in caimans as it is in birds, their archosaurian relatives. Although probably limited, the vocal repertoire of young crocodilians is capable of transmitting the information necessary for allowing siblings and mother to modulate their behavior. Copyright © 2011 Elsevier GmbH. All rights reserved.

The effect of artificial rain on backscattered acoustic signal: first measurements

NASA Astrophysics Data System (ADS)

Titchenko, Yuriy; Karaev, Vladimir; Meshkov, Evgeny; Goldblat, Vladimir

The problem of rain influencing on a characteristics of backscattered ultrasonic and microwave signal by water surface is considered. The rain influence on backscattering process of electromagnetic waves was investigated in laboratory and field experiments, for example [1-3]. Raindrops have a significant impact on backscattering of microwave and influence on wave spectrum measurement accuracy by string wave gauge. This occurs due to presence of raindrops in atmosphere and modification of the water surface. For measurements of water surface characteristics during precipitation we propose to use an acoustic system. This allows us obtaining of the water surface parameters independently on precipitation in atmosphere. The measurements of significant wave height of water surface using underwater acoustical systems are well known [4, 5]. Moreover, the variance of orbital velocity can be measure using these systems. However, these methods cannot be used for measurements of slope variance and the other second statistical moments of water surface that required for analyzing the radar backscatter signal. An original design Doppler underwater acoustic wave gauge allows directly measuring the surface roughness characteristics that affect on electromagnetic waves backscattering of the same wavelength [6]. Acoustic wave gauge is Doppler ultrasonic sonar which is fixed near the bottom on the floating disk. Measurements are carried out at vertically orientation of sonar antennas towards water surface. The first experiments were conducted with the first model of an acoustic wave gauge. The acoustic wave gauge (8 mm wavelength) is equipped with a transceiving antenna with a wide symmetrical antenna pattern. The gauge allows us to measure Doppler spectrum and cross section of backscattered signal. Variance of orbital velocity vertical component can be retrieved from Doppler spectrum with high accuracy. The result of laboratory and field experiments during artificial rain is presented

Acousto-Optic Interaction in Surface Acoustic Waves and Its Application to Real Time Signal Processing.

DTIC Science & Technology

1977-12-30

ACOUSTO - OPTIC INTERACTION IN SURFACE ACOUSTIC WAVES AND ITS APP--ETC(U) DEC 77 0 SCHUMER, P DAS NOOOIJ -75-C-0772 NCLASSIFIED MA-ONR-30 Nt.EE E’h...CHART NAT*NAL BUREAU OF STANDARDS 1-63- ACOUSTO - OPTIC INTERACTION IN SURFACE ACOUSTIC WAVES AND ITS APPLICATION TO REAL TIME SIGNAL PROCESSING By 00 D... Acousto - optics , Integrated optics, Optical Signal Processing. 20. AbSKTRACT (Continue an reverse side it neceary and idewnt& by block mum ber) The

Search for acoustic signals from high energy cascades

NASA Technical Reports Server (NTRS)

Bell, R.; Bowen, T.

1985-01-01

High energy cosmic ray secondaries can be detected by means of the cascades they produce when they pass through matter. When the charged particles of these cascades ionize the matter they are traveling through, the heat produced and resulting thermal expansion causes a thermoacoustic wave. These sound waves travel at about one hundred-thousandth the speed of light, and should allow an array of acoustic transducers to resolve structure in the cascade to about 1 cm without high speed electronics or segmentation of the detector.

Acoustic Signal Processing for Pipe Condition Assessment (WaterRF Report 4360)

EPA Science Inventory

Unique to prestressed concrete cylinder pipe (PCCP), individual wire breaks create an excitation in the pipe wall that may vary in response to the remaining compression of the pipe core. This project was designed to improve acoustic signal processing for pipe condition assessment...

System and method for investigating sub-surface features of a rock formation with acoustic sources generating conical broadcast signals

DOEpatents

Vu, Cung Khac; Skelt, Christopher; Nihei, Kurt; Johnson, Paul A.; Guyer, Robert; Ten Cate, James A.; Le Bas, Pierre -Yves; Larmat, Carene S.

2015-08-18

A method of interrogating a formation includes generating a conical acoustic signal, at a first frequency--a second conical acoustic signal at a second frequency each in the between approximately 500 Hz and 500 kHz such that the signals intersect in a desired intersection volume outside the borehole. The method further includes receiving, a difference signal returning to the borehole resulting from a non-linear mixing of the signals in a mixing zone within the intersection volume.

Spatial acoustic signal processing for immersive communication

NASA Astrophysics Data System (ADS)

Atkins, Joshua

Computing is rapidly becoming ubiquitous as users expect devices that can augment and interact naturally with the world around them. In these systems it is necessary to have an acoustic front-end that is able to capture and reproduce natural human communication. Whether the end point is a speech recognizer or another human listener, the reduction of noise, reverberation, and acoustic echoes are all necessary and complex challenges. The focus of this dissertation is to provide a general method for approaching these problems using spherical microphone and loudspeaker arrays.. In this work, a theory of capturing and reproducing three-dimensional acoustic fields is introduced from a signal processing perspective. In particular, the decomposition of the spatial part of the acoustic field into an orthogonal basis of spherical harmonics provides not only a general framework for analysis, but also many processing advantages. The spatial sampling error limits the upper frequency range with which a sound field can be accurately captured or reproduced. In broadband arrays, the cost and complexity of using multiple transducers is an issue. This work provides a flexible optimization method for determining the location of array elements to minimize the spatial aliasing error. The low frequency array processing ability is also limited by the SNR, mismatch, and placement error of transducers. To address this, a robust processing method is introduced and used to design a reproduction system for rendering over arbitrary loudspeaker arrays or binaurally over headphones. In addition to the beamforming problem, the multichannel acoustic echo cancellation (MCAEC) issue is also addressed. A MCAEC must adaptively estimate and track the constantly changing loudspeaker-room-microphone response to remove the sound field presented over the loudspeakers from that captured by the microphones. In the multichannel case, the system is overdetermined and many adaptive schemes fail to converge to

Attenuation of the Acoustic Signal Propagating Through a Bubbly Liquid Layer

NASA Astrophysics Data System (ADS)

Gubaidullin, D. A.; Nikiforov, A. A.

2018-01-01

The acoustic signal dynamics in a five-layer medium containing two liquid layers with polydisperse gas bubbles has been investigated. Calculations have been made for the interaction between the pulse perturbation of smallamplitude pressure and a multilayer sample containing two layers of industrial gel with polydisperse air bubbles. It has been shown that a small content of bubbles (about 0.1 vol. %) in a thin gel layer decreases tenfold or more the amplitude of acoustic waves with frequencies close to the resonance frequency of natural oscillations of bubbles. There are frequency ranges thereby where the influence of the bubbly layer is insignificant.

Theoretical detection threshold of the proton-acoustic range verification technique

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

Ahmad, Moiz; Yousefi, Siavash; Xing, Lei, E-mail: lei@stanford.edu

2015-10-15

Purpose: Range verification in proton therapy using the proton-acoustic signal induced in the Bragg peak was investigated for typical clinical scenarios. The signal generation and detection processes were simulated in order to determine the signal-to-noise limits. Methods: An analytical model was used to calculate the dose distribution and local pressure rise (per proton) for beams of different energy (100 and 160 MeV) and spot widths (1, 5, and 10 mm) in a water phantom. In this method, the acoustic waves propagating from the Bragg peak were generated by the general 3D pressure wave equation implemented using a finite element method.more » Various beam pulse widths (0.1–10 μs) were simulated by convolving the acoustic waves with Gaussian kernels. A realistic PZT ultrasound transducer (5 cm diameter) was simulated with a Butterworth bandpass filter with consideration of random noise based on a model of thermal noise in the transducer. The signal-to-noise ratio on a per-proton basis was calculated, determining the minimum number of protons required to generate a detectable pulse. The maximum spatial resolution of the proton-acoustic imaging modality was also estimated from the signal spectrum. Results: The calculated noise in the transducer was 12–28 mPa, depending on the transducer central frequency (70–380 kHz). The minimum number of protons detectable by the technique was on the order of 3–30 × 10{sup 6} per pulse, with 30–800 mGy dose per pulse at the Bragg peak. Wider pulses produced signal with lower acoustic frequencies, with 10 μs pulses producing signals with frequency less than 100 kHz. Conclusions: The proton-acoustic process was simulated using a realistic model and the minimal detection limit was established for proton-acoustic range validation. These limits correspond to a best case scenario with a single large detector with no losses and detector thermal noise as the sensitivity limiting factor. Our study indicated practical proton-acoustic

Theoretical detection threshold of the proton-acoustic range verification technique

PubMed Central

Ahmad, Moiz; Xiang, Liangzhong; Yousefi, Siavash; Xing, Lei

2015-01-01

Purpose: Range verification in proton therapy using the proton-acoustic signal induced in the Bragg peak was investigated for typical clinical scenarios. The signal generation and detection processes were simulated in order to determine the signal-to-noise limits. Methods: An analytical model was used to calculate the dose distribution and local pressure rise (per proton) for beams of different energy (100 and 160 MeV) and spot widths (1, 5, and 10 mm) in a water phantom. In this method, the acoustic waves propagating from the Bragg peak were generated by the general 3D pressure wave equation implemented using a finite element method. Various beam pulse widths (0.1–10 μs) were simulated by convolving the acoustic waves with Gaussian kernels. A realistic PZT ultrasound transducer (5 cm diameter) was simulated with a Butterworth bandpass filter with consideration of random noise based on a model of thermal noise in the transducer. The signal-to-noise ratio on a per-proton basis was calculated, determining the minimum number of protons required to generate a detectable pulse. The maximum spatial resolution of the proton-acoustic imaging modality was also estimated from the signal spectrum. Results: The calculated noise in the transducer was 12–28 mPa, depending on the transducer central frequency (70–380 kHz). The minimum number of protons detectable by the technique was on the order of 3–30 × 106 per pulse, with 30–800 mGy dose per pulse at the Bragg peak. Wider pulses produced signal with lower acoustic frequencies, with 10 μs pulses producing signals with frequency less than 100 kHz. Conclusions: The proton-acoustic process was simulated using a realistic model and the minimal detection limit was established for proton-acoustic range validation. These limits correspond to a best case scenario with a single large detector with no losses and detector thermal noise as the sensitivity limiting factor. Our study indicated practical proton-acoustic range

Measuring acoustic habitats

PubMed Central

Merchant, Nathan D; Fristrup, Kurt M; Johnson, Mark P; Tyack, Peter L; Witt, Matthew J; Blondel, Philippe; Parks, Susan E

2015-01-01

1. Many organisms depend on sound for communication, predator/prey detection and navigation. The acoustic environment can therefore play an important role in ecosystem dynamics and evolution. A growing number of studies are documenting acoustic habitats and their influences on animal development, behaviour, physiology and spatial ecology, which has led to increasing demand for passive acoustic monitoring (PAM) expertise in the life sciences. However, as yet, there has been no synthesis of data processing methods for acoustic habitat monitoring, which presents an unnecessary obstacle to would-be PAM analysts. 2. Here, we review the signal processing techniques needed to produce calibrated measurements of terrestrial and aquatic acoustic habitats. We include a supplemental tutorial and template computer codes in matlab and r, which give detailed guidance on how to produce calibrated spectrograms and statistical analyses of sound levels. Key metrics and terminology for the characterisation of biotic, abiotic and anthropogenic sound are covered, and their application to relevant monitoring scenarios is illustrated through example data sets. To inform study design and hardware selection, we also include an up-to-date overview of terrestrial and aquatic PAM instruments. 3. Monitoring of acoustic habitats at large spatiotemporal scales is becoming possible through recent advances in PAM technology. This will enhance our understanding of the role of sound in the spatial ecology of acoustically sensitive species and inform spatial planning to mitigate the rising influence of anthropogenic noise in these ecosystems. As we demonstrate in this work, progress in these areas will depend upon the application of consistent and appropriate PAM methodologies. PMID:25954500

Measuring acoustic habitats.

PubMed

Merchant, Nathan D; Fristrup, Kurt M; Johnson, Mark P; Tyack, Peter L; Witt, Matthew J; Blondel, Philippe; Parks, Susan E

2015-03-01

1. Many organisms depend on sound for communication, predator/prey detection and navigation. The acoustic environment can therefore play an important role in ecosystem dynamics and evolution. A growing number of studies are documenting acoustic habitats and their influences on animal development, behaviour, physiology and spatial ecology, which has led to increasing demand for passive acoustic monitoring (PAM) expertise in the life sciences. However, as yet, there has been no synthesis of data processing methods for acoustic habitat monitoring, which presents an unnecessary obstacle to would-be PAM analysts. 2. Here, we review the signal processing techniques needed to produce calibrated measurements of terrestrial and aquatic acoustic habitats. We include a supplemental tutorial and template computer codes in matlab and r, which give detailed guidance on how to produce calibrated spectrograms and statistical analyses of sound levels. Key metrics and terminology for the characterisation of biotic, abiotic and anthropogenic sound are covered, and their application to relevant monitoring scenarios is illustrated through example data sets. To inform study design and hardware selection, we also include an up-to-date overview of terrestrial and aquatic PAM instruments. 3. Monitoring of acoustic habitats at large spatiotemporal scales is becoming possible through recent advances in PAM technology. This will enhance our understanding of the role of sound in the spatial ecology of acoustically sensitive species and inform spatial planning to mitigate the rising influence of anthropogenic noise in these ecosystems. As we demonstrate in this work, progress in these areas will depend upon the application of consistent and appropriate PAM methodologies.

Active acoustic interference elicits echolocation changes in heterospecific bats.

PubMed

Jones, Te K; Wohlgemuth, Melville J; Conner, William E

2018-06-27

Echolocating bats often forage in the presence of both conspecific and heterospecific individuals who have the potential to produce acoustic interference. Recent studies have shown that at least one bat species, the Brazilian free-tailed bat ( Tadarida brasiliensis ), produces specialized social signals that disrupt the sonar of conspecific competitors. We herein discuss the differences between passive and active jamming signals and test whether heterospecific jamming occurs in species overlapping spatiotemporally as well as whether such interference elicits a jamming avoidance response (JAR). We compare the capture rates of tethered moths and the echolocation parameters of big brown bats ( Eptesicus fuscus ) challenged with the playback of the jamming signal normally produced by Brazilian free-tailed bats and playback of deconstructed versions of this signal. There were no differences in the capture rates of targets with and without the jamming signal although significant changes in both spectral and temporal features of the bats' echolocation were observed. These changes are consistent with improvements of the signal-to-noise ratio in the presence of acoustic interference. Accordingly, we propose to expand the traditional definition of the JAR, stating that echolocation changes in response to interference should decrease similarity between the two signals, to include any change that increases the ability to separate returning echoes from active jamming stimuli originating from conspecific and heterospecific organisms. Flexibility in echolocation is an important characteristic for overcoming various forms of acoustic interference and may serve a purpose in interspecific interactions as well as intraspecific ones. © 2018. Published by The Company of Biologists Ltd.

Geo-Acoustic Doppler Spectroscopy: A Novel Acoustic Technique For Surveying The Seabed

NASA Astrophysics Data System (ADS)

Buckingham, Michael J.

2010-09-01

An acoustic inversion technique, known as Geo-Acoustic Doppler Spectroscopy, has recently been developed for estimating the geo-acoustic parameters of the seabed in shallow water. The technique is unusual in that it utilizes a low-flying, propeller-driven light aircraft as an acoustic source. Both the engine and propeller produce sound and, since they are rotating sources, the acoustic signature of each takes the form of a sequence of narrow-band harmonics. Although the coupling of the harmonics across the air-sea interface is inefficient, due to the large impedance mismatch between air and water, sufficient energy penetrates the sea surface to provide a useable underwater signal at sensors either in the water column or buried in the sediment. The received signals, which are significantly Doppler shifted due to the motion of the aircraft, will have experienced a number of reflections from the seabed and thus they contain information about the sediment. A geo-acoustic inversion of the Doppler-shifted modes associated with each harmonic yields an estimate of the sound speed in the sediment; and, once the sound speed has been determined, the known correlations between it and the remaining geo-acoustic parameters allow all of the latter to be computed. This inversion technique has been applied to aircraft data collected in the shallow water north of Scripps pier, returning values of the sound speed, shear speed, porosity, density and grain size that are consistent with the known properties of the sandy sediment in the channel.

Dual fiber Bragg gratings configuration-based fiber acoustic sensor for low-frequency signal detection

NASA Astrophysics Data System (ADS)

Yang, Dong; Wang, Shun; Lu, Ping; Liu, Deming

2014-11-01

We propose and fabricate a new type fiber acoustic sensor based on dual fiber Bragg gratings (FBGs) configuration. The acoustic sensor head is constructed by putting the sensing cells enclosed in an aluminum cylinder space built by two Cband FBGs and a titanium diaphragm of 50 um thickness. One end of each FBG is longitudinally adhered to the diaphragm by UV glue. Both of the two FBGs are employed for reflecting light. The dual FBGs play roles not only as signal transmission system but also as sensing component, and they demodulate each other's optical signal mutually during the measurement. Both of the two FBGs are pre-strained and the output optical power experiences fluctuation in a linear relationship along with a variation of axial strain and surrounding acoustic interference. So a precise approach to measure the frequency and sound pressure of the acoustic disturbance is achieved. Experiments are performed and results show that a relatively flat frequency response in a range from 200 Hz to 1 kHz with the average signal-to-noise ratio (SNR) above 21 dB is obtained. The maximum sound pressure sensitivity of 11.35mV/Pa is achieved with the Rsquared value of 0.99131 when the sound pressure in the range of 87.7-106.6dB. It has potential applications in low frequency signal detection. Owing to its direct self-demodulation method, the sensing system reveals the advantages of easy to demodulate, good temperature stability and measurement reliability. Besides, performance of the proposed sensor could be improved by optimizing the parameters of the sensor, especially the diaphragm.

Acoustic Levitation Containerless Processing

NASA Technical Reports Server (NTRS)

Whymark, R. R.; Rey, C. A.

1985-01-01

This research program consists of the development of acoustic containerless processing systems with applications in the areas of research in material sciences, as well as the production of new materials, solid forms with novel and unusual microstructures, fusion target spheres, and improved optical fibers. Efforts have been focused on the containerless processing at high temperatures for producing new kinds of glasses. Also, some development has occurred in the areas of containerlessly supporting liquids at room temperature, with applications in studies of fluid dynamics, potential undercooling of liquids, etc. The high temperature area holds the greatest promise for producing new kinds of glasses and ceramics, new alloys, and possibly unusual structural shapes, such as very uniform hollow glass shells for fusion target applications. High temperature acoustic levitation required for containerless processing has been demonstrated in low-g environments as well as in ground-based experiments. Future activities include continued development of the signals axis acoustic levitator.

The acoustic features of human laughter

NASA Astrophysics Data System (ADS)

Bachorowski, Jo-Anne; Owren, Michael J.

2002-05-01

Remarkably little is known about the acoustic features of laughter, despite laughter's ubiquitous role in human vocal communication. Outcomes are described for 1024 naturally produced laugh bouts recorded from 97 young adults. Acoustic analysis focused on temporal characteristics, production modes, source- and filter-related effects, and indexical cues to laugher sex and individual identity. The results indicate that laughter is a remarkably complex vocal signal, with evident diversity in both production modes and fundamental frequency characteristics. Also of interest was finding a consistent lack of articulation effects in supralaryngeal filtering. Outcomes are compared to previously advanced hypotheses and conjectures about this species-typical vocal signal.

Modern Techniques in Acoustical Signal and Image Processing

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

Candy, J V

2002-04-04

Acoustical signal processing problems can lead to some complex and intricate techniques to extract the desired information from noisy, sometimes inadequate, measurements. The challenge is to formulate a meaningful strategy that is aimed at performing the processing required even in the face of uncertainties. This strategy can be as simple as a transformation of the measured data to another domain for analysis or as complex as embedding a full-scale propagation model into the processor. The aims of both approaches are the same--to extract the desired information and reject the extraneous, that is, develop a signal processing scheme to achieve thismore » goal. In this paper, we briefly discuss this underlying philosophy from a ''bottom-up'' approach enabling the problem to dictate the solution rather than visa-versa.« less

Turboprop and rotary-wing aircraft flight parameter estimation using both narrow-band and broadband passive acoustic signal-processing methods.

PubMed

Ferguson, B G; Lo, K W

2000-10-01

Flight parameter estimation methods for an airborne acoustic source can be divided into two categories, depending on whether the narrow-band lines or the broadband component of the received signal spectrum is processed to estimate the flight parameters. This paper provides a common framework for the formulation and test of two flight parameter estimation methods: one narrow band, the other broadband. The performances of the two methods are evaluated by applying them to the same acoustic data set, which is recorded by a planar array of passive acoustic sensors during multiple transits of a turboprop fixed-wing aircraft and two types of rotary-wing aircraft. The narrow-band method, which is based on a kinematic model that assumes the source travels in a straight line at constant speed and altitude, requires time-frequency analysis of the acoustic signal received by a single sensor during each aircraft transit. The broadband method is based on the same kinematic model, but requires observing the temporal variation of the differential time of arrival of the acoustic signal at each pair of sensors that comprises the planar array. Generalized cross correlation of each pair of sensor outputs using a cross-spectral phase transform prefilter provides instantaneous estimates of the differential times of arrival of the signal as the acoustic wavefront traverses the array.

A methodology to condition distorted acoustic emission signals to identify fracture timing from human cadaver spine impact tests.

PubMed

Arun, Mike W J; Yoganandan, Narayan; Stemper, Brian D; Pintar, Frank A

2014-12-01

While studies have used acoustic sensors to determine fracture initiation time in biomechanical studies, a systematic procedure is not established to process acoustic signals. The objective of the study was to develop a methodology to condition distorted acoustic emission data using signal processing techniques to identify fracture initiation time. The methodology was developed from testing a human cadaver lumbar spine column. Acoustic sensors were glued to all vertebrae, high-rate impact loading was applied, load-time histories were recorded (load cell), and fracture was documented using CT. Compression fracture occurred to L1 while other vertebrae were intact. FFT of raw voltage-time traces were used to determine an optimum frequency range associated with high decibel levels. Signals were bandpass filtered in this range. Bursting pattern was found in the fractured vertebra while signals from other vertebrae were silent. Bursting time was associated with time of fracture initiation. Force at fracture was determined using this time and force-time data. The methodology is independent of selecting parameters a priori such as fixing a voltage level(s), bandpass frequency and/or using force-time signal, and allows determination of force based on time identified during signal processing. The methodology can be used for different body regions in cadaver experiments. Copyright © 2014 Elsevier Ltd. All rights reserved.

Digital signal processing at Bell Labs-Foundations for speech and acoustics research

NASA Astrophysics Data System (ADS)

Rabiner, Lawrence R.

2004-05-01

Digital signal processing (DSP) is a fundamental tool for much of the research that has been carried out of Bell Labs in the areas of speech and acoustics research. The fundamental bases for DSP include the sampling theorem of Nyquist, the method for digitization of analog signals by Shannon et al., methods of spectral analysis by Tukey, the cepstrum by Bogert et al., and the FFT by Tukey (and Cooley of IBM). Essentially all of these early foundations of DSP came out of the Bell Labs Research Lab in the 1930s, 1940s, 1950s, and 1960s. This fundamental research was motivated by fundamental applications (mainly in the areas of speech, sonar, and acoustics) that led to novel design methods for digital filters (Kaiser, Golden, Rabiner, Schafer), spectrum analysis methods (Rabiner, Schafer, Allen, Crochiere), fast convolution methods based on the FFT (Helms, Bergland), and advanced digital systems used to implement telephony channel banks (Jackson, McDonald, Freeny, Tewksbury). This talk summarizes the key contributions to DSP made at Bell Labs, and illustrates how DSP was utilized in the areas of speech and acoustics research. It also shows the vast, worldwide impact of this DSP research on modern consumer electronics.

Lattice Boltzmann modeling to explain volcano acoustic source.

PubMed

Brogi, Federico; Ripepe, Maurizio; Bonadonna, Costanza

2018-06-22

Acoustic pressure is largely used to monitor explosive activity at volcanoes and has become one of the most promising technique to monitor volcanoes also at large scale. However, no clear relation between the fluid dynamics of explosive eruptions and the associated acoustic signals has yet been defined. Linear acoustic has been applied to derive source parameters in the case of strong explosive eruptions which are well-known to be driven by large overpressure of the magmatic fluids. Asymmetric acoustic waveforms are generally considered as the evidence for supersonic explosive dynamics also for small explosive regimes. We have used Lattice-Boltzmann modeling of the eruptive fluid dynamics to analyse the acoustic wavefield produced by different flow regimes. We demonstrate that acoustic waveform well reproduces the flow dynamics of a subsonic fluid injection related to discrete explosive events. Different volumetric flow rate, at low-Mach regimes, can explain both the observed symmetric and asymmetric waveform. Hence, asymmetric waveforms are not necessarily related to the shock/supersonic fluid dynamics of the source. As a result, we highlight an ambiguity in the general interpretation of volcano acoustic signals for the retrieval of key eruption source parameters, necessary for a reliable volcanic hazard assessment.

Analysis of acoustic emission cumulative signal strength of steel fibre reinforced concrete (SFRC) beams strengthened with carbon fibre reinforced polymer (CFRP)

NASA Astrophysics Data System (ADS)

Abdul Hakeem, Z.; Noorsuhada, M. N.; Azmi, I.; Noor Syafeekha, M. S.; Soffian Noor, M. S.

2017-12-01

In this study, steel fibre reinforced concrete (SFRC) beams strengthened with carbon fibre reinforced polymer (CFRP) were investigated using acoustic emission (AE) technique. Three beams with dimension of 150 mm width, 200 mm depth and 1500 mm length were fabricated. The results generated from AE parameters were analysed as well as signal strength and cumulative signal strength. Three relationships were produced namely load versus deflection, signal strength versus time and cumulative signal strength with respect to time. Each relationship indicates significant physical behaviour as the crack propagated in the beams. It is found that an addition of steel fibre in the concrete mix and strengthening of CFRP increase the ultimate load of the beam and the activity of signal strength. Moreover, the highest signal strength generated can be identified. From the study, the occurrence of crack in the beam can be predicted using AE signal strength.

[Perception of emotional intonation of noisy speech signal with different acoustic parameters by adults of different age and gender].

PubMed

Dmitrieva, E S; Gel'man, V Ia

2011-01-01

The listener-distinctive features of recognition of different emotional intonations (positive, negative and neutral) of male and female speakers in the presence or absence of background noise were studied in 49 adults aged 20-79 years. In all the listeners noise produced the most pronounced decrease in recognition accuracy for positive emotional intonation ("joy") as compared to other intonations, whereas it did not influence the recognition accuracy of "anger" in 65-79-year-old listeners. The higher emotion recognition rates of a noisy signal were observed for speech emotional intonations expressed by female speakers. Acoustic characteristics of noisy and clear speech signals underlying perception of speech emotional prosody were found for adult listeners of different age and gender.

Mapping thunder sources by inverting acoustic and electromagnetic observations

NASA Astrophysics Data System (ADS)

Anderson, J. F.; Johnson, J. B.; Arechiga, R. O.; Thomas, R. J.

2014-12-01

We present a new method of locating current flow in lightning strikes by inversion of thunder recordings constrained by Lightning Mapping Array observations. First, radio frequency (RF) pulses are connected to reconstruct conductive channels created by leaders. Then, acoustic signals that would be produced by current flow through each channel are forward modeled. The recorded thunder is considered to consist of a weighted superposition of these acoustic signals. We calculate the posterior distribution of acoustic source energy for each channel with a Markov Chain Monte Carlo inversion that fits power envelopes of modeled and recorded thunder; these results show which parts of the flash carry current and produce thunder. We examine the effects of RF pulse location imprecision and atmospheric winds on quality of results and apply this method to several lightning flashes over the Magdalena Mountains in New Mexico, USA. This method will enable more detailed study of lightning phenomena by allowing researchers to map current flow in addition to leader propagation.

Acoustic emission signal processing for rolling bearing running state assessment using compressive sensing

NASA Astrophysics Data System (ADS)

Liu, Chang; Wu, Xing; Mao, Jianlin; Liu, Xiaoqin

2017-07-01

In the signal processing domain, there has been growing interest in using acoustic emission (AE) signals for the fault diagnosis and condition assessment instead of vibration signals, which has been advocated as an effective technique for identifying fracture, crack or damage. The AE signal has high frequencies up to several MHz which can avoid some signals interference, such as the parts of bearing (i.e. rolling elements, ring and so on) and other rotating parts of machine. However, acoustic emission signal necessitates advanced signal sampling capabilities and requests ability to deal with large amounts of sampling data. In this paper, compressive sensing (CS) is introduced as a processing framework, and then a compressive features extraction method is proposed. We use it for extracting the compressive features from compressively-sensed data directly, and also prove the energy preservation properties. First, we study the AE signals under the CS framework. The sparsity of AE signal of the rolling bearing is checked. The observation and reconstruction of signal is also studied. Second, we present a method of extraction AE compressive feature (AECF) from compressively-sensed data directly. We demonstrate the energy preservation properties and the processing of the extracted AECF feature. We assess the running state of the bearing using the AECF trend. The AECF trend of the running state of rolling bearings is consistent with the trend of traditional features. Thus, the method is an effective way to evaluate the running trend of rolling bearings. The results of the experiments have verified that the signal processing and the condition assessment based on AECF is simpler, the amount of data required is smaller, and the amount of computation is greatly reduced.

Acoustical standards in engineering acoustics

NASA Astrophysics Data System (ADS)

Burkhard, Mahlon D.

2004-05-01

The Engineering Acoustics Technical Committee is concerned with the evolution and improvement of acoustical techniques and apparatus, and with the promotion of new applications of acoustics. As cited in the Membership Directory and Handbook (2002), the interest areas include transducers and arrays; underwater acoustic systems; acoustical instrumentation and monitoring; applied sonics, promotion of useful effects, information gathering and transmission; audio engineering; acoustic holography and acoustic imaging; acoustic signal processing (equipment and techniques); and ultrasound and infrasound. Evident connections between engineering and standards are needs for calibration, consistent terminology, uniform presentation of data, reference levels, or design targets for product development. Thus for the acoustical engineer standards are both a tool for practices, for communication, and for comparison of his efforts with those of others. Development of many standards depends on knowledge of the way products are put together for the market place and acoustical engineers provide important input to the development of standards. Acoustical engineers and members of the Engineering Acoustics arm of the Society both benefit from and contribute to the Acoustical Standards of the Acoustical Society.

Amplitude sorting of oscillatory burst signals by sampling

DOEpatents

Davis, Thomas J.

1977-01-01

A method and apparatus for amplitude sorting of oscillatory burst signals is described in which the burst signal is detected to produce a burst envelope signal and an intermediate or midportion of such envelope signal is sampled to provide a sample pulse output. The height of the sample pulse is proportional to the amplitude of the envelope signal and to the maximum burst signal amplitude. The sample pulses are fed to a pulse height analyzer for sorting. The present invention is used in an acoustic emission testing system to convert the amplitude of the acoustic emission burst signals into sample pulse heights which are measured by a pulse height analyzer for sorting the pulses in groups according to their height in order to identify the material anomalies in the test material which emit the acoustic signals.

Waveform Based Acoustic Emission Detection and Location of Matrix Cracking in Composites

NASA Technical Reports Server (NTRS)

Prosser, W. H.

1995-01-01

The operation of damage mechanisms in a material or structure under load produces transient acoustic waves. These acoustic waves are known as acoustic emission (AE). In composites they can be caused by a variety of sources including matrix cracking, fiber breakage, and delamination. AE signals can be detected and analyzed to determine the location of the acoustic source by triangulation. Attempts are also made to analyze the signals to determine the type and severity of the damage mechanism. AE monitoring has been widely used for both laboratory studies of materials, and for testing the integrity of structures in the field. In this work, an advanced, waveform based AE system was used in a study of transverse matrix cracking in cross-ply graphite/epoxy laminates. This AE system featured broad band, high fidelity sensors, and high capture rate digital acquisition and storage of acoustic signals. In addition, analysis techniques based on plate wave propagation models were employed. These features provided superior source location and noise rejection capabilities.

Acoustic localization of triggered lightning

NASA Astrophysics Data System (ADS)

Arechiga, Rene O.; Johnson, Jeffrey B.; Edens, Harald E.; Thomas, Ronald J.; Rison, William

2011-05-01

We use acoustic (3.3-500 Hz) arrays to locate local (<20 km) thunder produced by triggered lightning in the Magdalena Mountains of central New Mexico. The locations of the thunder sources are determined by the array back azimuth and the elapsed time since discharge of the lightning flash. We compare the acoustic source locations with those obtained by the Lightning Mapping Array (LMA) from Langmuir Laboratory, which is capable of accurately locating the lightning channels. To estimate the location accuracy of the acoustic array we performed Monte Carlo simulations and measured the distance (nearest neighbors) between acoustic and LMA sources. For close sources (<5 km) the mean nearest-neighbors distance was 185 m compared to 100 m predicted by the Monte Carlo analysis. For far distances (>6 km) the error increases to 800 m for the nearest neighbors and 650 m for the Monte Carlo analysis. This work shows that thunder sources can be accurately located using acoustic signals.

Acoustic multipath arrivals in the horizontal plane due to approaching nonlinear internal waves.

PubMed

Badiey, Mohsen; Katsnelson, Boris G; Lin, Ying-Tsong; Lynch, James F

2011-04-01

Simultaneous measurements of acoustic wave transmissions and a nonlinear internal wave packet approaching an along-shelf acoustic path during the Shallow Water 2006 experiment are reported. The incoming internal wave packet acts as a moving frontal layer reflecting (or refracting) sound in the horizontal plane. Received acoustic signals are filtered into acoustic normal mode arrivals. It is shown that a horizontal multipath interference is produced. This has previously been called a horizontal Lloyd's mirror. The interference between the direct path and the refracted path depends on the mode number and frequency of the acoustic signal. A mechanism for the multipath interference is shown. Preliminary modeling results of this dynamic interaction using vertical modes and horizontal parabolic equation models are in good agreement with the observed data.

Fatigue crack localization with near-field acoustic emission signals

NASA Astrophysics Data System (ADS)

Zhou, Changjiang; Zhang, Yunfeng

2013-04-01

This paper presents an AE source localization technique using near-field acoustic emission (AE) signals induced by crack growth and propagation. The proposed AE source localization technique is based on the phase difference in the AE signals measured by two identical AE sensing elements spaced apart at a pre-specified distance. This phase difference results in canceling-out of certain frequency contents of signals, which can be related to AE source direction. Experimental data from simulated AE source such as pencil breaks was used along with analytical results from moment tensor analysis. It is observed that the theoretical predictions, numerical simulations and the experimental test results are in good agreement. Real data from field monitoring of an existing fatigue crack on a bridge was also used to test this system. Results show that the proposed method is fairly effective in determining the AE source direction in thick plates commonly encountered in civil engineering structures.

Elevated stress hormone diminishes the strength of female preferences for acoustic signals in the green treefrog.

PubMed

Davis, A Gabriell; Leary, Christopher J

2015-03-01

Mate selection can be stressful; time spent searching for mates can increase predation risk and/or decrease food consumption, resulting in elevated stress hormone levels. Both high predation risk and low food availability are often associated with increased variation in mate choice by females, but it is not clear whether stress hormone levels contribute to such variation in female behavior. We examined how the stress hormone corticosterone (CORT) affects female preferences for acoustic signals in the green treefrog, Hyla cinerea. Specifically, we assessed whether CORT administration affects female preferences for call rate - an acoustic feature that is typically under directional selection via mate choice by females in most anurans and other species that communicate using acoustic signals. Using a dual speaker playback paradigm, we show that females that were administered higher doses of CORT were less likely to choose male advertisement calls broadcast at high rates. Neither CORT dose nor level was related to the latency of female phonotactic responses, suggesting that elevated CORT does not influence the motivation to mate. Results were also not related to circulating sex steroids (i.e., progesterone, androgens or estradiol) that have traditionally been the focus of studies examining the hormonal basis for variation in female mate choice. Our results thus indicate that elevated CORT levels decrease the strength of female preferences for acoustic signals. Copyright © 2015 Elsevier Inc. All rights reserved.

Temporal and acoustic characteristics of Greek vowels produced by adults with cerebral palsy

NASA Astrophysics Data System (ADS)

Botinis, Antonis; Orfanidou, Ioanna; Fourakis, Marios; Fourakis, Marios

2005-09-01

The present investigation examined the temporal and spectral characteristics of Greek vowels as produced by speakers with intact (NO) versus cerebral palsy affected (CP) neuromuscular systems. Six NO and six CP native speakers of Greek produced the Greek vowels [i, e, a, o, u] in the first syllable of CVCV nonsense words in a short carrier phrase. Stress could be on either the first or second syllable. There were three female and three male speakers in each group. In terms of temporal characteristics, the results showed that: vowels produced by CP speakers were longer than vowels produced by NO speakers; stressed vowels were longer than unstressed vowels; vowels produced by female speakers were longer than vowels produced by male speakers. In terms of spectral characteristics the results showed that the vowel space of the CP speakers was smaller than that of the NO speakers. This is similar to the results recently reported by Liu et al. [J. Acoust. Soc. Am. 117, 3879-3889 (2005)] for CP speakers of Mandarin. There was also a reduction of the acoustic vowel space defined by unstressed vowels, but this reduction was much more pronounced in the vowel productions of CP speakers than NO speakers.

Studies on Automobile Clutch Release Bearing Characteristics with Acoustic Emission

NASA Astrophysics Data System (ADS)

Chen, Guoliang; Chen, Xiaoyang

Automobile clutch release bearings are important automotive driveline components. For the clutch release bearing, early fatigue failure diagnosis is significant, but the early fatigue failure response signal is not obvious, because failure signals are susceptible to noise on the transmission path and to working environment factors such as interference. With an improvement in vehicle design, clutch release bearing fatigue life indicators have increasingly become an important requirement. Contact fatigue is the main failure mode of release rolling bearing components. Acoustic emission techniques in contact fatigue failure detection have unique advantages, which include highly sensitive nondestructive testing methods. In the acoustic emission technique to detect a bearing, signals are collected from multiple sensors. Each signal contains partial fault information, and there is overlap between the signals' fault information. Therefore, the sensor signals receive simultaneous source information integration is complete fragment rolling bearing fault acoustic emission signal, which is the key issue of accurate fault diagnosis. Release bearing comprises the following components: the outer ring, inner ring, rolling ball, cage. When a failure occurs (such as cracking, pitting), the other components will impact damaged point to produce acoustic emission signal. Release bearings mainly emit an acoustic emission waveform with a Rayleigh wave propagation. Elastic waves emitted from the sound source, and it is through the part surface bearing scattering. Dynamic simulation of rolling bearing failure will contribute to a more in-depth understanding of the characteristics of rolling bearing failure, because monitoring and fault diagnosis of rolling bearings provide a theoretical basis and foundation.

Real-time implementations of acoustic signal enhancement techniques for aerial based surveillance and rescue applications

NASA Astrophysics Data System (ADS)

Ramos, Antonio L. L.; Shao, Zhili; Holthe, Aleksander; Sandli, Mathias F.

2017-05-01

The introduction of the System-on-Chip (SoC) technology has brought exciting new opportunities for the development of smart low cost embedded systems spanning a wide range of applications. Currently available SoC devices are capable of performing high speed digital signal processing tasks in software while featuring relatively low development costs and reduced time-to-market. Unmanned aerial vehicles (UAV) are an application example that has shown tremendous potential in an increasing number of scenarios, ranging from leisure to surveillance as well as in search and rescue missions. Video capturing from UAV platforms is a relatively straightforward task that requires almost no preprocessing. However, that does not apply to audio signals, especially in cases where the data is to be used to support real-time decision making. In fact, the enormous amount of acoustic interference from the surroundings, including the noise from the UAVs propellers, becomes a huge problem. This paper discusses a real-time implementation of the NLMS adaptive filtering algorithm applied to enhancing acoustic signals captured from UAV platforms. The model relies on a combination of acoustic sensors and a computational inexpensive algorithm running on a digital signal processor. Given its simplicity, this solution can be incorporated into the main processing system of an UAV using the SoC technology, and run concurrently with other required tasks, such as flight control and communications. Simulations and real-time DSP-based implementations have shown significant signal enhancement results by efficiently mitigating the interference from the noise generated by the UAVs propellers as well as from other external noise sources.

Acoustic vibrations contribute to the diffuse scatter produced by ribosome crystals

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

Polikanov, Yury S.; Moore, Peter B.

2015-09-26

The diffuse scattering pattern produced by frozen crystals of the 70S ribosome fromThermus thermophilusis as highly structured as it would be if it resulted entirely from domain-scale motions within these particles. However, the qualitative properties of the scattering pattern suggest that acoustic displacements of the crystal lattice make a major contribution to it.

Acoustic velocity measurements in materials using a regenerative method

DOEpatents

Laine, Edwin F.

1986-01-01

Acoustic energy is propagated through earth material between an electro-acoustic generator and a receiver which converts the received acoustic energy into electrical signals. A closed loop is formed by a variable gain amplifier system connected between the receiver and the generator. The gain of the amplifier system is increased until sustained oscillations are produced in the closed loop. The frequency of the oscillations is measured as an indication of the acoustic propagation velocity through the earth material. The amplifier gain is measured as an indication of the acoustic attenuation through the earth materials. The method is also applicable to the non-destructive testing of structural materials, such as steel, aluminum and concrete.

Acoustic-velocity measurements in materials using a regenerative method

DOEpatents

Laine, E.F.

1982-09-30

Acoustic energy is propatated through earth material between an electro-acoustic generator and a receiver which converts the received acoustic energy into electrical signals. A closed loop is formed by a variable gain amplifier system connected between the receiver and the generator. The gain of the amplifier system is increased until sustained oscillations are produced in the closed loop. The frequency of the oscillations is measured as an indication of the acoustic propagation velocity through the earth material. The amplifier gain is measured as an indication of the acoustic attenuation through the earth materials. The method is also applicable to the non-destructive testing of structural materials, such as steel, aluminum and concrete.

Acoustic analysis of trill sounds.

PubMed

Dhananjaya, N; Yegnanarayana, B; Bhaskararao, Peri

2012-04-01

In this paper, the acoustic-phonetic characteristics of steady apical trills--trill sounds produced by the periodic vibration of the apex of the tongue--are studied. Signal processing methods, namely, zero-frequency filtering and zero-time liftering of speech signals, are used to analyze the excitation source and the resonance characteristics of the vocal tract system, respectively. Although it is natural to expect the effect of trilling on the resonances of the vocal tract system, it is interesting to note that trilling influences the glottal source of excitation as well. The excitation characteristics derived using zero-frequency filtering of speech signals are glottal epochs, strength of impulses at the glottal epochs, and instantaneous fundamental frequency of the glottal vibration. Analysis based on zero-time liftering of speech signals is used to study the dynamic resonance characteristics of vocal tract system during the production of trill sounds. Qualitative analysis of trill sounds in different vowel contexts, and the acoustic cues that may help spotting trills in continuous speech are discussed.

Department of Cybernetic Acoustics

NASA Astrophysics Data System (ADS)

The development of the theory, instrumentation and applications of methods and systems for the measurement, analysis, processing and synthesis of acoustic signals within the audio frequency range, particularly of the speech signal and the vibro-acoustic signal emitted by technical and industrial equipments treated as noise and vibration sources was discussed. The research work, both theoretical and experimental, aims at applications in various branches of science, and medicine, such as: acoustical diagnostics and phoniatric rehabilitation of pathological and postoperative states of the speech organ; bilateral ""man-machine'' speech communication based on the analysis, recognition and synthesis of the speech signal; vibro-acoustical diagnostics and continuous monitoring of the state of machines, technical equipments and technological processes.

Studies of acoustic emission from point and extended sources

NASA Technical Reports Server (NTRS)

Sachse, W.; Kim, K. Y.; Chen, C. P.

1986-01-01

The use of simulated and controlled acoustic emission signals forms the basis of a powerful tool for the detailed study of various deformation and wave interaction processes in materials. The results of experiments and signal analyses of acoustic emission resulting from point sources such as various types of indentation-produced cracks in brittle materials and the growth of fatigue cracks in 7075-T6 aluminum panels are discussed. Recent work dealing with the modeling and subsequent signal processing of an extended source of emission in a material is reviewed. Results of the forward problem and the inverse problem are presented with the example of a source distributed through the interior of a specimen.

Effects of optical attenuation, heat diffusion, and acoustic coherence in photoacoustic signals produced by nanoparticles

NASA Astrophysics Data System (ADS)

Alba-Rosales, J. E.; Ramos-Ortiz, G.; Escamilla-Herrera, L. F.; Reyes-Ramírez, B.; Polo-Parada, L.; Gutiérrez-Juárez, G.

2018-04-01

The behavior of the photoacoustic signal produced by nanoparticles as a function of their concentration was studied in detail. As the concentration of nanoparticles is increased in a sample, the peak-to-peak photoacoustic amplitude increases linearly up to a certain value, after which an asymptotic saturated behavior is observed. To elucidate the mechanisms responsible for these observations, we evaluate the effects of nanoparticles concentration, the optical attenuation, and the effects of heat propagation from nano-sources to their surroundings. We found that the saturation effect of the photoacoustic signal as a function of the concentration of nanoparticles is explained by a combination of two different mechanisms. As has been suggested previously, but not modeled correctly, the most important mechanism is attributed to optical attenuation. The second mechanism is due to an interference destructive process attributed to the superimposition of the photoacoustic amplitudes generated for each nanoparticle, and this explanation is reinforced through our experimental and simulations results; based on this, it is found that the linear behavior of the photoacoustic amplitude could be restricted to optical densities ≤0.5.

Singing whales generate high levels of particle motion: implications for acoustic communication and hearing?

PubMed

Mooney, T Aran; Kaplan, Maxwell B; Lammers, Marc O

2016-11-01

Acoustic signals are fundamental to animal communication, and cetaceans are often considered bioacoustic specialists. Nearly all studies of their acoustic communication focus on sound pressure measurements, overlooking the particle motion components of their communication signals. Here we characterized the levels of acoustic particle velocity (and pressure) of song produced by humpback whales. We demonstrate that whales generate acoustic fields that include significant particle velocity components that are detectable over relatively long distances sufficient to play a role in acoustic communication. We show that these signals attenuate predictably in a manner similar to pressure and that direct particle velocity measurements can provide bearings to singing whales. Whales could potentially use such information to determine the distance of signalling animals. Additionally, the vibratory nature of particle velocity may stimulate bone conduction, a hearing modality found in other low-frequency specialized mammals, offering a parsimonious mechanism of acoustic energy transduction into the massive ossicles of whale ears. With substantial concerns regarding the effects of increasing anthropogenic ocean noise and major uncertainties surrounding mysticete hearing, these results highlight both an unexplored pathway that may be available for whale acoustic communication and the need to better understand the biological role of acoustic particle motion. © 2016 The Author(s).

Singing whales generate high levels of particle motion: implications for acoustic communication and hearing?

PubMed Central

Kaplan, Maxwell B.; Lammers, Marc O.

2016-01-01

Acoustic signals are fundamental to animal communication, and cetaceans are often considered bioacoustic specialists. Nearly all studies of their acoustic communication focus on sound pressure measurements, overlooking the particle motion components of their communication signals. Here we characterized the levels of acoustic particle velocity (and pressure) of song produced by humpback whales. We demonstrate that whales generate acoustic fields that include significant particle velocity components that are detectable over relatively long distances sufficient to play a role in acoustic communication. We show that these signals attenuate predictably in a manner similar to pressure and that direct particle velocity measurements can provide bearings to singing whales. Whales could potentially use such information to determine the distance of signalling animals. Additionally, the vibratory nature of particle velocity may stimulate bone conduction, a hearing modality found in other low-frequency specialized mammals, offering a parsimonious mechanism of acoustic energy transduction into the massive ossicles of whale ears. With substantial concerns regarding the effects of increasing anthropogenic ocean noise and major uncertainties surrounding mysticete hearing, these results highlight both an unexplored pathway that may be available for whale acoustic communication and the need to better understand the biological role of acoustic particle motion. PMID:27807249

49 CFR 392.24 - Emergency signals; flame-producing.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 5 2011-10-01 2011-10-01 false Emergency signals; flame-producing. 392.24 Section... COMMERCIAL MOTOR VEHICLES Stopped Commercial Motor Vehicles § 392.24 Emergency signals; flame-producing. No... signal to any part of a commercial motor vehicle. [33 FR 19732, Dec. 25, 1968, as amended at 60 FR 38747...

49 CFR 392.24 - Emergency signals; flame-producing.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 5 2010-10-01 2010-10-01 false Emergency signals; flame-producing. 392.24 Section... COMMERCIAL MOTOR VEHICLES Stopped Commercial Motor Vehicles § 392.24 Emergency signals; flame-producing. No... signal to any part of a commercial motor vehicle. [33 FR 19732, Dec. 25, 1968, as amended at 60 FR 38747...

49 CFR 392.24 - Emergency signals; flame-producing.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 5 2014-10-01 2014-10-01 false Emergency signals; flame-producing. 392.24 Section... COMMERCIAL MOTOR VEHICLES Stopped Commercial Motor Vehicles § 392.24 Emergency signals; flame-producing. No... signal to any part of a commercial motor vehicle. [33 FR 19732, Dec. 25, 1968, as amended at 60 FR 38747...

49 CFR 392.24 - Emergency signals; flame-producing.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 5 2013-10-01 2013-10-01 false Emergency signals; flame-producing. 392.24 Section... COMMERCIAL MOTOR VEHICLES Stopped Commercial Motor Vehicles § 392.24 Emergency signals; flame-producing. No... signal to any part of a commercial motor vehicle. [33 FR 19732, Dec. 25, 1968, as amended at 60 FR 38747...

49 CFR 392.24 - Emergency signals; flame-producing.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 5 2012-10-01 2012-10-01 false Emergency signals; flame-producing. 392.24 Section... COMMERCIAL MOTOR VEHICLES Stopped Commercial Motor Vehicles § 392.24 Emergency signals; flame-producing. No... signal to any part of a commercial motor vehicle. [33 FR 19732, Dec. 25, 1968, as amended at 60 FR 38747...

Acoustic emission from single point machining: Part 2, Signal changes with tool wear

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

Heiple, C.R.; Carpenter, S.H.; Armentrout, D.L.

1989-01-01

Changes in acoustic emission signal characteristics with tool wear were monitored during single point machining of 4340 steel and Ti-6Al-4V heat treated to several strength levels, 606l-T6 aluminum, 304 stainless steel, 17-4PH stainless steel, 410 stainless steel, lead, and teflon. No signal characteristic changed in the same way with tool wear for all materials tested. A single change in a particular AE signal characteristic with tool wear valid for all materials probably does not exist. Nevertheless, changes in various signal characteristic with wear for a given material may be sufficient to be used to monitor tool wear.

Exploring results of the possibility on detecting cosmic ray particles by acoustic way

NASA Technical Reports Server (NTRS)

Jiang, Y.; Yuan, Y.; Li, Y.; Chen, D.; Zheng, R.; Song, J.

1985-01-01

It has been demonstrated experimentally and theoretically that high energy particles produce detectable sounds in water. However, no one has been able to detect an acoustic signal generated by a high energy cosmic ray particle in water. Results show that transient ultrasonic signals in a large lake or reservoir are fairly complex and that the transient signals under water may arise mainly from sound radiation from microbubbles. This field is not explored in detail. Perhaps, the sounds created by cosmic ray particles hide in these ultrasonic signals. In order to develop the technique of acoustic detection, it is most important to make a thorough investigation of these ultrasonic signals in water.

Fatigue Level Estimation of Bill Based on Acoustic Signal Feature by Supervised SOM

NASA Astrophysics Data System (ADS)

Teranishi, Masaru; Omatu, Sigeru; Kosaka, Toshihisa

Fatigued bills have harmful influence on daily operation of Automated Teller Machine(ATM). To make the fatigued bills classification more efficient, development of an automatic fatigued bill classification method is desired. We propose a new method to estimate bending rigidity of bill from acoustic signal feature of banking machines. The estimated bending rigidities are used as continuous fatigue level for classification of fatigued bill. By using the supervised Self-Organizing Map(supervised SOM), we estimate the bending rigidity from only the acoustic energy pattern effectively. The experimental result with real bill samples shows the effectiveness of the proposed method.

Seismo-acoustic Signals Recorded at KSIAR, the Infrasound Array Installed at PS31

NASA Astrophysics Data System (ADS)

Kim, T. S.; Che, I. Y.; Jeon, J. S.; Chi, H. C.; Kang, I. B.

2014-12-01

One of International Monitoring System (IMS)'s primary seismic stations, PS31, called Korea Seismic Research Station (KSRS), was installed around Wonju, Korea in 1970s. It has been operated by US Air Force Technical Applications Center (AFTAC) for more than 40 years. KSRS is composed of 26 seismic sensors including 19 short period, 6 long period and 1 broad band seismometers. The 19 short period sensors were used to build an array with a 10-km aperture while the 6 long period sensors were used for a relatively long period array with a 40-km aperture. After KSRS was certified as an IMS station in 2006 by Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), Korea Institute of Geoscience and Mineral Resources (KIGAM) which is the Korea National Data Center started to take over responsibilities on the operation and maintenance of KSRS from AFTAC. In April of 2014, KIGAM installed an infrasound array, KSIAR, on the existing four short period seismic stations of KSRS, the sites KS05, KS06, KS07 and KS16. The collocated KSIAR changed KSRS from a seismic array into a seismo-acoustic array. The aperture of KSIAR is 3.3 km. KSIAR also has a 100-m small aperture infrasound array at KS07. The infrasound data from KSIAR except that from the site KS06 is being transmitted in real time to KIGAM with VPN and internet line. An initial analysis on seismo-acoustic signals originated from local and regional distance ranges has been performed since May 2014. The analysis with the utilization of an array process called Progressive Multi-Channel Correlation (PMCC) detected seismo-acoustic signals caused by various sources including small explosions in relation to constructing local tunnels and roads. Some of them were not found in the list of automatic bulletin of KIGAM. The seismo-acoustic signals recorded by KSIAR are supplying a useful information for discriminating local and regional man-made events from natural events.

Overview of hydro-acoustic current-measurement applications by the U.S. geological survey in Indiana

USGS Publications Warehouse

Morlock, Scott E.; Stewart, James A.

1999-01-01

The U.S. Geological Survey (USGS) maintains a network of 170 streamflow-gaging stations in Indiana to collect data from which continuous records of river discharges are produced. Traditionally, the discharge record from a station is produced by recording river stage and making periodic discharge measurements through a range of stage, then developing a relation between stage and discharge. Techniques that promise to increase data collection accuracy and efficiency include the use of hydro-acoustic instrumentation to measure river velocities. The velocity measurements are used to compute river discharge. In-situ applications of hydro-acoustic instruments by the USGS in Indiana include acoustic velocity meters (AVM's) at six streamflow-gaging stations and newly developed Doppler velocity meters (DVM's) at two stations. AVM's use reciprocal travel times of acoustic signals to measure average water velocities along acoustic paths, whereas DVM's use the Doppler shift of backscattered acoustic signals to compute water velocities. In addition to the in-situ applications, three acoustic Doppler current profilers (ADCP's) are used to make river-discharge measurements from moving boats at streamflow-gaging stations in Indiana. The USGS has designed and is testing an innovative unmanned platform from which to make ADCP discharge measurements.

Flow velocity profiling using acoustic time of flight flow metering based on wide band signals and adaptive beam-forming techniques

NASA Astrophysics Data System (ADS)

Murgan, I.; Candel, I.; Ioana, C.; Digulescu, A.; Bunea, F.; Ciocan, G. D.; Anghel, A.; Vasile, G.

2016-11-01

In this paper, we present a novel approach to non-intrusive flow velocity profiling technique using multi-element sensor array and wide-band signal's processing methods. Conventional techniques for the measurements of the flow velocity profiles are usually based on intrusive instruments (current meters, acoustic Doppler profilers, Pitot tubes, etc.) that take punctual velocity readings. Although very efficient, these choices are limited in terms of practical cases of applications especially when non-intrusive measurements techniques are required and/or a spatial accuracy of the velocity profiling is required This is due to factors related to hydraulic machinery down time, the often long time duration needed to explore the entire section area, the frequent cumbersome number of devices that needs to be handled simultaneously, or the impossibility to perform intrusive tests. In the case of non-intrusive flow profiling methods based on acoustic techniques, previous methods concentrated on using a large number of acoustic transducers placed around the measured section. Although feasible, this approach presents several major drawbacks such as a complicated signal timing, transmission, acquisition and recording system, resulting in a relative high cost of operation. In addition, because of the geometrical constraints, a desired number of sensors may not be installed. Recent results in acoustic flow metering based on wide band signals and adaptive beamforming proved that it is possible to achieve flow velocity profiles using less acoustic transducers. In a normal acoustic time of flight path the transducers are both emitters and receivers, sequentially changing their roles. In the new configuration, proposed in this paper, two new receivers are added on each side. Since the beam angles of each acoustic transducer are wide enough the newly added transducers can receive the transmitted signals and additional time of flight estimation can be done. Thus, several flow

An acoustic switch.

PubMed

Vanhille, Christian; Campos-Pozuelo, Cleofé

2014-01-01

The benefits derived from the development of acoustic transistors which act as switches or amplifiers have been reported in the literature. Here we propose a model of acoustic switch. We theoretically demonstrate that the device works: the input signal is totally restored at the output when the switch is on whereas the output signal nulls when the switch is off. The switch, on or off, depends on a secondary acoustic field capable to manipulate the main acoustic field. The model relies on the attenuation effect of many oscillating bubbles on the main travelling wave in the liquid, as well as on the capacity of the secondary acoustic wave to move the bubbles. This model evidences the concept of acoustic switch (transistor) with 100% efficiency. Copyright © 2013 Elsevier B.V. All rights reserved.

An acoustical study of English word stress produced by Americans and Koreans

NASA Astrophysics Data System (ADS)

Yang, Byunggon

2002-05-01

Acoustical correlates of stress can be divided into duration, intensity, and fundamental frequency. This study examined the acoustical difference in the first two syllables of stressed English words produced by ten American and Korean speakers. The Korean subjects scored very high in TOEFL. They read, at a normal speed, a fable from which the acoustical parameters of eight words were analyzed. In order to make the data comparison meaningful, each parameter was collected at 100 dynamic time points proportional to the total duration of the two syllables. Then, the ratio of the parameter sum of the first rime to that of the second rime was calculated to determine the relative prominence of the syllables. Results showed that the durations of the first two syllables were almost comparable between the Americans and Koreans. However, statistically significant differences showed up in the diphthong pronunciations and in the words with the second syllable stressed. Also, remarkably high r-squared values were found between pairs of the three acoustical parameters, which suggests that either one or a combination of two or more parameters may account for the prominence of a syllable within a word. [Work supported by Korea Science Foundation R01-1999-00229.

Acoustic Imaging of Snowpack Physical Properties

NASA Astrophysics Data System (ADS)

Kinar, N. J.; Pomeroy, J. W.

2011-12-01

Measurements of snowpack depth, density, structure and temperature have often been conducted by the use of snowpits and invasive measurement devices. Previous research has shown that acoustic waves passing through snow are capable of measuring these properties. An experimental observation device (SAS2, System for the Acoustic Sounding of Snow) was used to autonomously send audible sound waves into the top of the snowpack and to receive and process the waves reflected from the interior and bottom of the snowpack. A loudspeaker and microphone array separated by an offset distance was suspended in the air above the surface of the snowpack. Sound waves produced from a loudspeaker as frequency-swept sequences and maximum length sequences were used as source signals. Up to 24 microphones measured the audible signal from the snowpack. The signal-to-noise ratio was compared between sequences in the presence of environmental noise contributed by wind and reflections from vegetation. Beamforming algorithms were used to reject spurious reflections and to compensate for movement of the sensor assembly during the time of data collection. A custom-designed circuit with digital signal processing hardware implemented an inversion algorithm to relate the reflected sound wave data to snowpack physical properties and to create a two-dimensional image of snowpack stratigraphy. The low power consumption circuit was powered by batteries and through WiFi and Bluetooth interfaces enabled the display of processed data on a mobile device. Acoustic observations were logged to an SD card after each measurement. The SAS2 system was deployed at remote field locations in the Rocky Mountains of Alberta, Canada. Acoustic snow properties data was compared with data collected from gravimetric sampling, thermocouple arrays, radiometers and snowpit observations of density, stratigraphy and crystal structure. Aspects for further research and limitations of the acoustic sensing system are also discussed.

Acoustic signal detection of manatee calls

NASA Astrophysics Data System (ADS)

Niezrecki, Christopher; Phillips, Richard; Meyer, Michael; Beusse, Diedrich O.

2003-04-01

The West Indian manatee (trichechus manatus latirostris) has become endangered partly because of a growing number of collisions with boats. A system to warn boaters of the presence of manatees, that can signal to boaters that manatees are present in the immediate vicinity, could potentially reduce these boat collisions. In order to identify the presence of manatees, acoustic methods are employed. Within this paper, three different detection algorithms are used to detect the calls of the West Indian manatee. The detection systems are tested in the laboratory using simulated manatee vocalizations from an audio compact disc. The detection method that provides the best overall performance is able to correctly identify ~=96% of the manatee vocalizations. However the system also results in a false positive rate of ~=16%. The results of this work may ultimately lead to the development of a manatee warning system that can warn boaters of the presence of manatees.

Acoustic Remote Sensing

NASA Astrophysics Data System (ADS)

Dowling, David R.; Sabra, Karim G.

2015-01-01

Acoustic waves carry information about their source and collect information about their environment as they propagate. This article reviews how these information-carrying and -collecting features of acoustic waves that travel through fluids can be exploited for remote sensing. In nearly all cases, modern acoustic remote sensing involves array-recorded sounds and array signal processing to recover multidimensional results. The application realm for acoustic remote sensing spans an impressive range of signal frequencies (10-2 to 107 Hz) and distances (10-2 to 107 m) and involves biomedical ultrasound imaging, nondestructive evaluation, oil and gas exploration, military systems, and Nuclear Test Ban Treaty monitoring. In the past two decades, approaches have been developed to robustly localize remote sources; remove noise and multipath distortion from recorded signals; and determine the acoustic characteristics of the environment through which the sound waves have traveled, even when the recorded sounds originate from uncooperative sources or are merely ambient noise.

Magneto-acoustic imaging by continuous-wave excitation.

PubMed

Shunqi, Zhang; Zhou, Xiaoqing; Tao, Yin; Zhipeng, Liu

2017-04-01

The electrical characteristics of tissue yield valuable information for early diagnosis of pathological changes. Magneto-acoustic imaging is a functional approach for imaging of electrical conductivity. This study proposes a continuous-wave magneto-acoustic imaging method. A kHz-range continuous signal with an amplitude range of several volts is used to excite the magneto-acoustic signal and improve the signal-to-noise ratio. The magneto-acoustic signal amplitude and phase are measured to locate the acoustic source via lock-in technology. An optimisation algorithm incorporating nonlinear equations is used to reconstruct the magneto-acoustic source distribution based on the measured amplitude and phase at various frequencies. Validation simulations and experiments were performed in pork samples. The experimental and simulation results agreed well. While the excitation current was reduced to 10 mA, the acoustic signal magnitude increased up to 10 -7  Pa. Experimental reconstruction of the pork tissue showed that the image resolution reached mm levels when the excitation signal was in the kHz range. The signal-to-noise ratio of the detected magneto-acoustic signal was improved by more than 25 dB at 5 kHz when compared to classical 1 MHz pulse excitation. The results reported here will aid further research into magneto-acoustic generation mechanisms and internal tissue conductivity imaging.

Differential phase acoustic microscope for micro-NDE

NASA Technical Reports Server (NTRS)

Waters, David D.; Pusateri, T. L.; Huang, S. R.

1992-01-01

A differential phase scanning acoustic microscope (DP-SAM) was developed, fabricated, and tested in this project. This includes the acoustic lens and transducers, driving and receiving electronics, scanning stage, scanning software, and display software. This DP-SAM can produce mechanically raster-scanned acoustic microscopic images of differential phase, differential amplitude, or amplitude of the time gated returned echoes of the samples. The differential phase and differential amplitude images provide better image contrast over the conventional amplitude images. A specially designed miniature dual beam lens was used to form two foci to obtain the differential phase and amplitude information of the echoes. High image resolution (1 micron) was achieved by applying high frequency (around 1 GHz) acoustic signals to the samples and placing two foci close to each other (1 micron). Tone burst was used in this system to obtain a good estimation of the phase differences between echoes from the two adjacent foci. The system can also be used to extract the V(z) acoustic signature. Since two acoustic beams and four receiving modes are available, there are 12 possible combinations to produce an image or a V(z) scan. This provides a unique feature of this system that none of the existing acoustic microscopic systems can provide for the micro-nondestructive evaluation applications. The entire system, including the lens, electronics, and scanning control software, has made a competitive industrial product for nondestructive material inspection and evaluation and has attracted interest from existing acoustic microscope manufacturers.

A comparative study of the SVM and K-nn machine learning algorithms for the diagnosis of respiratory pathologies using pulmonary acoustic signals.

PubMed

Palaniappan, Rajkumar; Sundaraj, Kenneth; Sundaraj, Sebastian

2014-06-27

Pulmonary acoustic parameters extracted from recorded respiratory sounds provide valuable information for the detection of respiratory pathologies. The automated analysis of pulmonary acoustic signals can serve as a differential diagnosis tool for medical professionals, a learning tool for medical students, and a self-management tool for patients. In this context, we intend to evaluate and compare the performance of the support vector machine (SVM) and K-nearest neighbour (K-nn) classifiers in diagnosis respiratory pathologies using respiratory sounds from R.A.L.E database. The pulmonary acoustic signals used in this study were obtained from the R.A.L.E lung sound database. The pulmonary acoustic signals were manually categorised into three different groups, namely normal, airway obstruction pathology, and parenchymal pathology. The mel-frequency cepstral coefficient (MFCC) features were extracted from the pre-processed pulmonary acoustic signals. The MFCC features were analysed by one-way ANOVA and then fed separately into the SVM and K-nn classifiers. The performances of the classifiers were analysed using the confusion matrix technique. The statistical analysis of the MFCC features using one-way ANOVA showed that the extracted MFCC features are significantly different (p < 0.001). The classification accuracies of the SVM and K-nn classifiers were found to be 92.19% and 98.26%, respectively. Although the data used to train and test the classifiers are limited, the classification accuracies found are satisfactory. The K-nn classifier was better than the SVM classifier for the discrimination of pulmonary acoustic signals from pathological and normal subjects obtained from the RALE database.

A comparative study of the svm and k-nn machine learning algorithms for the diagnosis of respiratory pathologies using pulmonary acoustic signals

PubMed Central

2014-01-01

Background Pulmonary acoustic parameters extracted from recorded respiratory sounds provide valuable information for the detection of respiratory pathologies. The automated analysis of pulmonary acoustic signals can serve as a differential diagnosis tool for medical professionals, a learning tool for medical students, and a self-management tool for patients. In this context, we intend to evaluate and compare the performance of the support vector machine (SVM) and K-nearest neighbour (K-nn) classifiers in diagnosis respiratory pathologies using respiratory sounds from R.A.L.E database. Results The pulmonary acoustic signals used in this study were obtained from the R.A.L.E lung sound database. The pulmonary acoustic signals were manually categorised into three different groups, namely normal, airway obstruction pathology, and parenchymal pathology. The mel-frequency cepstral coefficient (MFCC) features were extracted from the pre-processed pulmonary acoustic signals. The MFCC features were analysed by one-way ANOVA and then fed separately into the SVM and K-nn classifiers. The performances of the classifiers were analysed using the confusion matrix technique. The statistical analysis of the MFCC features using one-way ANOVA showed that the extracted MFCC features are significantly different (p < 0.001). The classification accuracies of the SVM and K-nn classifiers were found to be 92.19% and 98.26%, respectively. Conclusion Although the data used to train and test the classifiers are limited, the classification accuracies found are satisfactory. The K-nn classifier was better than the SVM classifier for the discrimination of pulmonary acoustic signals from pathological and normal subjects obtained from the RALE database. PMID:24970564

Acoustic emission frequency discrimination

NASA Technical Reports Server (NTRS)

Sugg, Frank E. (Inventor); Graham, Lloyd J. (Inventor)

1988-01-01

In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

TU-FG-BRB-08: Challenges, Limitations and Future Outlook Towards Clinical Translation of Proton Acoustic Range Verification

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

Yousefi, S; Ahmad, M; Xiang, L

Purpose: To report our investigations of proton acoustic imaging, including computer simulations and preliminary experimental studies at clinical facilities. The ultimate achievable accuracy, sensitivity and clinical translation challenges are discussed. Methods: The acoustic pulse due to pressure rise was estimated using finite element model. Since the ionoacoustic pulse is highly dependent on the proton pulse width and energy, multiple pulse widths were studied. Based on the received signal spectrum at piezoelectric ultrasound transducer with consideration of random thermal noise, maximum spatial resolution of the proton-acoustic imaging modality was calculated. The simulation studies defined the design specifications of the system tomore » detect proton acoustic signal from Hitachi and Mevion clinical machines. A 500 KHz hydrophone with 100 dB amplification was set up in a water tank placed in front of the proton nozzle A 40 MHz data acquisition was synchronized by a trigger signal provided by the machine. Results: Given 30–800 mGy dose per pulse at the Bragg peak, the minimum number of protons detectable by the proton acoustic technique was on the order of 10×10^6 per pulse. The broader pulse widths produce signal with lower acoustic frequencies, with 10 µs pulses producing signals with frequency less than 100 kHz. As the proton beam pulse width increases, a higher dose rate is required to measure the acoustic signal. Conclusion: We have established the minimal detection limit for protonacoustic range validation for a variety of pulse parameters. Our study indicated practical proton-acoustic range verification can be feasible with a pulse shorter than 10 µs, 5×10^6 protons/pulse, 50 nA beam current and a highly sensitive ultrasonic transducer. The translational challenges into current clinical machines include proper magnetic shielding of the measurement equipment, providing a clean trigger signal from the proton machine, providing a shorter proton beam

Wake acoustic analysis and image decomposition via beamforming of microphone signal projections on wavelet subspaces

DOT National Transportation Integrated Search

2006-05-08

This paper describes the integration of wavelet analysis and time-domain beamforming : of microphone array output signals for analyzing the acoustic emissions from airplane : generated wake vortices. This integrated process provides visual and quanti...

Amplitude Modulations of Acoustic Communication Signals

NASA Astrophysics Data System (ADS)

Turesson, Hjalmar K.

2011-12-01

In human speech, amplitude modulations at 3 -- 8 Hz are important for discrimination and detection. Two different neurophysiological theories have been proposed to explain this effect. The first theory proposes that, as a consequence of neocortical synaptic dynamics, signals that are amplitude modulated at 3 -- 8 Hz are propagated better than un-modulated signals, or signals modulated above 8 Hz. This suggests that neural activity elicited by vocalizations modulated at 3 -- 8 Hz is optimally transmitted, and the vocalizations better discriminated and detected. The second theory proposes that 3 -- 8 Hz amplitude modulations interact with spontaneous neocortical oscillations. Specifically, vocalizations modulated at 3 -- 8 Hz entrain local populations of neurons, which in turn, modulate the amplitude of high frequency gamma oscillations. This suggests that vocalizations modulated at 3 -- 8 Hz should induce stronger cross-frequency coupling. Similar to human speech, we found that macaque monkey vocalizations also are amplitude modulated between 3 and 8 Hz. Humans and macaque monkeys share similarities in vocal production, implying that the auditory systems subserving perception of acoustic communication signals also share similarities. Based on the similarities between human speech and macaque monkey vocalizations, we addressed how amplitude modulated vocalizations are processed in the auditory cortex of macaque monkeys, and what behavioral relevance modulations may have. Recording single neuron activity, as well as, the activity of local populations of neurons allowed us to test both of the neurophysiological theories presented above. We found that single neuron responses to vocalizations amplitude modulated at 3 -- 8 Hz resulted in better stimulus discrimination than vocalizations lacking 3 -- 8 Hz modulations, and that the effect most likely was mediated by synaptic dynamics. In contrast, we failed to find support for the oscillation-based model proposing a

Acoustic gravity microseismic pressure signal at shallow stations

NASA Astrophysics Data System (ADS)

Peureux, Charles; Ardhuin, Fabrice; Royer, Jean-Yves

2017-04-01

It has been known for decades that the background permanent seismic noise, the so-called microseimic signal, is generated by the nonlinear interaction of oppositely travelling ocean surface waves [Longuet-Higgins 1951]. It can especially be used to infer the time variability of short ocean waves statistics [Peureux and Ardhuin 2016]. However, better quantitative estimates of the latter are made difficult due to a poor knowledge of the Earth's crust characteristics, whose coupling with acoustic modes can affect large uncertainties to the frequency response at the bottom of the ocean. The pressure field at depths less than an acoustic wave length to the surface is made of evanescent acoustic-gravity modes [Cox and Jacobs 1989]. For this reason, they are less affected by the ocean bottom composition. This near field is recorded and analyzed in the frequency range 0.1 to 0.5 Hz approximately, at two locations : at a shallow site in the North-East Atlantic continental shelf and a deep water site in the Southern Indian ocean, at the ocean bottom and 100 m below sea-surface and in the upper part of the water column respectively. Evanescent and propagating Rayleigh modes are compared against theoretical predictions. Comparisons against surface waves hindcast based on WAVEWATCH(R) III modelling framework help assessing its performances and can be used to help future model improvements. References Longuet-Higgins, M. S., A Theory of the Origin of Microseisms, Philos. Trans. Royal Soc. A, The Royal Society, 1950, 243, 1-3. Peureux, C. and Ardhuin, F., Ocean bottom pressure records from the Cascadia array and short surface gravity waves, J. Geophys. Res. Oceans, 2016, 121, 2862-2873. Cox, C. S. & Jacobs, D. C., Cartesian diver observations of double frequency pressure fluctuations in the upper levels of the ocean, Geophys. Res. Lett., 1989, 16, 807-810.

Acoustic imaging system

DOEpatents

Smith, Richard W.

1979-01-01

An acoustic imaging system for displaying an object viewed by a moving array of transducers as the array is pivoted about a fixed point within a given plane. A plurality of transducers are fixedly positioned and equally spaced within a laterally extending array and operatively directed to transmit and receive acoustic signals along substantially parallel transmission paths. The transducers are sequentially activated along the array to transmit and receive acoustic signals according to a preestablished sequence. Means are provided for generating output voltages for each reception of an acoustic signal, corresponding to the coordinate position of the object viewed as the array is pivoted. Receptions from each of the transducers are presented on the same display at coordinates corresponding to the actual position of the object viewed to form a plane view of the object scanned.

Digital Signal Processing Methods for Ultrasonic Echoes.

PubMed

Sinding, Kyle; Drapaca, Corina; Tittmann, Bernhard

2016-04-28

Digital signal processing has become an important component of data analysis needed in industrial applications. In particular, for ultrasonic thickness measurements the signal to noise ratio plays a major role in the accurate calculation of the arrival time. For this application a band pass filter is not sufficient since the noise level cannot be significantly decreased such that a reliable thickness measurement can be performed. This paper demonstrates the abilities of two regularization methods - total variation and Tikhonov - to filter acoustic and ultrasonic signals. Both of these methods are compared to a frequency based filtering for digitally produced signals as well as signals produced by ultrasonic transducers. This paper demonstrates the ability of the total variation and Tikhonov filters to accurately recover signals from noisy acoustic signals faster than a band pass filter. Furthermore, the total variation filter has been shown to reduce the noise of a signal significantly for signals with clear ultrasonic echoes. Signal to noise ratios have been increased over 400% by using a simple parameter optimization. While frequency based filtering is efficient for specific applications, this paper shows that the reduction of noise in ultrasonic systems can be much more efficient with regularization methods.

Laser acoustic emission thermal technique (LAETT): a technique for generating acoustic emission in dental composites.

PubMed

Duray, S J; Lee, S Y; Menis, D L; Gilbert, J L; Lautenschlager, E P; Greener, E H

1996-01-01

This study was designed to investigate a new method for generating interfacial debonding between the resin matrix and filler particles of dental composites. A pilot study was conducted to evaluate laser-induced acoustic emission in dental resins filled with varying quantities of particles. Model systems of 50/50 BisGMA/TEGDMA resin reinforced with 0, 25, and 75 wt% 5-10 micrometers silanated BaSiO(6) were analyzed. The sample size was 3.5 mm diameter x 0.25-0.28 mm thick. A continuous wave CO2 laser (Synrad Infrared Gas Laser Model 48-1) was used to heat the composite samples. Acoustic events were detected, recorded and processed by a model 4610 Smart Acoustic Monitor (SAM) with a 1220A preamp (Physical Acoustic Corp.) as a function of laser power. Initially, the acoustic signal from the model composites produced a burst pattern characteristic of fracturing, about 3.7 watts laser power. Acoustic emission increased with laser power up to about 6 watts. At laser powers above 6 watts, the acoustic emission remained constant. The amount of acoustic emission followed the trend: unfilled resin > composite with 25 wt% BaSiO(6) > composite with 75 wt% BaSiO(6). Acoustic emission generated by laser thermal heating is dependent on the weight percent of filler particles in the composite and the amount of laser power. For this reason, laser thermal acoustic emission might be useful as a nondestructive form of analysis of dental composites.

Listening to the Deep: live monitoring of ocean noise and cetacean acoustic signals.

PubMed

André, M; van der Schaar, M; Zaugg, S; Houégnigan, L; Sánchez, A M; Castell, J V

2011-01-01

The development and broad use of passive acoustic monitoring techniques have the potential to help assessing the large-scale influence of artificial noise on marine organisms and ecosystems. Deep-sea observatories have the potential to play a key role in understanding these recent acoustic changes. LIDO (Listening to the Deep Ocean Environment) is an international project that is allowing the real-time long-term monitoring of marine ambient noise as well as marine mammal sounds at cabled and standalone observatories. Here, we present the overall development of the project and the use of passive acoustic monitoring (PAM) techniques to provide the scientific community with real-time data at large spatial and temporal scales. Special attention is given to the extraction and identification of high frequency cetacean echolocation signals given the relevance of detecting target species, e.g. beaked whales, in mitigation processes, e.g. during military exercises. Copyright © 2011. Published by Elsevier Ltd.

Acoustic emission from single point machining: Part 2, Signal changes with tool wear. Revised

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

Heiple, C.R.; Carpenter, S.H.; Armentrout, D.L.

1989-12-31

Changes in acoustic emission signal characteristics with tool wear were monitored during single point machining of 4340 steel and Ti-6Al-4V heat treated to several strength levels, 606l-T6 aluminum, 304 stainless steel, 17-4PH stainless steel, 410 stainless steel, lead, and teflon. No signal characteristic changed in the same way with tool wear for all materials tested. A single change in a particular AE signal characteristic with tool wear valid for all materials probably does not exist. Nevertheless, changes in various signal characteristic with wear for a given material may be sufficient to be used to monitor tool wear.

Transducer Design Experiments for Ground-Penetrating Acoustic Systems

DTIC Science & Technology

1996-03-19

subsurface imaging experiments have utilized a source (Tx) and receiver (Rx) configuration in which signals produced by a transmitter at the soil surface...development in the field of acoustic subsurface imaging are as follows. First, a transmitter designed to minimize the emission of surface waves, while

Extruded Bread Classification on the Basis of Acoustic Emission Signal With Application of Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Świetlicka, Izabela; Muszyński, Siemowit; Marzec, Agata

2015-04-01

The presented work covers the problem of developing a method of extruded bread classification with the application of artificial neural networks. Extruded flat graham, corn, and rye breads differening in water activity were used. The breads were subjected to the compression test with simultaneous registration of acoustic signal. The amplitude-time records were analyzed both in time and frequency domains. Acoustic emission signal parameters: single energy, counts, amplitude, and duration acoustic emission were determined for the breads in four water activities: initial (0.362 for rye, 0.377 for corn, and 0.371 for graham bread), 0.432, 0.529, and 0.648. For classification and the clustering process, radial basis function, and self-organizing maps (Kohonen network) were used. Artificial neural networks were examined with respect to their ability to classify or to cluster samples according to the bread type, water activity value, and both of them. The best examination results were achieved by the radial basis function network in classification according to water activity (88%), while the self-organizing maps network yielded 81% during bread type clustering.

Speaker compensation for local perturbation of fricative acoustic feedback.

PubMed

Casserly, Elizabeth D

2011-04-01

Feedback perturbation studies of speech acoustics have revealed a great deal about how speakers monitor and control their productions of segmental (e.g., formant frequencies) and non-segmental (e.g., pitch) linguistic elements. The majority of previous work, however, overlooks the role of acoustic feedback in consonant production and makes use of acoustic manipulations that effect either entire utterances or the entire acoustic signal, rather than more temporally and phonetically restricted alterations. This study, therefore, seeks to expand the feedback perturbation literature by examining perturbation of consonant acoustics that is applied in a time-restricted and phonetically specific manner. The spectral center of the alveopalatal fricative [∫] produced in vowel-fricative-vowel nonwords was incrementally raised until it reached the potential for [s]-like frequencies, but the characteristics of high-frequency energy outside the target fricative remained unaltered. An "offline," more widely accessible signal processing method was developed to perform this manipulation. The local feedback perturbation resulted in changes to speakers' fricative production that were more variable, idiosyncratic, and restricted than the compensation seen in more global acoustic manipulations reported in the literature. Implications and interpretations of the results, as well as future directions for research based on the findings, are discussed.

Introduction to acoustic emission

NASA Technical Reports Server (NTRS)

Possa, G.

1983-01-01

Typical acoustic emission signal characteristics are described and techniques which localize the signal source by processing the acoustic delay data from multiple sensors are discussed. The instrumentation, which includes sensors, amplifiers, pulse counters, a minicomputer and output devices is examined. Applications are reviewed.

A self-mixing based ring-type fiber-optic acoustic sensor

NASA Astrophysics Data System (ADS)

Wang, Lutang; Wu, Chunxu; Fang, Nian

2014-07-01

A novel, simple fiber-optic acoustic sensor consisting of a self-mixing effect based laser source and a ring-type interferometer is presented. With weak external optical feedbacks, the acoustic wave signals can be detected by measuring the changes of oscillating frequency of the laser diode, induced by the disturbances of sensing fiber, with the ring-type interferometer. The operation principles of the sensor system are explored in-depth and the experimental researches are carried out. The acoustic wave signals produced by various actions, such as by pencil broken, mental pin free falling and PZT are detected for evaluating the sensing performances of the experimental system. The investigation items include the sensitivity as well as frequency responses of the sensor system. An experiment for the detection of corona discharges is carried out, which occur in a high-voltage environment between two parallel copper electrodes, under different humidity levels. The satisfied experimental results are obtained. These experimental results well prove that our proposed sensing system has very high sensitivity and excellent high frequency responses characteristics in the detections of weak, high-frequency acoustic wave signals.

Comments on the origin of acoustic emission in fatigue testing of aluminum alloys

NASA Astrophysics Data System (ADS)

Heiple, C. R.; Carpenter, S. H.; Armentrout, D. L.

The size of acoustic emission (AE) signals expected from inclusion fracture during fatigue testing of 7075 aluminum has been estimated on the basis of previous measurements of AE produced by the fracture of boron particles incorporated into 2219 aluminum. The AF signal size expected from deformation in the plastic zone ahead of the fatigue crack was estimated from the results of tensile tests on 7075 aluminum. The signals predicted from both processes are near or below the noise level in the fatigue experiments and are therefore far too small to account for the signals actually observed. Nearly simultaneous fracture of multiple inclusions could produce signals as large as those observed in fatigue tests of 7075 aluminum, however, fatigue tests of 7050 aluminum produced signals as large or larger than in 7075. Since 7050 has substantially fewer inclusions than 7075, the simultaneous failure of multiple inclusions is unlikely to be a major AE source in fatigue testing of either aluminum alloy. Thus, the most probable source of acoustic emission during fatigue testing of 7075 and 7050 aluminum is the crack advance itself. The measured crack advance per cycle is large enough to release sufficient elastic energy to account for the AE signals observed.

Pulse analysis of acoustic emission signals

NASA Technical Reports Server (NTRS)

Houghton, J. R.; Packman, P. F.

1977-01-01

A method for the signature analysis of pulses in the frequency domain and the time domain is presented. Fourier spectrum, Fourier transfer function, shock spectrum and shock spectrum ratio were examined in the frequency domain analysis and pulse shape deconvolution was developed for use in the time domain analysis. Comparisons of the relative performance of each analysis technique are made for the characterization of acoustic emission pulses recorded by a measuring system. To demonstrate the relative sensitivity of each of the methods to small changes in the pulse shape, signatures of computer modeled systems with analytical pulses are presented. Optimization techniques are developed and used to indicate the best design parameter values for deconvolution of the pulse shape. Several experiments are presented that test the pulse signature analysis methods on different acoustic emission sources. These include acoustic emission associated with (a) crack propagation, (b) ball dropping on a plate, (c) spark discharge, and (d) defective and good ball bearings. Deconvolution of the first few micro-seconds of the pulse train is shown to be the region in which the significant signatures of the acoustic emission event are to be found.

Pulse analysis of acoustic emission signals

NASA Technical Reports Server (NTRS)

Houghton, J. R.; Packman, P. F.

1977-01-01

A method for the signature analysis of pulses in the frequency domain and the time domain is presented. Fourier spectrum, Fourier transfer function, shock spectrum and shock spectrum ratio were examined in the frequency domain analysis, and pulse shape deconvolution was developed for use in the time domain analysis. Comparisons of the relative performance of each analysis technique are made for the characterization of acoustic emission pulses recorded by a measuring system. To demonstrate the relative sensitivity of each of the methods to small changes in the pulse shape, signatures of computer modeled systems with analytical pulses are presented. Optimization techniques are developed and used to indicate the best design parameters values for deconvolution of the pulse shape. Several experiments are presented that test the pulse signature analysis methods on different acoustic emission sources. These include acoustic emissions associated with: (1) crack propagation, (2) ball dropping on a plate, (3) spark discharge and (4) defective and good ball bearings. Deconvolution of the first few micro-seconds of the pulse train are shown to be the region in which the significant signatures of the acoustic emission event are to be found.

Quantified acoustic-optical speech signal incongruity identifies cortical sites of audiovisual speech processing

PubMed Central

Bernstein, Lynne E.; Lu, Zhong-Lin; Jiang, Jintao

2008-01-01

A fundamental question about human perception is how the speech perceiving brain combines auditory and visual phonetic stimulus information. We assumed that perceivers learn the normal relationship between acoustic and optical signals. We hypothesized that when the normal relationship is perturbed by mismatching the acoustic and optical signals, cortical areas responsible for audiovisual stimulus integration respond as a function of the magnitude of the mismatch. To test this hypothesis, in a previous study, we developed quantitative measures of acoustic-optical speech stimulus incongruity that correlate with perceptual measures. In the current study, we presented low incongruity (LI, matched), medium incongruity (MI, moderately mismatched), and high incongruity (HI, highly mismatched) audiovisual nonsense syllable stimuli during fMRI scanning. Perceptual responses differed as a function of the incongruity level, and BOLD measures were found to vary regionally and quantitatively with perceptual and quantitative incongruity levels. Each increase in level of incongruity resulted in an increase in overall levels of cortical activity and in additional activations. However, the only cortical region that demonstrated differential sensitivity to the three stimulus incongruity levels (HI > MI > LI) was a subarea of the left supramarginal gyrus (SMG). The left SMG might support a fine-grained analysis of the relationship between audiovisual phonetic input in comparison with stored knowledge, as hypothesized here. The methods here show that quantitative manipulation of stimulus incongruity is a new and powerful tool for disclosing the system that processes audiovisual speech stimuli. PMID:18495091

An acoustic glottal source for vocal tract physical models

NASA Astrophysics Data System (ADS)

Hannukainen, Antti; Kuortti, Juha; Malinen, Jarmo; Ojalammi, Antti

2017-11-01

A sound source is proposed for the acoustic measurement of physical models of the human vocal tract. The physical models are produced by fast prototyping, based on magnetic resonance imaging during prolonged vowel production. The sound source, accompanied by custom signal processing algorithms, is used for two kinds of measurements from physical models of the vocal tract: (i) amplitude frequency response and resonant frequency measurements, and (ii) signal reconstructions at the source output according to a target pressure waveform with measurements at the mouth position. The proposed source and the software are validated by computational acoustics experiments and measurements on a physical model of the vocal tract corresponding to the vowels [] of a male speaker.

Phylogenetic signal in the acoustic parameters of the advertisement calls of four clades of anurans.

PubMed

Gingras, Bruno; Mohandesan, Elmira; Boko, Drasko; Fitch, W Tecumseh

2013-07-01

Anuran vocalizations, especially their advertisement calls, are largely species-specific and can be used to identify taxonomic affiliations. Because anurans are not vocal learners, their vocalizations are generally assumed to have a strong genetic component. This suggests that the degree of similarity between advertisement calls may be related to large-scale phylogenetic relationships. To test this hypothesis, advertisement calls from 90 species belonging to four large clades (Bufo, Hylinae, Leptodactylus, and Rana) were analyzed. Phylogenetic distances were estimated based on the DNA sequences of the 12S mitochondrial ribosomal RNA gene, and, for a subset of 49 species, on the rhodopsin gene. Mean values for five acoustic parameters (coefficient of variation of root-mean-square amplitude, dominant frequency, spectral flux, spectral irregularity, and spectral flatness) were computed for each species. We then tested for phylogenetic signal on the body-size-corrected residuals of these five parameters, using three statistical tests (Moran's I, Mantel, and Blomberg's K) and three models of genetic distance (pairwise distances, Abouheif's proximities, and the variance-covariance matrix derived from the phylogenetic tree). A significant phylogenetic signal was detected for most acoustic parameters on the 12S dataset, across statistical tests and genetic distance models, both for the entire sample of 90 species and within clades in several cases. A further analysis on a subset of 49 species using genetic distances derived from rhodopsin and from 12S broadly confirmed the results obtained on the larger sample, indicating that the phylogenetic signals observed in these acoustic parameters can be detected using a variety of genetic distance models derived either from a variable mitochondrial sequence or from a conserved nuclear gene. We found a robust relationship, in a large number of species, between anuran phylogenetic relatedness and acoustic similarity in the

Low frequency acoustic microscope

DOEpatents

Khuri-Yakub, Butrus T.

1986-11-04

A scanning acoustic microscope is disclosed for the detection and location of near surface flaws, inclusions or voids in a solid sample material. A focused beam of acoustic energy is directed at the sample with its focal plane at the subsurface flaw, inclusion or void location. The sample is scanned with the beam. Detected acoustic energy specularly reflected and mode converted at the surface of the sample and acoustic energy reflected by subsurface flaws, inclusions or voids at the focal plane are used for generating an interference signal which is processed and forms a signal indicative of the subsurface flaws, inclusions or voids.

Acoustic Signal Characteristics Measured with the LAMBDA III During CHURCH STROKE III

DTIC Science & Technology

1980-09-15

analysis. Dr. William M. Carey and Dr. Richard Doolittle participated in various stages of acquisition, processing and analysis of the information...reported herein. Drs. Carey , Doolittle and Mr. Gereben are the authors of this report. (U) This report: Acoustic Signal Characteristics Measured with... Tortugas Terrace and the East Yucatan Channel,the Catoche Tongue and the Eastern region of the Gulf of Mexico. (U) The exercise was conducted by the Long

Acoustic Levitator Power Device: Study of Ethylene-Glycol Water Mixtures

NASA Astrophysics Data System (ADS)

Caccamo, M. T.; Cannuli, A.; Calabrò, E.; Magazù, S.

2017-05-01

Acoustic levitator power device is formed by two vertically and opposed high output acoustic transducers working at 22 kHz frequency and produces sound pressure levels of 160 dB. The acoustic waves are monitored from an oscilloscope using a signal amplifier. The ability to perform contactless measurements, avoidance of undesired contamination from the container, are some of advantages of this apparatus. Acoustic levitation can be also used for sample preparation of high concentrated mixtures starting from solutions. In the present paper, an acoustic levitator power device is employed to collect data on levitated water mixtures of Ethylene Glycol (EG) which are then analysed by Infra-Red spectroscopy. The study allows to follow the drying process versus time and to obtain a gel-like compound characterized by an extended chemical crosslinking.

Probe beam deflection technique as acoustic emission directionality sensor with photoacoustic emission source.

PubMed

Barnes, Ronald A; Maswadi, Saher; Glickman, Randolph; Shadaram, Mehdi

2014-01-20

The goal of this paper is to demonstrate the unique capability of measuring the vector or angular information of propagating acoustic waves using an optical sensor. Acoustic waves were generated using photoacoustic interaction and detected by the probe beam deflection technique. Experiments and simulations were performed to study the interaction of acoustic emissions with an optical sensor in a coupling medium. The simulated results predict the probe beam and wavefront interaction and produced simulated signals that are verified by experiment.

Demodulation of acoustic telemetry binary phase shift keying signal based on high-order Duffing system

NASA Astrophysics Data System (ADS)

Yan, Bing-Nan; Liu, Chong-Xin; Ni, Jun-Kang; Zhao, Liang

2016-10-01

In order to grasp the downhole situation immediately, logging while drilling (LWD) technology is adopted. One of the LWD technologies, called acoustic telemetry, can be successfully applied to modern drilling. It is critical for acoustic telemetry technology that the signal is successfully transmitted to the ground. In this paper, binary phase shift keying (BPSK) is used to modulate carrier waves for the transmission and a new BPSK demodulation scheme based on Duffing chaos is investigated. Firstly, a high-order system is given in order to enhance the signal detection capability and it is realized through building a virtual circuit using an electronic workbench (EWB). Secondly, a new BPSK demodulation scheme is proposed based on the intermittent chaos phenomena of the new Duffing system. Finally, a system variable crossing zero-point equidistance method is proposed to obtain the phase difference between the system and the BPSK signal. Then it is determined that the digital signal transmitted from the bottom of the well is ‘0’ or ‘1’. The simulation results show that the demodulation method is feasible. Project supported by the National Natural Science Foundation of China (Grant No. 51177117) and the National Key Science & Technology Special Projects, China (Grant No. 2011ZX05021-005).

Enhancing acoustic signal response and absorption of an underwater coated plate by embedding periodical inhomogeneities.

PubMed

Zhang, Yanni; Pan, Jie

2017-12-01

An underwater structure is proposed for simultaneous detection and stealth purposes by embedding periodic signal conditioning plates (SCPs) at the interface of two elastic coatings attached to an elastic plate. Results show that the embedded SCPs can enhance sound absorption at frequencies below the coincidence frequency of the plate (f c ). Significantly enhanced absorption occurs at five peaks, of which the peak due to excited localized bending resonance in the outer coating between SCPs is the most significant. When the dilatational velocity of the outer coating equals that of the inner coating, nearly total absorption occurs in a wideband, owing to strong coupling between the localized waveguide resonance in the outer coating and that in the inner coating, and the diffraction waves by the SCPs. Meanwhile, an amplified acoustic signal of over 14 dB is observed at most frequencies within 0 ∼ f c at the coatings' interface close to the SCPs' edges, owing to focused stress formed there. Peaks in the signal response at maximal 30 dB are also observed. These peak frequencies are coincident with or close to the peak frequencies of absorption, demonstrating that significantly enhanced acoustic signal and absorption can be achieved simultaneously through the use of embedded periodic SCPs.

Discrimination of acoustic communication signals by grasshoppers (Chorthippus biguttulus): temporal resolution, temporal integration, and the impact of intrinsic noise.

PubMed

Ronacher, Bernhard; Wohlgemuth, Sandra; Vogel, Astrid; Krahe, Rüdiger

2008-08-01

A characteristic feature of hearing systems is their ability to resolve both fast and subtle amplitude modulations of acoustic signals. This applies also to grasshoppers, which for mate identification rely mainly on the characteristic temporal patterns of their communication signals. Usually the signals arriving at a receiver are contaminated by various kinds of noise. In addition to extrinsic noise, intrinsic noise caused by stochastic processes within the nervous system contributes to making signal recognition a difficult task. The authors asked to what degree intrinsic noise affects temporal resolution and, particularly, the discrimination of similar acoustic signals. This study aims at exploring the neuronal basis for sexual selection, which depends on exploiting subtle differences between basically similar signals. Applying a metric, by which the similarities of spike trains can be assessed, the authors investigated how well the communication signals of different individuals of the same species could be discriminated and correctly classified based on the responses of auditory neurons. This spike train metric yields clues to the optimal temporal resolution with which spike trains should be evaluated. (c) 2008 APA, all rights reserved

Multi-Phenomenology Explosion Monitoring (Multi-PEM). Signal Detection. Research to target smaller sources for tomorrow’s missions

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

Carmichael, Joshua Daniel

2015-12-12

This a guide on how to detect and identify explosions from various sources. For example, nuclear explosions produce acoustic, optical, and EMP outputs. Each signal can be buried in noise, but fusing detection statistics from seismic, acoustic, and electromagnetic signals results in clear detection otherwise unobtainable.

An acoustic analysis of laughter produced by congenitally deaf and normally hearing college students.

PubMed

Makagon, Maja M; Funayama, E Sumie; Owren, Michael J

2008-07-01

Relatively few empirical data are available concerning the role of auditory experience in nonverbal human vocal behavior, such as laughter production. This study compared the acoustic properties of laughter in 19 congenitally, bilaterally, and profoundly deaf college students and in 23 normally hearing control participants. Analyses focused on degree of voicing, mouth position, air-flow direction, temporal features, relative amplitude, fundamental frequency, and formant frequencies. Results showed that laughter produced by the deaf participants was fundamentally similar to that produced by the normally hearing individuals, which in turn was consistent with previously reported findings. Finding comparable acoustic properties in the sounds produced by deaf and hearing vocalizers confirms the presumption that laughter is importantly grounded in human biology, and that auditory experience with this vocalization is not necessary for it to emerge in species-typical form. Some differences were found between the laughter of deaf and hearing groups; the most important being that the deaf participants produced lower-amplitude and longer-duration laughs. These discrepancies are likely due to a combination of the physiological and social factors that routinely affect profoundly deaf individuals, including low overall rates of vocal fold use and pressure from the hearing world to suppress spontaneous vocalizations.

New acoustic techniques for leak detection in fossil fuel plant components

NASA Astrophysics Data System (ADS)

Parini, G.; Possa, G.

Two on-line acoustic monitoring techniques for leak detection in feedwater preheaters and boilers of fossil fuel power plants are presented. The leak detection is based on the acoustic noise produced by the turbulent leak outflow. The primary sensors are piezoelectric pressure transducers, installed near the feedwater preheater inlets, in direct contact with the water, or mounted on boiler observation windows. The frequency band of the auscultation ranges from a few kHz, to 10 to 15 kHz. The signals are characterized by their rms value, continuously recorded by means of potentiometric strip chart recorders. The leak occurrence is signalled by the signal rms overcoming predetermined threshold levels. Sensitivity, reliability, acceptance in plant control practice, and costs-benefits balance are satisfactory.

Time-frequency analysis of acoustic signals in the audio-frequency range generated during Hadfield's steel friction

NASA Astrophysics Data System (ADS)

Dobrynin, S. A.; Kolubaev, E. A.; Smolin, A. Yu.; Dmitriev, A. I.; Psakhie, S. G.

2010-07-01

Time-frequency analysis of sound waves detected by a microphone during the friction of Hadfield’s steel has been performed using wavelet transform and window Fourier transform methods. This approach reveals a relationship between the appearance of quasi-periodic intensity outbursts in the acoustic response signals and the processes responsible for the formation of wear products. It is shown that the time-frequency analysis of acoustic emission in a tribosystem can be applied, along with traditional approaches, to studying features in the wear and friction process.

Design of acoustic emission monitoring system based on VC++

NASA Astrophysics Data System (ADS)

Yu, Yang; He, Wei

2015-12-01

At present, a lot of companies at home and abroad have researched and produced a batch of specialized monitoring instruments for acoustic emission (AE). Most of them cost highly and the system function exists in less stable and less portability for the testing environment and transmission distance and other aspects. Depending on the research background and the status quo, a dual channel intelligent acoustic emission monitoring system was designed based on Microsoft Foundation Classes in Visual Studio C++ to solve some of the problems in the acoustic emission research and meet the needs of actual monitoring task. It contains several modules such as main module, acquisition module, signal parameters setting module and so on. It could give out corrosion AE waveform and signal parameters results according to the main menu selected parameters. So the needed information could be extracted from the experiments datum to solve the problem deeply. This soft system is the important part of AE detection g system.

Phenotypic integration and the evolution of signal repertoires: A case study of treefrog acoustic communication.

PubMed

Reichert, Michael S; Höbel, Gerlinde

2018-03-01

Animal signals are inherently complex phenotypes with many interacting parts combining to elicit responses from receivers. The pattern of interrelationships between signal components reflects the extent to which each component is expressed, and responds to selection, either in concert with or independently of others. Furthermore, many species have complex repertoires consisting of multiple signal types used in different contexts, and common morphological and physiological constraints may result in interrelationships extending across the multiple signals in species' repertoires. The evolutionary significance of interrelationships between signal traits can be explored within the framework of phenotypic integration, which offers a suite of quantitative techniques to characterize complex phenotypes. In particular, these techniques allow for the assessment of modularity and integration, which describe, respectively, the extent to which sets of traits covary either independently or jointly. Although signal and repertoire complexity are thought to be major drivers of diversification and social evolution, few studies have explicitly measured the phenotypic integration of signals to investigate the evolution of diverse communication systems. We applied methods from phenotypic integration studies to quantify integration in the two primary vocalization types (advertisement and aggressive calls) in the treefrogs Hyla versicolor , Hyla cinerea, and Dendropsophus ebraccatus . We recorded male calls and calculated standardized phenotypic variance-covariance ( P ) matrices for characteristics within and across call types. We found significant integration across call types, but the strength of integration varied by species and corresponded with the acoustic similarity of the call types within each species. H. versicolor had the most modular advertisement and aggressive calls and the least acoustically similar call types. Additionally, P was robust to changing social competition

Acoustic transistor: Amplification and switch of sound by sound

NASA Astrophysics Data System (ADS)

Liang, Bin; Kan, Wei-wei; Zou, Xin-ye; Yin, Lei-lei; Cheng, Jian-chun

2014-08-01

We designed an acoustic transistor to manipulate sound in a manner similar to the manipulation of electric current by its electrical counterpart. The acoustic transistor is a three-terminal device with the essential ability to use a small monochromatic acoustic signal to control a much larger output signal within a broad frequency range. The output and controlling signals have the same frequency, suggesting the possibility of cascading the structure to amplify an acoustic signal. Capable of amplifying and switching sound by sound, acoustic transistors have various potential applications and may open the way to the design of conceptual devices such as acoustic logic gates.

Airborne DoA estimation of gunshot acoustic signals using drones with application to sniper localization systems

NASA Astrophysics Data System (ADS)

Fernandes, Rigel P.; Ramos, António L. L.; Apolinário, José A.

2017-05-01

Shooter localization systems have been subject of a growing attention lately owing to its wide span of possible applications, e.g., civil protection, law enforcement, and support to soldiers in missions where snipers might pose a serious threat. These devices are based on the processing of electromagnetic or acoustic signatures associated with the firing of a gun. This work is concerned with the latter, where the shooter's position can be obtained based on the estimation of the direction-of-arrival (DoA) of the acoustic components of a gunshot signal (muzzle blast and shock wave). A major limitation of current commercially available acoustic sniper localization systems is the impossibility of finding the shooter's position when one of these acoustic signatures is not detected. This is very likely to occur in real-life situations, especially when the microphones are not in the field of view of the shockwave or when the presence of obstacles like buildings can prevent a direct-path to sensors. This work addresses the problem of DoA estimation of the muzzle blast using a planar array of sensors deployed in a drone. Results supported by actual gunshot data from a realistic setup are very promising and pave the way for the development of enhanced sniper localization systems featuring two main advantages over stationary ones: (1) wider surveillance area; and (2) increased likelihood of a direct-path detection of at least one of the gunshot signals, thereby adding robustness and reliability to the system.

Automated Acoustic Identification of Bats

DTIC Science & Technology

2011-10-01

signals. Other signal sources contribute to the overall acoustic soundscape and interfere with discerning the bat calls from the background signals. In...noises, and the changing soundscape from moving can all exceed at least parts of the signal amplitude of bat calls. The ability to track the trend...results, full-spectrum data also provides an effective voucher for interpretation of the full acoustic soundscape at the time of the recording. Figure

The acoustic structure of male giant panda bleats varies according to intersexual context.

PubMed

Charlton, Benjamin D; Keating, Jennifer L; Rengui, Li; Huang, Yan; Swaisgood, Ronald R

2015-09-01

Although the acoustic structure of mammal vocal signals often varies according to the social context of emission, relatively few mammal studies have examined acoustic variation during intersexual advertisement. In the current study male giant panda bleats were recorded during the breeding season in three behavioural contexts: vocalising alone, during vocal interactions with females outside of peak oestrus, and during vocal interactions with peak-oestrous females. Male bleats produced during vocal interactions with peak-oestrous females were longer in duration and had higher mean fundamental frequency than those produced when males were either involved in a vocal interaction with a female outside of peak oestrus or vocalising alone. In addition, males produced bleats with higher rates of fundamental frequency modulation when they were vocalising alone than when they were interacting with females. These results show that acoustic features of male giant panda bleats have the potential to signal the caller's motivational state, and suggest that males increase the rate of fundamental frequency modulation in bleats when they are alone to maximally broadcast their quality and promote close-range contact with receptive females during the breeding season.

Sparsity-Based Representation for Classification Algorithms and Comparison Results for Transient Acoustic Signals

DTIC Science & Technology

2016-05-01

large but correlated noise and signal interference (i.e., low -rank interference). Another contribution is the implementation of deep learning...representation, low rank, deep learning 52 Tung-Duong Tran-Luu 301-394-3082Unclassified Unclassified Unclassified UU ii Approved for public release; distribution...Classification of Acoustic Transients 6 3.2 Joint Sparse Representation with Low -Rank Interference 7 3.3 Simultaneous Group-and-Joint Sparse Representation

Acoustic logic gates and Boolean operation based on self-collimating acoustic beams

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

Zhang, Ting; Xu, Jian-yi; Cheng, Ying, E-mail: chengying@nju.edu.cn

2015-03-16

The reveal of self-collimation effect in two-dimensional (2D) photonic or acoustic crystals has opened up possibilities for signal manipulation. In this paper, we have proposed acoustic logic gates based on the linear interference of self-collimated beams in 2D sonic crystals (SCs) with line-defects. The line defects on the diagonal of the 2D square SCs are actually functioning as a 3 dB splitter. By adjusting the phase difference between two input signals, the basic Boolean logic functions such as XOR, OR, AND, and NOT are achieved both theoretically and experimentally. Due to the non-diffracting property of self-collimation beams, more complex Boolean logicmore » and algorithms such as NAND, NOR, and XNOR can be realized by cascading the basic logic gates. The achievement of acoustic logic gates and Boolean operation provides a promising approach for acoustic signal computing and manipulations.« less

Transmission acoustic microscopy investigation

NASA Astrophysics Data System (ADS)

Maev, Roman; Kolosov, Oleg; Levin, Vadim; Lobkis, Oleg

The nature of acoustic contrast, i.e. the connection of the amplitude and phase of the output signal of the acoustic microscope with the local values of the acoustic parameters of the sample (density, elasticity, viscosity) is a central problem of acoustic microscopy. A considerable number of studies have been devoted to the formation of the output signal of the reflection scanning acoustic microscope. For the transmission acoustic microscope (TAM) this problem has remained almost unstudied. Experimental investigation of the confocal system of the TAM was carried out on an independently manufactured laboratory mockup of the TAM with the working frequency of the 420 MHz. Acoustic lenses with the radius of curvature of about 500 microns and aperture angle of 45 deg were polished out in the end faces of two cylindrical sound conductors made from Al2O3 single crystals with an axis parallel to the axis C of the crystal (the length of the sound conductor is 20 mm; diameter, 6 mm). At the end faces of the sound conductor, opposite to the lenses, CdS transducers with a diameter of 2 mm were disposed. The electric channel of the TAM provided a possibility for registering the amplitude of the microscope output signal in the case of the dynamic range of the 50 dB.

Multiple-frequency acoustic wave devices for chemical sensing and materials characterization in both gas and liquid phase

DOEpatents

Martin, S.J.; Ricco, A.J.

1993-08-10

A chemical or intrinsic physical property sensor is described comprising: (a) a substrate; (b) an interaction region of said substrate where the presence of a chemical or physical stimulus causes a detectable change in the velocity and/or an attenuation of an acoustic wave traversing said region; and (c) a plurality of paired input and output interdigitated electrodes patterned on the surface of said substrate where each of said paired electrodes has a distinct periodicity, where each of said paired electrodes is comprised of an input and an output electrode; (d) an input signal generation means for transmitting an input signal having a distinct frequency to a specified input interdigitated electrode of said plurality so that each input electrode receives a unique input signal, whereby said electrode responds to said input signal by generating an acoustic wave of a specified frequency, thus, said plurality responds by generating a plurality of acoustic waves of different frequencies; (e) an output signal receiving means for determining an acoustic wave velocity and an amplitude of said acoustic waves at several frequencies after said waves transverses said interaction region and comparing these values to an input acoustic wave velocity and an input acoustic wave amplitude to produce values for perturbations in acoustic wave velocities and for acoustic wave attenuation as a function of frequency, where said output receiving means is individually coupled to each of said output interdigitated electrode; (f) a computer means for analyzing a data stream comprising information from said output receiving means and from said input signal generation means to differentiate a specified response due to a perturbation from a subsequent specified response due to a subsequent perturbation to determine the chemical or intrinsic physical properties desired.

Acoustic emission source localization based on distance domain signal representation

NASA Astrophysics Data System (ADS)

Gawronski, M.; Grabowski, K.; Russek, P.; Staszewski, W. J.; Uhl, T.; Packo, P.

2016-04-01

Acoustic emission is a vital non-destructive testing technique and is widely used in industry for damage detection, localisation and characterization. The latter two aspects are particularly challenging, as AE data are typically noisy. What is more, elastic waves generated by an AE event, propagate through a structural path and are significantly distorted. This effect is particularly prominent for thin elastic plates. In these media the dispersion phenomenon results in severe localisation and characterization issues. Traditional Time Difference of Arrival methods for localisation techniques typically fail when signals are highly dispersive. Hence, algorithms capable of dispersion compensation are sought. This paper presents a method based on the Time - Distance Domain Transform for an accurate AE event localisation. The source localisation is found through a minimization problem. The proposed technique focuses on transforming the time signal to the distance domain response, which would be recorded at the source. Only, basic elastic material properties and plate thickness are used in the approach, avoiding arbitrary parameters tuning.

Experimental Research Into Generation of Acoustic Emission Signals in the Process of Friction of Hadfield Steel Single Crystals

NASA Astrophysics Data System (ADS)

Lychagin, D. V.; Filippov, A. V.; Novitskaia, O. S.; Kolubaev, E. A.; Sizova, O. V.

2016-08-01

The results of experimental research into dry sliding friction of Hadfield steel single crystals involving registration of acoustic emission are presented in the paper. The images of friction surfaces of Hadfield steel single crystals and wear grooves of the counterbody surface made after completion of three serial experiments conducted under similar conditions and friction regimes are given. The relation of the acoustic emission waveform envelope to the changing friction factor is revealed. Amplitude-frequency characteristics of acoustic emission signal frames are determined on the base of Fast Fourier Transform and Short Time Fourier Transform during the run-in stage of tribounits and in the process of stable friction.

Acoustic communication in plant-animal interactions.

PubMed

Schöner, Michael G; Simon, Ralph; Schöner, Caroline R

2016-08-01

Acoustic communication is widespread and well-studied in animals but has been neglected in other organisms such as plants. However, there is growing evidence for acoustic communication in plant-animal interactions. While knowledge about active acoustic signalling in plants (i.e. active sound production) is still in its infancy, research on passive acoustic signalling (i.e. reflection of animal sounds) revealed that bat-dependent plants have adapted to the bats' echolocation systems by providing acoustic reflectors to attract their animal partners. Understanding the proximate mechanisms and ultimate causes of acoustic communication will shed light on an underestimated dimension of information transfer between plants and animals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Based on optical fiber Michelson interferometer for acoustic emission detection experimental research

NASA Astrophysics Data System (ADS)

Liang, Yijun; Qu, Dandan; Deng, Hu

2013-08-01

A type of Michelson interferometer with two optical fiber loop reflectors acoustic emission sensor is proposed in the article to detect the vibrations produced by ultrasonic waves propagating in a solid body. Two optical fiber loop reflectors are equivalent to the sensing arm and the reference arm instead of traditional Michelson interferometer end reflecter Theoretical analyses indicate that the sensitivity of the system has been remarkably increased because of the decrease of the losses of light energy. The best operating point of optical fiber sensor is fixed by theoretical derivation and simulation of computer, and the signal frequency which is detected by the sensor is the frequency of input signal. PZT (Piezoelectric Ceramic) is powered by signal generator as known ultrasonic source, The Polarization controller is used to make the reflected light interference，The fiber length is changed by adjusting the DC voltage on the PZT with the fiber loop to make the sensor system response that ΔΦ is closed to π/2. the signal basis frequency detected by the sensor is the frequency of the input signal. Then impacts the surface of the marble slab with home-made mechanical acoustic emission source. And detect it. and then the frequency characteristic of acoustic emission signal is obtained by Fourier technique. The experimental results indicate that the system can identify the frequency characteristic of acoustic emission signal, and it can be also used to detect the surface feeble vibration which is generated by ultrasonic waves propagating in material structure.

Electromotile hearing: Acoustic tones mask psychophysical response to high-frequency electrical stimulation of intact guinea pig cochleaea)

PubMed Central

Le Prell, Colleen G.; Kawamoto, Kohei; Raphael, Yehoash; Dolan, David F.

2011-01-01

When sinusoidal electric stimulation is applied to the intact cochlea, a frequency-specific acoustic emission can be recorded in the ear canal. Acoustic emissions are produced by basilar membrane motion, and have been used to suggest a corresponding acoustic sensation termed “electromotile hearing.” Electromotile hearing has been specifically attributed to electric stimulation of outer hair cells in the intact organ of Corti. To determine the nature of the auditory perception produced by electric stimulation of a cochlea with intact outer hair cells, we tested guinea pigs in a psychophysical task. First, subjects were trained to report detection of sinusoidal acoustic stimuli and dynamic range was assessed using response latency. Subjects were then implanted with a ball electrode placed into scala tympani. Following the surgical implant procedure, subjects were transferred to a task in which acoustic signals were replaced by sinusoidal electric stimulation, and dynamic range was assessed again. Finally, the ability of acoustic pure-tone stimuli to mask the detection of the electric signals was assessed. Based on the masking effects, we conclude that sinusoidal electric stimulation of the intact cochlea results in perception of a tonal (rather than a broad-band or noisy) sound at a frequency of 8 kHz or above. PMID:17225416

Acoustic investigation of the aperture dynamics of an elastic membrane closing an overpressurized cylindrical cavity

NASA Astrophysics Data System (ADS)

Sánchez, Claudia; Vidal, Valérie; Melo, Francisco

2015-08-01

We report an experimental study of the acoustic signal produced by the rupture of an elastic membrane that initially closes a cylindrical overpressurized cavity. This configuration has been recently used as an experimental model system for the investigation of the acoustic emission from the bursting of elongated gas bubbles rising in a conduit. Here, we investigate the effect of the membrane rupture dynamics on the acoustic signal produced by the pressure release by changing the initial tension of the membrane. The initial overpressure in the cavity is fixed at a value such that the system remains in the linear acoustic regime. For large initial membrane deformation, the rupture time τ rup is small compared to the wave propagation time in the cavity and the pressure wave inside the conduit can be fully captured by the linear theory. For low membrane tension, a hole is pierced in the membrane but its rupture does not occur. For intermediate deformation, finally, the rupture progresses in two steps: first the membrane opens slowly; then, after reaching a critical size, the rupture accelerates. A transversal wave is excited along the membrane surface. The characteristic signature of each opening dynamics on the acoustic emission is described.

Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.

PubMed

Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A

2014-11-24

Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications.

A test of the acoustic adaptation hypothesis in four species of marmots.

PubMed

Daniel; Blumstein

1998-12-01

Acoustic signals must be transmitted from a signaller to a receiver during which time they become modified. The acoustic adaptation hypothesis suggests that selection should shape the structure of long-distance signals to maximize transmission through different habitats. A specific prediction of the acoustic adaptation hypothesis is that long-distance signals of animals in their native habitat are expected to change less during transmission than non-native signals within that habitat. This prediction was tested using the alarm calls of four species of marmots that live in acoustically different habitats and produce species-specific, long-distance alarm vocalizations: yellow-bellied marmot, Marmota flaviventris; Olympic marmot, M. olympus; hoary marmot, M. caligata; and woodchuck, M. monax. By doing so, we evaluated the relative importance the acoustic environment plays on selecting for divergent marmot alarm calls. Representative alarm calls of the four species were broadcast and rerecorded in each species' habitat at four distances from a source. Rerecorded, and therefore degraded alarm calls, were compared to undegraded calls using spectrogram correlation. If each species' alarm call was transmitted with less overall degradation in its own environment, a significant interaction between species' habitat and species' call type would be expected. Transmission fidelity at each of four distances was treated as a multivariate response and differences among habitat and call type were tested in a two-way MANOVA. Although significant overall differences in the transmission properties of the habitats were found, and significant overall differences in the transmission properties of the call types were found, there was no significant interaction between habitat and call type. Thus, the evidence did not support the acoustic adaptation hypothesis for these marmot species. Factors other than maximizing long-distance transmission through the environment may be important in the

ACOUSTIC LOCATION OF LEAKS IN PRESSURIZED UNDERGROUND PETROLEUM PIPELINES

EPA Science Inventory

Experiments were conducted at the UST Test Apparatus Pipeline in which three acoustic sensors separated by a maximum distance of 38 m (125-ft) were used to monitor signals produced by 3.0-, 1.5-, and 1.0-gal/h leaks in the wall of a 2-in.-diameter pressurized petroleum pipeline. ...

An acoustic analysis of laughter produced by congenitally deaf and normally hearing college students1

PubMed Central

Makagon, Maja M.; Funayama, E. Sumie; Owren, Michael J.

2008-01-01

Relatively few empirical data are available concerning the role of auditory experience in nonverbal human vocal behavior, such as laughter production. This study compared the acoustic properties of laughter in 19 congenitally, bilaterally, and profoundly deaf college students and in 23 normally hearing control participants. Analyses focused on degree of voicing, mouth position, air-flow direction, temporal features, relative amplitude, fundamental frequency, and formant frequencies. Results showed that laughter produced by the deaf participants was fundamentally similar to that produced by the normally hearing individuals, which in turn was consistent with previously reported findings. Finding comparable acoustic properties in the sounds produced by deaf and hearing vocalizers confirms the presumption that laughter is importantly grounded in human biology, and that auditory experience with this vocalization is not necessary for it to emerge in species-typical form. Some differences were found between the laughter of deaf and hearing groups; the most important being that the deaf participants produced lower-amplitude and longer-duration laughs. These discrepancies are likely due to a combination of the physiological and social factors that routinely affect profoundly deaf individuals, including low overall rates of vocal fold use and pressure from the hearing world to suppress spontaneous vocalizations. PMID:18646991

Two-dimensional directional synthetic aperture focusing technique using acoustic-resolution photoacoustic microscopy

NASA Astrophysics Data System (ADS)

Jeon, Seungwan; Park, Jihoon; Kim, Chulhong

2018-02-01

Photoacoustic microscopy (PAM) is a hybrid imaging technology using optical illumination and acoustic detection. PAM is divided into two types: optical-resolution PAM (OR-PAM) and acoustic-resolution photoacoustic microscopy (AR-PAM). Among them, AR-PAM has a great advantage in the penetration depth compared to OR-PAM because ARPAM relies on the acoustic focus, which is much less scattered in biological tissue than optical focus. However, because the acoustic focus is not as tight as the optical focus with a same numerical aperture (NA), the AR-PAM requires acoustic NA higher than optical NA. The high NA of the acoustic focus produces good image quality in the focal zone, but significantly degrades spatial resolution and signal-to-noise ratio (SNR) in the out-of-focal zone. To overcome the problem, synthetic aperture focusing technique (SAFT) has been introduced. SAFT improves the degraded image quality in terms of both SNR and spatial resolution in the out-of-focus zone by calculating the time delay of the corresponding signals and combining them. To extend the dimension of correction effect, several 2D SAFTs have been introduced, but there was a problem that the conventional 2D SAFTs cannot improve the degraded SNR and resolution as 1D SAFT can do. In this study, we proposed a new 2D SAFT that can compensate the distorted signals in x and y directions while maintaining the correction performance as the 1D SAFT.

The effect of climate on acoustic signals: does atmospheric sound absorption matter for bird song and bat echolocation?

PubMed

Snell-Rood, Emilie C

2012-02-01

The divergence of signals along ecological gradients may lead to speciation. The current research tests the hypothesis that variation in sound absorption selects for divergence in acoustic signals along climatic gradients, which has implications for understanding not only diversification, but also how organisms may respond to climate change. Because sound absorption varies with temperature, humidity, and the frequency of sound, individuals or species may vary signal structure with changes in climate over space or time. In particular, signals of lower frequency, narrower bandwidth, and longer duration should be more detectable in environments with high sound absorption. Using both North American wood warblers (Parulidae) and bats of the American Southwest, this work found evidence of associations between signal structure and sound absorption. Warbler species with higher mean absorption across their range were more likely to have narrow bandwidth songs. Bat species found in higher absorption habitats were more likely to have lower frequency echolocation calls. In addition, bat species changed echolocation call structure across seasons, using longer duration, lower frequency calls in the higher absorption rainy season. These results suggest that signals may diverge along climatic gradients due to variation in sound absorption, although the effects of absorption are modest. © 2012 Acoustical Society of America

Punch stretching process monitoring using acoustic emission signal analysis. II - Application of frequency domain deconvolution

NASA Technical Reports Server (NTRS)

Liang, Steven Y.; Dornfeld, David A.; Nickerson, Jackson A.

1987-01-01

The coloring effect on the acoustic emission signal due to the frequency response of the data acquisition/processing instrumentation may bias the interpretation of AE signal characteristics. In this paper, a frequency domain deconvolution technique, which involves the identification of the instrumentation transfer functions and multiplication of the AE signal spectrum by the inverse of these system functions, has been carried out. In this way, the change in AE signal characteristics can be better interpreted as the result of the change in only the states of the process. Punch stretching process was used as an example to demonstrate the application of the technique. Results showed that, through the deconvolution, the frequency characteristics of AE signals generated during the stretching became more distinctive and can be more effectively used as tools for process monitoring.

Acoustics of contrastive prosody in children

NASA Astrophysics Data System (ADS)

Patel, Rupal; Piel, Jordan; Grigos, Maria

2005-04-01

Empirical data on the acoustics of prosodic control in children is limited, particularly for linguistically contrastive tasks. Twelve children aged 4, 7, and 11 years were asked to produce two utterances ``Show Bob a bot'' (voiced consonants) and ``Show Pop a pot'' (voiceless consonants) 10 times each with emphasis placed on the second word (Bob/Pop) and 10 times with emphasis placed on the last word (bot/pot). A total of 40 utterances were analyzed per child. The following acoustic measures were obtained for each word within each utterance: average fundamental frequency (f0), peak f0, average intensity, peak intensity, and duration. Preliminary results suggest that 4 year olds are unable to modulate prosodic cues to signal the linguistic contrast. The 7 year olds, however, not only signaled the appropriate stress location, but did so with the most contrastive differences in f0, intensity, and duration, of all age groups. Prosodic differences between stressed and unstressed words were more pronounced for the utterance with voiced consonants. These findings suggest that the acoustics of linguistic prosody begin to differentiate between age 4 and 7 and may be highly influenced by changes in physiological control and flexibility that may also affect segmental features.

Artillery/mortar type classification based on detected acoustic transients

NASA Astrophysics Data System (ADS)

Morcos, Amir; Grasing, David; Desai, Sachi

2008-04-01

Feature extraction methods based on the statistical analysis of the change in event pressure levels over a period and the level of ambient pressure excitation facilitate the development of a robust classification algorithm. The features reliably discriminates mortar and artillery variants via acoustic signals produced during the launch events. Utilizing acoustic sensors to exploit the sound waveform generated from the blast for the identification of mortar and artillery variants as type A, etcetera through analysis of the waveform. Distinct characteristics arise within the different mortar/artillery variants because varying HE mortar payloads and related charges emphasize varying size events at launch. The waveform holds various harmonic properties distinct to a given mortar/artillery variant that through advanced signal processing and data mining techniques can employed to classify a given type. The skewness and other statistical processing techniques are used to extract the predominant components from the acoustic signatures at ranges exceeding 3000m. Exploiting these techniques will help develop a feature set highly independent of range, providing discrimination based on acoustic elements of the blast wave. Highly reliable discrimination will be achieved with a feed-forward neural network classifier trained on a feature space derived from the distribution of statistical coefficients, frequency spectrum, and higher frequency details found within different energy bands. The processes that are described herein extend current technologies, which emphasis acoustic sensor systems to provide such situational awareness.

Signal identification in acoustic emission monitoring of fatigue cracking in steel bridges

NASA Astrophysics Data System (ADS)

Yu, Jianguo P.; Ziehl, Paul; Pollock, Adrian

2012-04-01

Signal identification including noise filtering and reduction of acquired signals is needed to achieve efficient and accurate data interpretation for remote acoustic emission (AE) monitoring of in-service steel bridges. Noise filtering may ensure that genuine hits from crack growth are involved in the estimation of fatigue damage and remaining fatigue life. Reduction of the data quantity is desirable for the sensing system to conserve energy in the data transmission and processing procedures. Identification and categorization of acquired signals is a promising approach to effectively filter and reduce AE data in the application of bridge monitoring. In this study an investigation on waveform features (time domain and frequency domain) and relevant filters is carried out using the results from AE monitored fatigue tests. It is verified that duration-amplitude (D-A) filters are effective to discriminate against noise for results of steel fatigue tests. The study is helpful to find an appropriate AE data filtering protocol for field implementations.

Effect of reflected and refracted signals on coherent underwater acoustic communication: results from the Kauai experiment (KauaiEx 2003).

PubMed

Rouseff, Daniel; Badiey, Mohsen; Song, Aijun

2009-11-01

The performance of a communications equalizer is quantified in terms of the number of acoustic paths that are treated as usable signal. The analysis uses acoustical and oceanographic data collected off the Hawaiian Island of Kauai. Communication signals were measured on an eight-element vertical array at two different ranges, 1 and 2 km, and processed using an equalizer based on passive time-reversal signal processing. By estimating the Rayleigh parameter, it is shown that all paths reflected by the sea surface at both ranges undergo incoherent scattering. It is demonstrated that some of these incoherently scattered paths are still useful for coherent communications. At range of 1 km, optimal communications performance is achieved when six acoustic paths are retained and all paths with more than one reflection off the sea surface are rejected. Consistent with a model that ignores loss from near-surface bubbles, the performance improves by approximately 1.8 dB when increasing the number of retained paths from four to six. The four-path results though are more stable and require less frequent channel estimation. At range of 2 km, ray refraction is observed and communications performance is optimal when some paths with two sea-surface reflections are retained.

Acoustic Transmitters for Underwater Neutrino Telescopes

PubMed Central

Ardid, Miguel; Martínez-Mora, Juan A.; Bou-Cabo, Manuel; Larosa, Giuseppina; Adrián-Martínez, Silvia; Llorens, Carlos D.

2012-01-01

In this paper acoustic transmitters that were developed for use in underwater neutrino telescopes are presented. Firstly, an acoustic transceiver has been developed as part of the acoustic positioning system of neutrino telescopes. These infrastructures are not completely rigid and require a positioning system in order to monitor the position of the optical sensors which move due to sea currents. To guarantee a reliable and versatile system, the transceiver has the requirements of reduced cost, low power consumption, high pressure withstanding (up to 500 bars), high intensity for emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring and processing received signals. Secondly, a compact acoustic transmitter array has been developed for the calibration of acoustic neutrino detection systems. The array is able to mimic the signature of ultra-high-energy neutrino interaction in emission directivity and signal shape. The technique of parametric acoustic sources has been used to achieve the proposed aim. The developed compact array has practical features such as easy manageability and operation. The prototype designs and the results of different tests are described. The techniques applied for these two acoustic systems are so powerful and versatile that may be of interest in other marine applications using acoustic transmitters. PMID:22666022

Perceived Synchrony of Frog Multimodal Signal Components Is Influenced by Content and Order.

PubMed

Taylor, Ryan C; Page, Rachel A; Klein, Barrett A; Ryan, Michael J; Hunter, Kimberly L

2017-10-01

Multimodal signaling is common in communication systems. Depending on the species, individual signal components may be produced synchronously as a result of physiological constraint (fixed) or each component may be produced independently (fluid) in time. For animals that rely on fixed signals, a basic prediction is that asynchrony between the components should degrade the perception of signal salience, reducing receiver response. Male túngara frogs, Physalaemus pustulosus, produce a fixed multisensory courtship signal by vocalizing with two call components (whines and chucks) and inflating a vocal sac (visual component). Using a robotic frog, we tested female responses to variation in the temporal arrangement between acoustic and visual components. When the visual component lagged a complex call (whine + chuck), females largely rejected this asynchronous multisensory signal in favor of the complex call absent the visual cue. When the chuck component was removed from one call, but the robofrog inflation lagged the complex call, females responded strongly to the asynchronous multimodal signal. When the chuck component was removed from both calls, females reversed preference and responded positively to the asynchronous multisensory signal. When the visual component preceded the call, females responded as often to the multimodal signal as to the call alone. These data show that asynchrony of a normally fixed signal does reduce receiver responsiveness. The magnitude and overall response, however, depend on specific temporal interactions between the acoustic and visual components. The sensitivity of túngara frogs to lagging visual cues, but not leading ones, and the influence of acoustic signal content on the perception of visual asynchrony is similar to those reported in human psychophysics literature. Virtually all acoustically communicating animals must conduct auditory scene analyses and identify the source of signals. Our data suggest that some basic

Characterisation of bubbles in liquids using acoustic techniques

NASA Astrophysics Data System (ADS)

Ramble, David Gary

1997-12-01

This thesis is concerned with the characterisation of air bubbles in a liquid through the use of a range of acoustic techniques, with the ultimate aim of minimising the ambiguity of the result and the complexity of the task. A bubble is particularly amenable to detection by using acoustical methods because there usually exists a large acoustic impedance mismatch between the gas/vapour inside the bubble and that of the surrounding liquid. The bubble also behaves like a single degree-of-freedom oscillator when excited, and as such exhibits a well-defined resonance frequency which is related to its radius. Though techniques which exploit this resonance property of the bubble are straightforward to apply, the results are prone to ambiguities as larger bubbles can geometrically scatter more sound than a smaller resonant bubble. However, these drawbacks can be overcome by using acoustical methods which make use of the nonlinear behaviour of bubbles. A particular nonlinear technique monitors the second harmonic emission of the bubble which is a global maximum at resonance. In addition, a two- frequency excitation technique is used which involves exciting the bubble with a fixed high frequency signal (the imaging signal, ωi) of the order of megahertz, and a lower variable frequency (the pumping signal, ωp) which is tuned to the bubble's resonance. The bubble couples these two sound fields together to produce sum-and-difference terms which peak at resonance. The two most promising combination frequency signals involve the coupling of the bubble's fundamental with the imaging frequency to give rise to a ωi+ωp signal, and the coupling of a subharmonic signal at half the resonance frequency of the bubble to give rise to a ωi/pmωp/2 signal. Initially, theory is studied which outlines the advantages and disadvantages of each of the acoustic techniques available. Experiments are then conducted in a large tank of water on simple bubble populations, ranging from stationary

Virtual Acoustics: Evaluation of Psychoacoustic Parameters

NASA Technical Reports Server (NTRS)

Begault, Durand R.; Null, Cynthia H. (Technical Monitor)

1997-01-01

Current virtual acoustic displays for teleconferencing and virtual reality are usually limited to very simple or non-existent renderings of reverberation, a fundamental part of the acoustic environmental context that is encountered in day-to-day hearing. Several research efforts have produced results that suggest that environmental cues dramatically improve perceptual performance within virtual acoustic displays, and that is possible to manipulate signal processing parameters to effectively reproduce important aspects of virtual acoustic perception in real-time. However, the computational resources for rendering reverberation remain formidable. Our efforts at NASA Ames have been focused using a several perceptual threshold metrics, to determine how various "trade-offs" might be made in real-time acoustic rendering. This includes both original work and confirmation of existing data that was obtained in real rather than virtual environments. The talk will consider the importance of using individualized versus generalized pinnae cues (the "Head-Related Transfer Function"); the use of head movement cues; threshold data for early reflections and late reverberation; and consideration of the necessary accuracy for measuring and rendering octave-band absorption characteristics of various wall surfaces. In addition, a consideration of the analysis-synthesis of the reverberation within "everyday spaces" (offices, conference rooms) will be contrasted to the commonly used paradigm of concert hall spaces.

Surface acoustic wave coding for orthogonal frequency coded devices

NASA Technical Reports Server (NTRS)

Malocha, Donald (Inventor); Kozlovski, Nikolai (Inventor)

2011-01-01

Methods and systems for coding SAW OFC devices to mitigate code collisions in a wireless multi-tag system. Each device producing plural stepped frequencies as an OFC signal with a chip offset delay to increase code diversity. A method for assigning a different OCF to each device includes using a matrix based on the number of OFCs needed and the number chips per code, populating each matrix cell with OFC chip, and assigning the codes from the matrix to the devices. The asynchronous passive multi-tag system includes plural surface acoustic wave devices each producing a different OFC signal having the same number of chips and including a chip offset time delay, an algorithm for assigning OFCs to each device, and a transceiver to transmit an interrogation signal and receive OFC signals in response with minimal code collisions during transmission.

Photo-acoustic and video-acoustic methods for sensing distant sound sources

NASA Astrophysics Data System (ADS)

Slater, Dan; Kozacik, Stephen; Kelmelis, Eric

2017-05-01

Long range telescopic video imagery of distant terrestrial scenes, aircraft, rockets and other aerospace vehicles can be a powerful observational tool. But what about the associated acoustic activity? A new technology, Remote Acoustic Sensing (RAS), may provide a method to remotely listen to the acoustic activity near these distant objects. Local acoustic activity sometimes weakly modulates the ambient illumination in a way that can be remotely sensed. RAS is a new type of microphone that separates an acoustic transducer into two spatially separated components: 1) a naturally formed in situ acousto-optic modulator (AOM) located within the distant scene and 2) a remote sensing readout device that recovers the distant audio. These two elements are passively coupled over long distances at the speed of light by naturally occurring ambient light energy or other electromagnetic fields. Stereophonic, multichannel and acoustic beam forming are all possible using RAS techniques and when combined with high-definition video imagery it can help to provide a more cinema like immersive viewing experience. A practical implementation of a remote acousto-optic readout device can be a challenging engineering problem. The acoustic influence on the optical signal is generally weak and often with a strong bias term. The optical signal is further degraded by atmospheric seeing turbulence. In this paper, we consider two fundamentally different optical readout approaches: 1) a low pixel count photodiode based RAS photoreceiver and 2) audio extraction directly from a video stream. Most of our RAS experiments to date have used the first method for reasons of performance and simplicity. But there are potential advantages to extracting audio directly from a video stream. These advantages include the straight forward ability to work with multiple AOMs (useful for acoustic beam forming), simpler optical configurations, and a potential ability to use certain preexisting video recordings. However

Ecological Insights from Pelagic Habitats Acquired Using Active Acoustic Techniques.

PubMed

Benoit-Bird, Kelly J; Lawson, Gareth L

2016-01-01

Marine pelagic ecosystems present fascinating opportunities for ecological investigation but pose important methodological challenges for sampling. Active acoustic techniques involve producing sound and receiving signals from organisms and other water column sources, offering the benefit of high spatial and temporal resolution and, via integration into different platforms, the ability to make measurements spanning a range of spatial and temporal scales. As a consequence, a variety of questions concerning the ecology of pelagic systems lend themselves to active acoustics, ranging from organism-level investigations and physiological responses to the environment to ecosystem-level studies and climate. As technologies and data analysis methods have matured, the use of acoustics in ecological studies has grown rapidly. We explore the continued role of active acoustics in addressing questions concerning life in the ocean, highlight creative applications to key ecological themes ranging from physiology and behavior to biogeography and climate, and discuss emerging avenues where acoustics can help determine how pelagic ecosystems function.

Acoustic duetting in Drosophila virilis relies on the integration of auditory and tactile signals

PubMed Central

LaRue, Kelly M; Clemens, Jan; Berman, Gordon J; Murthy, Mala

2015-01-01

Many animal species, including insects, are capable of acoustic duetting, a complex social behavior in which males and females tightly control the rate and timing of their courtship song syllables relative to each other. The mechanisms underlying duetting remain largely unknown across model systems. Most studies of duetting focus exclusively on acoustic interactions, but the use of multisensory cues should aid in coordinating behavior between individuals. To test this hypothesis, we develop Drosophila virilis as a new model for studies of duetting. By combining sensory manipulations, quantitative behavioral assays, and statistical modeling, we show that virilis females combine precisely timed auditory and tactile cues to drive song production and duetting. Tactile cues delivered to the abdomen and genitalia play the larger role in females, as even headless females continue to coordinate song production with courting males. These data, therefore, reveal a novel, non-acoustic, mechanism for acoustic duetting. Finally, our results indicate that female-duetting circuits are not sexually differentiated, as males can also produce ‘female-like’ duets in a context-dependent manner. DOI: http://dx.doi.org/10.7554/eLife.07277.001 PMID:26046297

Method and apparatus of spectro-acoustically enhanced ultrasonic detection for diagnostics

DOEpatents

Vo-Dinh, Tuan; Norton, Stephen J.

2001-01-01

An apparatus for detecting a discontinuity in a material includes a source of electromagnetic radiation has a wavelength and an intensity sufficient to induce an enhancement in contrast between a manifestation of an acoustic property in the material and of the acoustic property in the discontinuity, as compared to when the material is not irradiated by the electromagnetic radiation. An acoustic emitter directs acoustic waves to the discontinuity in the material. The acoustic waves have a sensitivity to the acoustic property. An acoustic receiver receives the acoustic waves generated by the acoustic emitter after the acoustic waves have interacted with the material and the discontinuity. The acoustic receiver also generates a signal representative of the acoustic waves received by the acoustic receiver. A processor, in communication with the acoustic receiver and responsive to the signal generated by the acoustic receiver, is programmed to generate informational output about the discontinuity based on the signal generated by the acoustic receiver.

How do "mute" cicadas produce their calling songs?

PubMed

Luo, Changqing; Wei, Cong; Nansen, Christian

2015-01-01

Insects have evolved a variety of structures and mechanisms to produce sounds, which are used for communication both within and between species. Among acoustic insects, cicada males are particularly known for their loud and diverse sounds which function importantly in communication. The main method of sound production in cicadas is the tymbal mechanism, and a relative small number of cicada species possess both tymbal and stridulatory organs. However, cicadas of the genus Karenia do not have any specialized sound-producing structures, so they are referred to as "mute". This denomination is quite misleading, as they indeed produce sounds. Here, we investigate the sound-producing mechanism and acoustic communication of the "mute" cicada, Karenia caelatata, and discover a new sound-production mechanism for cicadas: i.e., K. caelatata produces impact sounds by banging the forewing costa against the operculum. The temporal, frequency and amplitude characteristics of the impact sounds are described. Morphological studies and reflectance-based analyses reveal that the structures involved in sound production of K. caelatata (i.e., forewing, operculum, cruciform elevation, and wing-holding groove on scutellum) are all morphologically modified. Acoustic playback experiments and behavioral observations suggest that the impact sounds of K. caelatata are used in intraspecific communication and function as calling songs. The new sound-production mechanism expands our knowledge on the diversity of acoustic signaling behavior in cicadas and further underscores the need for more bioacoustic studies on cicadas which lack tymbal mechanism.

Portable Multi Hydrophone Array for Field and Laboratory Measurements of Odontocete Acoustic Signals

DTIC Science & Technology

2015-09-30

bottlenose dolphin and a false killer whale as well as other species such as the Risso’s dolphin . We are currently comparing various file types and methods...echolocation abilities of a Risso’s dolphin are currently being reviewed for publication. 3 The hook detection study recordings are being analyzed for basic...element array in order to obtain horizontal and vertical beam patterns of acoustic signals of a false killer whale and a bottlenose dolphin . The data

Cavitation controlled acoustic probe for fabric spot cleaning and moisture monitoring

DOEpatents

Sheen, Shuh-Haw; Chien, Hual-Te; Raptis, Apostolos C.

1997-01-01

A method and apparatus are provided for monitoring a fabric. An acoustic probe generates acoustic waves relative to the fabric. An acoustic sensor, such as an accelerometer is coupled to the acoustic probe for generating a signal representative of cavitation activity in the fabric. The generated cavitation activity representative signal is processed to indicate moisture content of the fabric. A feature of the invention is a feedback control signal is generated responsive to the generated cavitation activity representative signal. The feedback control signal can be used to control the energy level of the generated acoustic waves and to control the application of a cleaning solution to the fabric.

Processing of simple and complex acoustic signals in a tonotopically organized ear

PubMed Central

Hummel, Jennifer; Wolf, Konstantin; Kössl, Manfred; Nowotny, Manuela

2014-01-01

Processing of complex signals in the hearing organ remains poorly understood. This paper aims to contribute to this topic by presenting investigations on the mechanical and neuronal response of the hearing organ of the tropical bushcricket species Mecopoda elongata to simple pure tone signals as well as to the conspecific song as a complex acoustic signal. The high-frequency hearing organ of bushcrickets, the crista acustica (CA), is tonotopically tuned to frequencies between about 4 and 70 kHz. Laser Doppler vibrometer measurements revealed a strong and dominant low-frequency-induced motion of the CA when stimulated with either pure tone or complex stimuli. Consequently, the high-frequency distal area of the CA is more strongly deflected by low-frequency-induced waves than by high-frequency-induced waves. This low-frequency dominance will have strong effects on the processing of complex signals. Therefore, we additionally studied the neuronal response of the CA to native and frequency-manipulated chirps. Again, we found a dominant influence of low-frequency components within the conspecific song, indicating that the mechanical vibration pattern highly determines the neuronal response of the sensory cells. Thus, we conclude that the encoding of communication signals is modulated by ear mechanics. PMID:25339727

Acoustic resonance phase locked photoacoustic spectrometer

DOEpatents

Pilgrim, Jeffrey S.; Bomse, David S.; Silver, Joel A.

2003-08-19

A photoacoustic spectroscopy method and apparatus for maintaining an acoustic source frequency on a sample cell resonance frequency comprising: providing an acoustic source to the sample cell to generate a photoacoustic signal, the acoustic source having a source frequency; continuously measuring detection phase of the photoacoustic signal with respect to source frequency or a harmonic thereof; and employing the measured detection phase to provide magnitude and direction for correcting the source frequency to the resonance frequency.

Problems Associated with Statistical Pattern Recognition of Acoustic Emission Signals in a Compact Tension Fatigue Specimen

NASA Technical Reports Server (NTRS)

Hinton, Yolanda L.

1999-01-01

Acoustic emission (AE) data were acquired during fatigue testing of an aluminum 2024-T4 compact tension specimen using a commercially available AE system. AE signals from crack extension were identified and separated from noise spikes, signals that reflected from the specimen edges, and signals that saturated the instrumentation. A commercially available software package was used to train a statistical pattern recognition system to classify the signals. The software trained a network to recognize signals with a 91-percent accuracy when compared with the researcher's interpretation of the data. Reasons for the discrepancies are examined and it is postulated that additional preprocessing of the AE data to focus on the extensional wave mode and eliminate other effects before training the pattern recognition system will result in increased accuracy.

Bilinear Time-frequency Analysis for Lamb Wave Signal Detected by Electromagnetic Acoustic Transducer

NASA Astrophysics Data System (ADS)

Sun, Wenxiu; Liu, Guoqiang; Xia, Hui; Xia, Zhengwu

2018-03-01

Accurate acquisition of the detection signal travel time plays a very important role in cross-hole tomography. The experimental platform of aluminum plate under the perpendicular magnetic field is established and the bilinear time-frequency analysis methods, Wigner-Ville Distribution (WVD) and the pseudo-Wigner-Ville distribution (PWVD), are applied to analyse the Lamb wave signals detected by electromagnetic acoustic transducer (EMAT). By extracting the same frequency component of the time-frequency spectrum as the excitation frequency, the travel time information can be obtained. In comparison with traditional linear time-frequency analysis method such as short-time Fourier transform (STFT), the bilinear time-frequency analysis method PWVD is more appropriate in extracting travel time and recognizing patterns of Lamb wave.

System and method for sonic wave measurements using an acoustic beam source

DOEpatents

Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

2015-08-11

A method and system for investigating structure near a borehole are described herein. The method includes generating an acoustic beam by an acoustic source; directing at one or more azimuthal angles the acoustic beam towards a selected location in a vicinity of a borehole; receiving at one or more receivers an acoustic signal, the acoustic signal originating from a reflection or a refraction of the acoustic wave by a material at the selected location; and analyzing the received acoustic signal to characterize features of the material around the borehole.

Study of opto-acoustic communication between air and underwater carrier

NASA Astrophysics Data System (ADS)

Zong, Si-Guang; Liu, Tao; Cao, Jing; He, Qi-Yi

2018-02-01

How to solve the communication problem to the underwater target has turned into one of the subjects that the militarists of all over the world commonly concern. Laser-induced acoustic signal is a new approach for underwater acoustic source, which has much virtue such as high intensity, short pulse and broad frequency. The paper studies the opto-acoustic communication method. The acoustic signal characteristic of laser-induced breakdown is studied and corresponding theory model is systemically analyzed. The opto-acoustic communication experimental measure investigation is formed with the high power laser, water tank and high frequency hydrophone. The characteristic of acoustic signal is analyzed, such as intensity and frequency. This makes a stride for pursing the feasibility of laser-acoustic underwater communication.

Coupled High Speed Imaging and Seismo-Acoustic Recordings of Strombolian Explosions at Etna, July 2014: Implications for Source Processes and Signal Inversions.

NASA Astrophysics Data System (ADS)

Taddeucci, J.; Del Bello, E.; Scarlato, P.; Ricci, T.; Andronico, D.; Kueppers, U.; Cannata, A.; Sesterhenn, J.; Spina, L.

2015-12-01

Seismic and acoustic surveillance is routinely performed at several persistent activity volcanoes worldwide. However, interpretation of the signals associated with explosive activity is still equivocal, due to both source variability and the intrinsically limited information carried by the waves. Comparison and cross-correlation of the geophysical quantities with other information in general and visual recording in particular is therefore actively sought. At Etna (Italy) in July 2014, short-lived Strombolian explosions ejected bomb- to lapilli-sized, molten pyroclasts at a remarkably repeatable time interval of about two seconds, offering a rare occasion to systematically investigate the seismic and acoustic fields radiated by this common volcanic source. We deployed FAMoUS (FAst, MUltiparametric Setup for the study of explosive activity) at 260 meters from the vents, recording more than 60 explosions in thermal and visible high-speed videos (50 to 500 frames per second) and broadband seismic and acoustic instruments (1 to 10000 Hz for the acoustic and from 0.01 to 30 Hz for the seismic). Analysis of this dataset highlights nonlinear relationships between the exit velocity and mass of ejecta and the amplitude and frequency of the acoustic signals. It also allows comparing different methods to estimate source depth, and to validate existing theory on the coupling of airwaves with ground motion.

Skull's acoustic attenuation and dispersion modeling on photoacoustic signal

NASA Astrophysics Data System (ADS)

Mohammadi, Leila; Behnam, Hamid; Tavakkoli, Jahan; Nasiriavanaki, Mohammadreza

2018-02-01

Despite the promising results of the recent novel transcranial photoacoustic (PA) brain imaging technology, it has been demonstrated that the presence of the skull severely affects the performance of this imaging modality. We theoretically investigate the effects of acoustic heterogeneity induced by skull on the PA signals generated from single particles, with firstly developing a mathematical model for this phenomenon and then explore experimental validation of the results. The model takes into account the frequency dependent attenuation and dispersion effects occur with wave reflection, refraction and mode conversion at the skull surfaces. Numerical simulations based on the developed model are performed for calculating the propagation of photoacoustic waves through the skull. The results show a strong agreement between simulation and ex-vivo study. The findings are as follow: The thickness of the skull is the most PA signal deteriorating factor that affects both its amplitude (attenuation) and phase (distortion). Also we demonstrated that, when the depth of target region is low and it is comparable to the skull thickness, however, the skull-induced distortion becomes increasingly severe and the reconstructed image would be strongly distorted without correcting these effects. It is anticipated that an accurate quantification and modeling of the skull transmission effects would ultimately allow for aberration correction in transcranial PA brain imaging.

Aftershock Sequences and Seismic-Like Organization of Acoustic Events Produced by a Single Propagating Crack

NASA Astrophysics Data System (ADS)

Alizee, D.; Bonamy, D.

2017-12-01

In inhomogeneous brittle solids like rocks, concrete or ceramics, one usually distinguish nominally brittle fracture, driven by the propagation of a single crack from quasibrittle one, resulting from the accumulation of many microcracks. The latter goes along with intermittent sharp noise, as e.g. revealed by the acoustic emission observed in lab scale compressive fracture experiments or at geophysical scale in the seismic activity. In both cases, statistical analyses have revealed a complex time-energy organization into aftershock sequences obeying a range of robust empirical scaling laws (the Omori-Utsu, productivity and Bath's law) that help carry out seismic hazard analysis and damage mitigation. These laws are usually conjectured to emerge from the collective dynamics of microcrack nucleation. In the experiments presented at AGU, we will show that such a statistical organization is not specific to the quasi-brittle multicracking situations, but also rules the acoustic events produced by a single crack slowly driven in an artificial rock made of sintered polymer beads. This simpler situation has advantageous properties (statistical stationarity in particular) permitting us to uncover the origins of these seismic laws: Both productivity law and Bath's law result from the scale free statistics for event energy and Omori-Utsu law results from the scale-free statistics of inter-event time. This yields predictions on how the associated parameters are related, which were analytically derived. Surprisingly, the so-obtained relations are also compatible with observations on lab scale compressive fracture experiments, suggesting that, in these complex multicracking situations also, the organization into aftershock sequences and associated seismic laws are also ruled by the propagation of individual microcrack fronts, and not by the collective, stress-mediated, microcrack nucleation. Conversely, the relations are not fulfilled in seismology signals, suggesting that

ACOUSTIC LOCATION OF LEAKS IN PRESSURIZED UNDER- GROUND PETROLEUM PIPELINES

EPA Science Inventory

Experiments were conducted at the Underground Storage Tank (UST) Test Apparatus Pipeline in which three acoustic sensors separated by a maximum distance of 38.1 m (125 ft) were used to monitor signals produced by 11.4-, 5.7-, and 3.8-L/h (3.0-, 1.5-, and 1.0-gal/h) leaks in th...

Acoustic Signaling by Singing Humpback Whales (Megaptera novaeangliae): What Role Does Reverberation Play?

PubMed

Mercado, Eduardo

2016-01-01

When humpback whales (Megaptera novaeangliae) sing in coastal waters, the units they produce can generate reverberation. Traditionally, such reverberant acoustic energy has been viewed as an incidental side-effect of high-amplitude, long-distance, sound transmission in the ocean. An alternative possibility, however, is that reverberation actually contributes to the structure and function of songs. In the current study, this possibility was assessed by analyzing reverberation generated by humpback whale song units, as well as the spectral structure of unit sequences, produced by singers from different regions. Acoustical analyses revealed that: (1) a subset of units within songs generated narrowband reverberant energy that in some cases persisted for periods longer than the interval between units; (2) these highly reverberant units were regularly repeated throughout the production of songs; and (3) units occurring before and after these units often contained spectral energy peaks at non-overlapping, adjacent frequencies that were systematically related to the bands of reverberant energy generated by the units. These findings strongly suggest that some singing humpback whales not only produce sounds conducive to long-duration reverberation, but also may sequentially structure songs to avoid spectral overlap between units and ongoing reverberation. Singer-generated reverberant energy that is received simultaneously with directly transmitted song units can potentially provide listening whales with spatial cues that may enable them to more accurately determine a singer's position.

Acoustic Signaling by Singing Humpback Whales (Megaptera novaeangliae): What Role Does Reverberation Play?

PubMed Central

Mercado, Eduardo

2016-01-01

When humpback whales (Megaptera novaeangliae) sing in coastal waters, the units they produce can generate reverberation. Traditionally, such reverberant acoustic energy has been viewed as an incidental side-effect of high-amplitude, long-distance, sound transmission in the ocean. An alternative possibility, however, is that reverberation actually contributes to the structure and function of songs. In the current study, this possibility was assessed by analyzing reverberation generated by humpback whale song units, as well as the spectral structure of unit sequences, produced by singers from different regions. Acoustical analyses revealed that: (1) a subset of units within songs generated narrowband reverberant energy that in some cases persisted for periods longer than the interval between units; (2) these highly reverberant units were regularly repeated throughout the production of songs; and (3) units occurring before and after these units often contained spectral energy peaks at non-overlapping, adjacent frequencies that were systematically related to the bands of reverberant energy generated by the units. These findings strongly suggest that some singing humpback whales not only produce sounds conducive to long-duration reverberation, but also may sequentially structure songs to avoid spectral overlap between units and ongoing reverberation. Singer-generated reverberant energy that is received simultaneously with directly transmitted song units can potentially provide listening whales with spatial cues that may enable them to more accurately determine a singer’s position. PMID:27907182

How Do “Mute” Cicadas Produce Their Calling Songs?

PubMed Central

Luo, Changqing; Wei, Cong; Nansen, Christian

2015-01-01

Insects have evolved a variety of structures and mechanisms to produce sounds, which are used for communication both within and between species. Among acoustic insects, cicada males are particularly known for their loud and diverse sounds which function importantly in communication. The main method of sound production in cicadas is the tymbal mechanism, and a relative small number of cicada species possess both tymbal and stridulatory organs. However, cicadas of the genus Karenia do not have any specialized sound-producing structures, so they are referred to as “mute”. This denomination is quite misleading, as they indeed produce sounds. Here, we investigate the sound-producing mechanism and acoustic communication of the “mute” cicada, Karenia caelatata, and discover a new sound-production mechanism for cicadas: i.e., K. caelatata produces impact sounds by banging the forewing costa against the operculum. The temporal, frequency and amplitude characteristics of the impact sounds are described. Morphological studies and reflectance-based analyses reveal that the structures involved in sound production of K. caelatata (i.e., forewing, operculum, cruciform elevation, and wing-holding groove on scutellum) are all morphologically modified. Acoustic playback experiments and behavioral observations suggest that the impact sounds of K. caelatata are used in intraspecific communication and function as calling songs. The new sound-production mechanism expands our knowledge on the diversity of acoustic signaling behavior in cicadas and further underscores the need for more bioacoustic studies on cicadas which lack tymbal mechanism. PMID:25714608

Acoustic communication in insect disease vectors

PubMed Central

Vigoder, Felipe de Mello; Ritchie, Michael Gordon; Gibson, Gabriella; Peixoto, Alexandre Afranio

2013-01-01

Acoustic signalling has been extensively studied in insect species, which has led to a better understanding of sexual communication, sexual selection and modes of speciation. The significance of acoustic signals for a blood-sucking insect was first reported in the XIX century by Christopher Johnston, studying the hearing organs of mosquitoes, but has received relatively little attention in other disease vectors until recently. Acoustic signals are often associated with mating behaviour and sexual selection and changes in signalling can lead to rapid evolutionary divergence and may ultimately contribute to the process of speciation. Songs can also have implications for the success of novel methods of disease control such as determining the mating competitiveness of modified insects used for mass-release control programs. Species-specific sound “signatures” may help identify incipient species within species complexes that may be of epidemiological significance, e.g. of higher vectorial capacity, thereby enabling the application of more focussed control measures to optimise the reduction of pathogen transmission. Although the study of acoustic communication in insect vectors has been relatively limited, this review of research demonstrates their value as models for understanding both the functional and evolutionary significance of acoustic communication in insects. PMID:24473800

Evidence for acoustic communication among bottom foraging humpback whales

PubMed Central

Parks, Susan E.; Cusano, Dana A.; Stimpert, Alison K.; Weinrich, Mason T.; Friedlaender, Ari S.; Wiley, David N.

2014-01-01

Humpback whales (Megaptera novaeangliae), a mysticete with a cosmopolitan distribution, demonstrate marked behavioural plasticity. Recent studies show evidence of social learning in the transmission of specific population level traits ranging from complex singing to stereotyped prey capturing behaviour. Humpback whales have been observed to employ group foraging techniques, however details on how individuals coordinate behaviour in these groups is challenging to obtain. This study investigates the role of a novel broadband patterned pulsed sound produced by humpback whales engaged in bottom-feeding behaviours, referred to here as a ‘paired burst' sound. Data collected from 56 archival acoustic tag deployments were investigated to determine the functional significance of these signals. Paired burst sound production was associated exclusively with bottom feeding under low-light conditions, predominantly with evidence of associated conspecifics nearby suggesting that the sound likely serves either as a communicative signal to conspecifics, a signal to affect prey behaviour, or possibly both. This study provides additional evidence for individual variation and phenotypic plasticity of foraging behaviours in humpback whales and provides important evidence for the use of acoustic signals among foraging individuals in this species. PMID:25512188

Evidence for acoustic communication among bottom foraging humpback whales.

PubMed

Parks, Susan E; Cusano, Dana A; Stimpert, Alison K; Weinrich, Mason T; Friedlaender, Ari S; Wiley, David N

2014-12-16

Humpback whales (Megaptera novaeangliae), a mysticete with a cosmopolitan distribution, demonstrate marked behavioural plasticity. Recent studies show evidence of social learning in the transmission of specific population level traits ranging from complex singing to stereotyped prey capturing behaviour. Humpback whales have been observed to employ group foraging techniques, however details on how individuals coordinate behaviour in these groups is challenging to obtain. This study investigates the role of a novel broadband patterned pulsed sound produced by humpback whales engaged in bottom-feeding behaviours, referred to here as a 'paired burst' sound. Data collected from 56 archival acoustic tag deployments were investigated to determine the functional significance of these signals. Paired burst sound production was associated exclusively with bottom feeding under low-light conditions, predominantly with evidence of associated conspecifics nearby suggesting that the sound likely serves either as a communicative signal to conspecifics, a signal to affect prey behaviour, or possibly both. This study provides additional evidence for individual variation and phenotypic plasticity of foraging behaviours in humpback whales and provides important evidence for the use of acoustic signals among foraging individuals in this species.

Air-coupled acoustic thermography for in-situ evaluation

NASA Technical Reports Server (NTRS)

Zalameda, Joseph N. (Inventor); Winfree, William P. (Inventor); Yost, William T. (Inventor)

2010-01-01

Acoustic thermography uses a housing configured for thermal, acoustic and infrared radiation shielding. For in-situ applications, the housing has an open side adapted to be sealingly coupled to a surface region of a structure such that an enclosed chamber filled with air is defined. One or more acoustic sources are positioned to direct acoustic waves through the air in the enclosed chamber and towards the surface region. To activate and control each acoustic source, a pulsed signal is applied thereto. An infrared imager focused on the surface region detects a thermal image of the surface region. A data capture device records the thermal image in synchronicity with each pulse of the pulsed signal such that a time series of thermal images is generated. For enhanced sensitivity and/or repeatability, sound and/or vibrations at the surface region can be used in feedback control of the pulsed signal applied to the acoustic sources.

Modeling skull's acoustic attenuation and dispersion on photoacoustic signal

NASA Astrophysics Data System (ADS)

Mohammadi, L.; Behnam, H.; Nasiriavanaki, M. R.

2017-03-01

Despite the great promising results of a recent new transcranial photoacoustic brain imaging technology, it has been shown that the presence of the skull severely affects the performance of this imaging modality. In this paper, we investigate the effect of skull on generated photoacoustic signals with a mathematical model. The developed model takes into account the frequency dependence attenuation and acoustic dispersion effects occur with the wave reflection and refraction at the skull surface. Numerical simulations based on the developed model are performed for calculating the propagation of photoacoustic waves through the skull. From the simulation results, it was found that the skull-induced distortion becomes very important and the reconstructed image would be strongly distorted without correcting these effects. In this regard, it is anticipated that an accurate quantification and modeling of the skull transmission effects would ultimately allow for skull aberration correction in transcranial photoacoustic brain imaging.

Bondable Fluoropolymer Film as a Water Block/Acoustic Window for Environmentally Isolating Acoustic Devices

DTIC Science & Technology

2005-11-30

titanium 2 I foil which is wrapped around a polyurethane molded acoustic 2 device and local preamplifier for the purpose of water-proofing 3 and...typical sonar signals transmitted through the 14 films 12 and 14. Therefore, the film 12 can be added to 15 traditional acoustic window designs to...4 virtually no effect on typical sonar signals yet eliminates an 5 otherwise costly and relatively thick rubber or polymer skin that 6 can be

A Modified Empirical Wavelet Transform for Acoustic Emission Signal Decomposition in Structural Health Monitoring.

PubMed

Dong, Shaopeng; Yuan, Mei; Wang, Qiusheng; Liang, Zhiling

2018-05-21

The acoustic emission (AE) method is useful for structural health monitoring (SHM) of composite structures due to its high sensitivity and real-time capability. The main challenge, however, is how to classify the AE data into different failure mechanisms because the detected signals are affected by various factors. Empirical wavelet transform (EWT) is a solution for analyzing the multi-component signals and has been used to process the AE data. In order to solve the spectrum separation problem of the AE signals, this paper proposes a novel modified separation method based on local window maxima (LWM) algorithm. It searches the local maxima of the Fourier spectrum in a proper window, and automatically determines the boundaries of spectrum segmentations, which helps to eliminate the impact of noise interference or frequency dispersion in the detected signal and obtain the meaningful empirical modes that are more related to the damage characteristics. Additionally, both simulation signal and AE signal from the composite structures are used to verify the effectiveness of the proposed method. Finally, the experimental results indicate that the proposed method performs better than the original EWT method in identifying different damage mechanisms of composite structures.

A Modified Empirical Wavelet Transform for Acoustic Emission Signal Decomposition in Structural Health Monitoring

PubMed Central

Dong, Shaopeng; Yuan, Mei; Wang, Qiusheng; Liang, Zhiling

2018-01-01

The acoustic emission (AE) method is useful for structural health monitoring (SHM) of composite structures due to its high sensitivity and real-time capability. The main challenge, however, is how to classify the AE data into different failure mechanisms because the detected signals are affected by various factors. Empirical wavelet transform (EWT) is a solution for analyzing the multi-component signals and has been used to process the AE data. In order to solve the spectrum separation problem of the AE signals, this paper proposes a novel modified separation method based on local window maxima (LWM) algorithm. It searches the local maxima of the Fourier spectrum in a proper window, and automatically determines the boundaries of spectrum segmentations, which helps to eliminate the impact of noise interference or frequency dispersion in the detected signal and obtain the meaningful empirical modes that are more related to the damage characteristics. Additionally, both simulation signal and AE signal from the composite structures are used to verify the effectiveness of the proposed method. Finally, the experimental results indicate that the proposed method performs better than the original EWT method in identifying different damage mechanisms of composite structures. PMID:29883411

Computation of acoustic ressure fields produced in feline brain by high-intensity focused ultrasound

NASA Astrophysics Data System (ADS)

Omidi, Nazanin

In 1975, Dunn et al. (JASA 58:512-514) showed that a simple relation describes the ultrasonic threshold for cavitation-induced changes in the mammalian brain. The thresholds for tissue damage were estimated for a variety of acoustic parameters in exposed feline brain. The goal of this study was to improve the estimates for acoustic pressures and intensities present in vivo during those experimental exposures by estimating them using nonlinear rather than linear theory. In our current project, the acoustic pressure waveforms produced in the brains of anesthetized felines were numerically simulated for a spherically focused, nominally f1-transducer (focal length = 13 cm) at increasing values of the source pressure at frequencies of 1, 3, and 9 MHz. The corresponding focal intensities were correlated with the experimental data of Dunn et al. The focal pressure waveforms were also computed at the location of the true maximum. For low source pressures, the computed waveforms were the same as those determined using linear theory, and the focal intensities matched experimentally determined values. For higher source pressures, the focal pressure waveforms became increasingly distorted, with the compressional amplitude of the wave becoming greater, and the rarefactional amplitude becoming lower than the values calculated using linear theory. The implications of these results for clinical exposures are discussed.

Discrimination of acoustically similar conspecific and heterospecific vocalizations by black-capped chickadees (Poecile atricapillus).

PubMed

Hahn, Allison H; Campbell, Kimberley A; Congdon, Jenna V; Hoang, John; McMillan, Neil; Scully, Erin N; Yong, Joshua J H; Elie, Julie E; Sturdy, Christopher B

2017-07-01

Chickadees produce a multi-note chick-a-dee call in multiple socially relevant contexts. One component of this call is the D note, which is a low-frequency and acoustically complex note with a harmonic-like structure. In the current study, we tested black-capped chickadees on a between-category operant discrimination task using vocalizations with acoustic structures similar to black-capped chickadee D notes, but produced by various songbird species, in order to examine the role that phylogenetic distance plays in acoustic perception of vocal signals. We assessed the extent to which discrimination performance was influenced by the phylogenetic relatedness among the species producing the vocalizations and by the phylogenetic relatedness between the subjects' species (black-capped chickadees) and the vocalizers' species. We also conducted a bioacoustic analysis and discriminant function analysis in order to examine the acoustic similarities among the discrimination stimuli. A previous study has shown that neural activation in black-capped chickadee auditory and perceptual brain regions is similar following the presentation of these vocalization categories. However, we found that chickadees had difficulty discriminating between forward and reversed black-capped chickadee D notes, a result that directly corresponded to the bioacoustic analysis indicating that these stimulus categories were acoustically similar. In addition, our results suggest that the discrimination between vocalizations produced by two parid species (chestnut-backed chickadees and tufted titmice) is perceptually difficult for black-capped chickadees, a finding that is likely in part because these vocalizations contain acoustic similarities. Overall, our results provide evidence that black-capped chickadees' perceptual abilities are influenced by both phylogenetic relatedness and acoustic structure.

Detection of Delamination in Concrete Bridge Decks Using Mfcc of Acoustic Impact Signals

NASA Astrophysics Data System (ADS)

Zhang, G.; Harichandran, R. S.; Ramuhalli, P.

2010-02-01

Delamination of the concrete cover is a commonly observed damage in concrete bridge decks. The delamination is typically initiated by corrosion of the upper reinforcing bars and promoted by freeze-thaw cycling and traffic loading. The detection of delamination is important for bridge maintenance and acoustic non-destructive evaluation (NDE) is widely used due to its low cost, speed, and easy implementation. In traditional acoustic approaches, the inspector sounds the surface of the deck by impacting it with a hammer or bar, or by dragging a chain, and assesses delamination by the "hollowness" of the sound. The detection of the delamination is subjective and requires extensive training. To improve performance, this paper proposes an objective method for delamination detection. In this method, mel-frequency cepstral coefficients (MFCC) of the signal are extracted. Some MFCC are then selected as features for detection purposes using a mutual information criterion. Finally, the selected features are used to train a classifier which is subsequently used for detection. In this work, a simple quadratic Bayesian classifier is used. Different numbers of features are used to compare the performance of the detection method. The results show that the performance first increases with the number of features, but then decreases after an optimal value. The optimal number of features based on the recorded signals is four, and the mean error rate is only 3.3% when four features are used. Therefore, the proposed algorithm has sufficient accuracy to be used in field detection.

Acoustic Levitation With Less Equipment

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Jacobi, N.

1983-01-01

Certain chamber shapes require fewer than three acoustic drivers. Levitation at center of spherical chamber attained using only one acoustic driver. Exitation of lowest spherical mode produces asymmetric acoustic potential well.

Wideband acoustic microscopy of tissue.

PubMed

Daft, C W; Briggs, G D

1989-01-01

A scanning acoustic microscope (SAM) has been used to measure the elastic properties of tissue with a resolution of around 8 mum. This is achieved by broadband excitation of the acoustic lens, and the recording of an undemodulated returning signal. A method of analyzing this information to yield sound velocity, acoustic impedance, section thickness, and acoustic attenuation is described. Results from a sample of skin tissue are presented and compared with data from a computer simulation of the experiment.

Seismo-acoustic analysis of the near quarry blasts using Plostina small aperture array

NASA Astrophysics Data System (ADS)

Ghica, Daniela; Stancu, Iulian; Ionescu, Constantin

2013-04-01

Seismic and acoustic signals are important to recognize different type of industrial blasting sources in order to discriminate between them and natural earthquakes. We have analyzed the seismic events listed in the Romanian catalogue (Romplus) for the time interval between 2011 and 2012, and occurred in the Dobrogea region, in order to determine detection seismo-acoustic signals of quarry blasts by Plostina array stations. Dobrogea is known as a seismic region characterized by crustal earthquakes with low magnitudes; at the same time, over 40 quarry mines are located in the area, being sources of blasts recorded both with the seismic and infrasound sensors of the Romanian Seismic Network. Plostina seismo-acoustic array, deployed in the central part of Romania, consists of 7 seismic sites (3C broad-band instruments and accelerometers) collocated with 7 infrasound instruments. The array is particularly used for the seismic monitoring of the local and regional events, as well as for the detection of infrasonic signals produced by various sources. Considering the characteristics of the infrasound sensors (frequency range, dynamic, sensibility), the array proved its efficiency in observing the signals produced by explosions, mine explosion and quarry blasts. The quarry mines included for this study cover distances of two hundreds of kilometers from the station and routinely generate explosions that are detected as seismic and infrasonic signals with Plostina array. The combined seismo-acoustic analysis uses two types of detectors for signal identification: one, applied for the seismic signal identification, is based on array processing techniques (beamforming and frequency-wave number analysis), while the other one, which is used for infrasound detection and characterization, is the automatic detector DFX-PMCC (Progressive Multi-Channel Correlation Method). Infrasonic waves generated by quarry blasts have frequencies ranging from 0.05 Hz up to at least 6 Hz and

Sound production in the tiger-tail seahorse Hippocampus comes: Insights into the sound producing mechanisms.

PubMed

Lim, A C O; Chong, V C; Chew, W X; Muniandy, S V; Wong, C S; Ong, Z C

2015-07-01

Acoustic signals of the tiger-tail seahorse (Hippocampus comes) during feeding were studied using wavelet transform analysis. The seahorse "click" appears to be a compounded sound, comprising three acoustic components that likely come from two sound producing mechanisms. The click sound begins with a low-frequency precursor signal, followed by a sudden high-frequency spike that decays quickly, and a final, low-frequency sinusoidal component. The first two components can, respectively, be traced to the sliding movement and forceful knock between the supraorbital bone and coronet bone of the cranium, while the third one (purr) although appearing to be initiated here is produced elsewhere. The seahorse also produces a growling sound when under duress. Growling is accompanied by the highest recorded vibration at the cheek indicating another sound producing mechanism here. The purr has the same low frequency as the growl; both are likely produced by the same structural mechanism. However, growl and purr are triggered and produced under different conditions, suggesting that such "vocalization" may have significance in communication between seahorses.

Development of Microbubble Contrast Agents with Biochemical Recognition and Tunable Acoustic Response

NASA Astrophysics Data System (ADS)

Nakatsuka, Matthew Allan Masao

Microbubbles, consisting of gas-filled cores encapsulated within phospholipid or polymer shells, are the most widely used ultrasound contrast agents in the world. Because of their acoustic impedance mismatch with surrounding tissues and compressible gaseous interiors, they have high echogenicities that allow for efficient backscatter of ultrasound. They can also generate unique harmonic frequencies when insonated near their resonance frequency, depending on physical microbubble properties such as the stiffness and thickness of the encapsulating shell. Microbubbles are used to detect a number of cardiovascular diseases, but current methodologies lack the ability to detect and distinguish small, rapidly growing abnormalities that do not produce visible blockage or slowing of blood flow. This work describes the development, formulation, and validation of microbubbles with various polymer shell architectures designed to modulate their acoustic ability. We demonstrate that the addition of a thick disulfide crosslinked, poly(acrylic acid) encapsulating shell increases a bubble's resistance to cavitation and changes its resonance frequency. Modification of this shell architecture to use hybridized DNA strands to form crosslinks between the polymer chains allows for tuning of the bubble acoustic response. When the DNA crosslinks are in place, shell stiffness is increased so the bubbles do not oscillate and acoustic signal is muted. Subsequently, when these DNA strands are displaced, partial acoustic activity is restored. By using aptamer sequences with a specific affinity towards the biomolecule thrombin as the DNA crosslinking strand, this acoustic "ON/OFF" behavior can be specifically tailored towards the presence of a specific biomarker, and produces a change in acoustic signal at concentrations of thrombin consistent with acute deep venous thrombosis. Incorporation of the emulsifying agent poly(ethylene glycol) into the encapsulating shell improves microbubble yield

A hydrophone prototype for ultra high energy neutrino acoustic detection

NASA Astrophysics Data System (ADS)

Cotrufo, A.; Plotnikov, A.; Yershova, O.; Anghinolfi, M.; Piombo, D.

2009-06-01

The design of an air-backed fiber-optic hydrophone is presented. With respect to the previous models this prototype is optimized to provide a bandwidth sufficiently large to detect acoustic signals produced by high energy hadronic showers in water. In addiction to the geometrical configuration and to the choice of the materials, the preliminary results of the measured performances in air are presented.

Characterization of space dust using acoustic impact detection.

PubMed

Corsaro, Robert D; Giovane, Frank; Liou, Jer-Chyi; Burchell, Mark J; Cole, Michael J; Williams, Earl G; Lagakos, Nicholas; Sadilek, Albert; Anderson, Christopher R

2016-08-01

This paper describes studies leading to the development of an acoustic instrument for measuring properties of micrometeoroids and other dust particles in space. The instrument uses a pair of easily penetrated membranes separated by a known distance. Sensors located on these films detect the transient acoustic signals produced by particle impacts. The arrival times of these signals at the sensor locations are used in a simple multilateration calculation to measure the impact coordinates on each film. Particle direction and speed are found using these impact coordinates and the known membrane separations. This ability to determine particle speed, direction, and time of impact provides the information needed to assign the particle's orbit and identify its likely origin. In many cases additional particle properties can be estimated from the signal amplitudes, including approximate diameter and (for small particles) some indication of composition/morphology. Two versions of this instrument were evaluated in this study. Fiber optic displacement sensors are found advantageous when very thin membranes can be maintained in tension (solar sails, lunar surface). Piezoelectric strain sensors are preferred for thicker films without tension (long duration free flyers). The latter was selected for an upcoming installation on the International Space Station.

F-16XL and F-18 High Speed Acoustic Flight Test Databases

NASA Technical Reports Server (NTRS)

Kelly, J. J.; Wilson, M. R.; Rawls, J., Jr.; Norum, T. D.; Golub, R. A.

1999-01-01

This report presents the recorded acoustic data and the computed narrow-band and 1/3-octave band spectra produced by F-18 and F-16XL aircraft in subsonic flight over an acoustic array. Both broadband-shock noise and turbulent mixing noise are observed in the spectra. Radar and c-band tracking systems provided the aircraft position which enabled directivity and smear angles from the aircraft to each microphone to be computed. These angles are based on source emission time and thus give some idea about the directivity of the radiated sound field due to jet noise. A follow-on static test was also conducted where acoustic and engine data were obtained. The acoustic data described in the report has application to community noise analysis, noise source characterization and validation of prediction models. A detailed description of the signal processing procedures is provided. Follow-on static tests of each aircraft were also conducted for which engine data and far-field acoustic data are presented.

Magneto acoustic emission apparatus for testing materials for embrittlement

NASA Technical Reports Server (NTRS)

Allison, Sidney G. (Inventor); Min, Namkung (Inventor); Yost, William T. (Inventor); Cantrell, John H. (Inventor)

1990-01-01

A method and apparatus for testing steel components for temper embrittlement uses magneto-acoustic emission to nondestructively evaluate the component. Acoustic emission signals occur more frequently at higher levels in embrittled components. A pair of electromagnets are used to create magnetic induction in the test component. Magneto-acoustic emission signals may be generated by applying an ac current to the electromagnets. The acoustic emission signals are analyzed to provide a comparison between a component known to be unembrittled and a test component. Magnetic remanence is determined by applying a dc current to the electromagnets, then turning the magnets off and observing the residual magnetic induction.

Quantifying activation of perfluorocarbon-based phase-change contrast agents using simultaneous acoustic and optical observation.

PubMed

Li, Sinan; Lin, Shengtao; Cheng, Yi; Matsunaga, Terry O; Eckersley, Robert J; Tang, Meng-Xing

2015-05-01

Phase-change contrast agents in the form of nanoscale droplets can be activated into microbubbles by ultrasound, extending the contrast beyond the vasculature. This article describes simultaneous optical and acoustical measurements for quantifying the ultrasound activation of phase-change contrast agents over a range of concentrations. In experiments, decafluorobutane-based nanodroplets of different dilutions were sonicated with a high-pressure activation pulse and two low-pressure interrogation pulses immediately before and after the activation pulse. The differences between the pre- and post-interrogation signals were calculated to quantify the acoustic power scattered by the microbubbles activated over a range of droplet concentrations. Optical observation occurred simultaneously with the acoustic measurement, and the pre- and post-microscopy images were processed to generate an independent quantitative indicator of the activated microbubble concentration. Both optical and acoustic measurements revealed linear relationships to the droplet concentration at a low concentration range <10(8)/mL when measured at body temperature. Further increases in droplet concentration resulted in saturation of the acoustic interrogation signal. Compared with body temperature, room temperature was found to produce much fewer and larger bubbles after ultrasound droplet activation. Copyright © 2015. Published by Elsevier Inc.

Acoustic signal propagation and measurement in natural stream channels for application to surrogate bed load measurements: Halfmoon Creek, Colorado

USDA-ARS?s Scientific Manuscript database

Monitoring sediment-generated noise using submerged hydrophones is a surrogate method for measuring bed load transport in streams with the potential for improving estimates of bed load transport through widespread, inexpensive monitoring. Understanding acoustic signal propagation in natural stream e...

Acoustic velocity meter systems

USGS Publications Warehouse

Laenen, Antonius

1985-01-01

Acoustic velocity meter (AVM) systems operate on the principles that the point-to-point upstream traveltime of an acoustic pulse is longer than the downstream traveltime and that this difference in traveltime can be accurately measured by electronic devices. An AVM system is capable of recording water velocity (and discharge) under a wide range of conditions, but some constraints apply: 1. Accuracy is reduced and performance is degraded if the acoustic path is not a continuous straight line. The path can be bent by reflection if it is too close to a stream boundary or by refraction if it passes through density gradients resulting from variations in either water temperature or salinity. For paths of less than 100 m, a temperature gradient of 0.1' per meter causes signal bending less than 0.6 meter at midchannel, and satisfactory velocity results can be obtained. Reflection from stream boundaries can cause signal cancellation if boundaries are too close to signal path. 2. Signal strength is attenuated by particles or bubbles that absorb, spread, or scatter sound. The concentration of particles or bubbles that can be tolerated is a function of the path length and frequency of the acoustic signal. 3. Changes in streamline orientation can affect system accuracy if the variability is random. 4. Errors relating to signal resolution are much larger for a single threshold detection scheme than for multiple threshold schemes. This report provides methods for computing the effect of various conditions on the accuracy of a record obtained from an AVM. The equipment must be adapted to the site. Field reconnaissance and preinstallation analysis to detect possible problems are critical for proper installation and operation of an AVM system.

New early warning system for gravity-driven ruptures based on codetection of acoustic signal

NASA Astrophysics Data System (ADS)

Faillettaz, J.

2016-12-01

Gravity-driven rupture phenomena in natural media - e.g. landslide, rockfalls, snow or ice avalanches - represent an important class of natural hazards in mountainous regions. To protect the population against such events, a timely evacuation often constitutes the only effective way to secure the potentially endangered area. However, reliable prediction of imminence of such failure events remains challenging due to the nonlinear and complex nature of geological material failure hampered by inherent heterogeneity, unknown initial mechanical state, and complex load application (rainfall, temperature, etc.). Here, a simple method for real-time early warning that considers both the heterogeneity of natural media and characteristics of acoustic emissions attenuation is proposed. This new method capitalizes on codetection of elastic waves emanating from microcracks by multiple and spatially separated sensors. Event-codetection is considered as surrogate for large event size with more frequent codetected events (i.e., detected concurrently on more than one sensor) marking imminence of catastrophic failure. Simple numerical model based on a Fiber Bundle Model considering signal attenuation and hypothetical arrays of sensors confirms the early warning potential of codetection principles. Results suggest that although statistical properties of attenuated signal amplitude could lead to misleading results, monitoring the emergence of large events announcing impeding failure is possible even with attenuated signals depending on sensor network geometry and detection threshold. Preliminary application of the proposed method to acoustic emissions during failure of snow samples has confirmed the potential use of codetection as indicator for imminent failure at lab scale. The applicability of such simple and cheap early warning system is now investigated at a larger scale (hillslope). First results of such a pilot field experiment are presented and analysed.

Auditory object salience: human cortical processing of non-biological action sounds and their acoustic signal attributes

PubMed Central

Lewis, James W.; Talkington, William J.; Tallaksen, Katherine C.; Frum, Chris A.

2012-01-01

Whether viewed or heard, an object in action can be segmented as a distinct salient event based on a number of different sensory cues. In the visual system, several low-level attributes of an image are processed along parallel hierarchies, involving intermediate stages wherein gross-level object form and/or motion features are extracted prior to stages that show greater specificity for different object categories (e.g., people, buildings, or tools). In the auditory system, though relying on a rather different set of low-level signal attributes, meaningful real-world acoustic events and “auditory objects” can also be readily distinguished from background scenes. However, the nature of the acoustic signal attributes or gross-level perceptual features that may be explicitly processed along intermediate cortical processing stages remain poorly understood. Examining mechanical and environmental action sounds, representing two distinct non-biological categories of action sources, we had participants assess the degree to which each sound was perceived as object-like versus scene-like. We re-analyzed data from two of our earlier functional magnetic resonance imaging (fMRI) task paradigms (Engel et al., 2009) and found that scene-like action sounds preferentially led to activation along several midline cortical structures, but with strong dependence on listening task demands. In contrast, bilateral foci along the superior temporal gyri (STG) showed parametrically increasing activation to action sounds rated as more “object-like,” independent of sound category or task demands. Moreover, these STG regions also showed parametric sensitivity to spectral structure variations (SSVs) of the action sounds—a quantitative measure of change in entropy of the acoustic signals over time—and the right STG additionally showed parametric sensitivity to measures of mean entropy and harmonic content of the environmental sounds. Analogous to the visual system, intermediate stages

Novel Fiber-Optic Ring Acoustic Emission Sensor.

PubMed

Wei, Peng; Han, Xiaole; Xia, Dong; Liu, Taolin; Lang, Hao

2018-01-13

Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments.

Velocity measurement by vibro-acoustic Doppler.

PubMed

Nabavizadeh, Alireza; Urban, Matthew W; Kinnick, Randall R; Fatemi, Mostafa

2012-04-01

We describe the theoretical principles of a new Doppler method, which uses the acoustic response of a moving object to a highly localized dynamic radiation force of the ultrasound field to calculate the velocity of the moving object according to Doppler frequency shift. This method, named vibro-acoustic Doppler (VAD), employs two ultrasound beams separated by a slight frequency difference, Δf, transmitting in an X-focal configuration. Both ultrasound beams experience a frequency shift because of the moving objects and their interaction at the joint focal zone produces an acoustic frequency shift occurring around the low-frequency (Δf) acoustic emission signal. The acoustic emission field resulting from the vibration of the moving object is detected and used to calculate its velocity. We report the formula that describes the relation between Doppler frequency shift of the emitted acoustic field and the velocity of the moving object. To verify the theory, we used a string phantom. We also tested our method by measuring fluid velocity in a tube. The results show that the error calculated for both string and fluid velocities is less than 9.1%. Our theory shows that in the worst case, the error is 0.54% for a 25° angle variation for the VAD method compared with an error of -82.6% for a 25° angle variation for a conventional continuous wave Doppler method. An advantage of this method is that, unlike conventional Doppler, it is not sensitive to angles between the ultrasound beams and direction of motion.

'Megapclicks': acoustic click trains and buzzes produced during night-time foraging of humpback whales (Megaptera novaeangliae).

PubMed

Stimpert, Alison K; Wiley, David N; Au, Whitlow W L; Johnson, Mark P; Arsenault, Roland

2007-10-22

Humpback whales (Megaptera novaeangliae) exhibit a variety of foraging behaviours, but neither they nor any baleen whale are known to produce broadband clicks in association with feeding, as do many odontocetes. We recorded underwater behaviour of humpback whales in a northwest Atlantic feeding area using suction-cup attached, multi-sensor, acoustic tags (DTAGs). Here we describe the first recordings of click production associated with underwater lunges from baleen whales. Recordings of over 34000 'megapclicks' from two whales indicated relatively low received levels at the tag (between 143 and 154dB re 1 microPa pp), most energy below 2kHz, and interclick intervals often decreasing towards the end of click trains to form a buzz. All clicks were recorded during night-time hours. Sharp body rolls also occurred at the end of click bouts containing buzzes, suggesting feeding events. This acoustic behaviour seems to form part of a night-time feeding tactic for humpbacks and also expands the known acoustic repertoire of baleen whales in general.

System for generating a beam of acoustic energy from a borehole, and applications thereof

DOEpatents

Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher

2012-09-04

In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

System for generating a beam of acoustic energy from a borehole, and applications thereof

DOEpatents

Vu, Cung Khac [Houston, TX; Sinha, Dipen N [Los Alamos, NM; Pantea, Cristian [Los Alamos, NM; Nihei, Kurt T [Oakland, CA; Schmitt, Denis P [Katy, TX; Skelt, Christopher [Houston, TX

2012-07-31

In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

An experimental device for characterizing degassing processes and related elastic fingerprints: Analog volcano seismo-acoustic observations.

PubMed

Spina, Laura; Morgavi, Daniele; Cannata, Andrea; Campeggi, Carlo; Perugini, Diego

2018-05-01

A challenging objective of modern volcanology is to quantitatively characterize eruptive/degassing regimes from geophysical signals (in particular seismic and infrasonic), for both research and monitoring purposes. However, the outcomes of the attempts made so far are still considered very uncertain because volcanoes remain inaccessible when deriving quantitative information on crucial parameters such as plumbing system geometry and magma viscosity. In order to improve our knowledge of volcanic systems, a novel experimental device, which is capable of mimicking volcanic degassing processes with different regimes and gas flow rates, and allowing for the investigation of the related seismo-acoustic emissions, was designed and developed. The benefits of integrating observations on real volcanoes with seismo-acoustic signals generated in laboratory are many and include (i) the possibility to fix the controlling parameters such as the geometry of the structure where the gas flows, the gas flow rate, and the fluid viscosity; (ii) the possibility of performing acoustic measurements at different azimuthal and zenithal angles around the opening of the analog conduit, hence constraining the radiation pattern of different acoustic sources; (iii) the possibility to measure micro-seismic signals in distinct points of the analog conduit; (iv) finally, thanks to the transparent structure, it is possible to directly observe the degassing pattern through the optically clear analog magma and define the degassing regime producing the seismo-acoustic radiations. The above-described device represents a step forward in the analog volcano seismo-acoustic measurements.

An experimental device for characterizing degassing processes and related elastic fingerprints: Analog volcano seismo-acoustic observations

NASA Astrophysics Data System (ADS)

Spina, Laura; Morgavi, Daniele; Cannata, Andrea; Campeggi, Carlo; Perugini, Diego

2018-05-01

A challenging objective of modern volcanology is to quantitatively characterize eruptive/degassing regimes from geophysical signals (in particular seismic and infrasonic), for both research and monitoring purposes. However, the outcomes of the attempts made so far are still considered very uncertain because volcanoes remain inaccessible when deriving quantitative information on crucial parameters such as plumbing system geometry and magma viscosity. In order to improve our knowledge of volcanic systems, a novel experimental device, which is capable of mimicking volcanic degassing processes with different regimes and gas flow rates, and allowing for the investigation of the related seismo-acoustic emissions, was designed and developed. The benefits of integrating observations on real volcanoes with seismo-acoustic signals generated in laboratory are many and include (i) the possibility to fix the controlling parameters such as the geometry of the structure where the gas flows, the gas flow rate, and the fluid viscosity; (ii) the possibility of performing acoustic measurements at different azimuthal and zenithal angles around the opening of the analog conduit, hence constraining the radiation pattern of different acoustic sources; (iii) the possibility to measure micro-seismic signals in distinct points of the analog conduit; (iv) finally, thanks to the transparent structure, it is possible to directly observe the degassing pattern through the optically clear analog magma and define the degassing regime producing the seismo-acoustic radiations. The above-described device represents a step forward in the analog volcano seismo-acoustic measurements.

Study of acoustic correlates associate with emotional speech

NASA Astrophysics Data System (ADS)

Yildirim, Serdar; Lee, Sungbok; Lee, Chul Min; Bulut, Murtaza; Busso, Carlos; Kazemzadeh, Ebrahim; Narayanan, Shrikanth

2004-10-01

This study investigates the acoustic characteristics of four different emotions expressed in speech. The aim is to obtain detailed acoustic knowledge on how a speech signal is modulated by changes from neutral to a certain emotional state. Such knowledge is necessary for automatic emotion recognition and classification and emotional speech synthesis. Speech data obtained from two semi-professional actresses are analyzed and compared. Each subject produces 211 sentences with four different emotions; neutral, sad, angry, happy. We analyze changes in temporal and acoustic parameters such as magnitude and variability of segmental duration, fundamental frequency and the first three formant frequencies as a function of emotion. Acoustic differences among the emotions are also explored with mutual information computation, multidimensional scaling and acoustic likelihood comparison with normal speech. Results indicate that speech associated with anger and happiness is characterized by longer duration, shorter interword silence, higher pitch and rms energy with wider ranges. Sadness is distinguished from other emotions by lower rms energy and longer interword silence. Interestingly, the difference in formant pattern between [happiness/anger] and [neutral/sadness] are better reflected in back vowels such as /a/(/father/) than in front vowels. Detailed results on intra- and interspeaker variability will be reported.

An Investigation of Acoustic Wave Propagation in Mach 2 Flow

NASA Astrophysics Data System (ADS)

Nieberding, Zachary J.

Hypersonic technology is the next advancement to enter the aerospace community; it is defined as the study of flight at speeds Mach 5 and higher where intense aerodynamic heating is prevalent. Hypersonic flight is achieved through use of scramjet engines, which intake air and compress it by means of shock waves and geometry design. The airflow is then directed through an isolator where it is further compressed, it is then delivered to the combustor at supersonic speeds. The combusted airflow and fuel mixture is then accelerated through a nozzle to achieve the hypersonic speeds. Unfortunately, scramjet engines can experience a phenomenon known as an inlet unstart, where the combustor produces pressures large enough to force the incoming airflow out of the inlet of the engine, resulting in a loss of acceleration and power. There have been several government-funded programs that look to prove the concept of the scramjet engine and also tackle this inlet unstart issue. The research conducted in this thesis is a fundamental approach towards controlling the unstart problem: it looks at the basic concept of sending a signal upstream through the boundary layer of a supersonic flow and being able to detect a characterizeable signal. Since conditions within and near the combustor are very harsh, hardware is unable to be installed in that area, so this testing will determine if a signal can be sent and if so, how far upstream can the signal be detected. This experimental approach utilizes several acoustic and mass injection sources to be evaluated over three test series in a Mach 2 continuous flow wind tunnel that will determine the success of the objective. The test series vary in that the conditions of the flow and the test objectives change. The research shows that a characterizeable signal can be transmitted upstream roughly 12 inches through the subsonic boundary layer of a supersonic cross flow. It is also shown that the signal attenuates as the distance between the

Acoustic constituents of prosodic typology

NASA Astrophysics Data System (ADS)

Komatsu, Masahiko

Different languages sound different, and considerable part of it derives from the typological difference of prosody. Although such difference is often referred to as lexical accent types (stress accent, pitch accent, and tone; e.g. English, Japanese, and Chinese respectively) and rhythm types (stress-, syllable-, and mora-timed rhythms; e.g. English, Spanish, and Japanese respectively), it is unclear whether these types are determined in terms of acoustic properties, The thesis intends to provide a potential basis for the description of prosody in terms of acoustics. It argues for the hypothesis that the source component of the source-filter model (acoustic features) approximately corresponds to prosody (linguistic features) through several experimental-phonetic studies. The study consists of four parts. (1) Preliminary experiment: Perceptual language identification tests were performed using English and Japanese speech samples whose frequency spectral information (i.e. non-source component) is heavily reduced. The results indicated that humans can discriminate languages with such signals. (2) Discussion on the linguistic information that the source component contains: This part constitutes the foundation of the argument of the thesis. Perception tests of consonants with the source signal indicated that the source component carries the information on broad categories of phonemes that contributes to the creation of rhythm. (3) Acoustic analysis: The speech samples of Chinese, English, Japanese, and Spanish, differing in prosodic types, were analyzed. These languages showed difference in acoustic characteristics of the source component. (4) Perceptual experiment: A language identification test for the above four languages was performed using the source signal with its acoustic features parameterized. It revealed that humans can discriminate prosodic types solely with the source features and that the discrimination is easier as acoustic information increases. The

Analysis of acoustic emission during abrasive waterjet machining of sheet metals

NASA Astrophysics Data System (ADS)

Mokhtar, Nazrin; Gebremariam, MA; Zohari, H.; Azhari, Azmir

2018-04-01

The present paper reports on the analysis of acoustic emission (AE) produced during abrasive waterjet (AWJ) machining process. This paper focuses on the relationship of AE and surface quality of sheet metals. The changes in acoustic emission signals recorded by the mean of power spectral density (PSD) via covariance method in relation to the surface quality of the cut are discussed. The test was made using two materials for comparison namely aluminium 6061 and stainless steel 304 with five different feed rates. The acoustic emission data were captured by Labview and later processed using MATLAB software. The results show that the AE spectrums correlated with different feed rates and surface qualities. It can be concluded that the AE is capable of monitoring the changes of feed rate and surface quality.

Comparison of alternatives to amplitude thresholding for onset detection of acoustic emission signals

NASA Astrophysics Data System (ADS)

Bai, F.; Gagar, D.; Foote, P.; Zhao, Y.

2017-02-01

Acoustic Emission (AE) monitoring can be used to detect the presence of damage as well as determine its location in Structural Health Monitoring (SHM) applications. Information on the time difference of the signal generated by the damage event arriving at different sensors in an array is essential in performing localisation. Currently, this is determined using a fixed threshold which is particularly prone to errors when not set to optimal values. This paper presents three new methods for determining the onset of AE signals without the need for a predetermined threshold. The performance of the techniques is evaluated using AE signals generated during fatigue crack growth and compared to the established Akaike Information Criterion (AIC) and fixed threshold methods. It was found that the 1D location accuracy of the new methods was within the range of < 1 - 7.1 % of the monitored region compared to 2.7% for the AIC method and a range of 1.8-9.4% for the conventional Fixed Threshold method at different threshold levels.

Acoustic and Seismic Fields of Hydraulic Jumps at Varying Froude Numbers

NASA Astrophysics Data System (ADS)

Ronan, Timothy J.; Lees, Jonathan M.; Mikesell, T. Dylan; Anderson, Jacob F.; Johnson, Jeffrey B.

2017-10-01

Mechanisms that produce seismic and acoustic wavefields near rivers are poorly understood because of a lack of observations relating temporally dependent river conditions to the near-river seismoacoustic fields. This controlled study at the Harry W. Morrison Dam (HWMD) on the Boise River, Idaho, explores how temporal variation in fluvial systems affects surrounding acoustic and seismic fields. Adjusting the configuration of the HWMD changed the river bathymetry and therefore the form of the standing wave below the dam. The HWMD was adjusted to generate four distinct wave regimes that were parameterized through their dimensionless Froude numbers (Fr) and observations of the ambient seismic and acoustic wavefields at the study site. To generate detectable and coherent signals, a standing wave must exceed a threshold Fr value of 1.7, where a nonbreaking undular jump turns into a breaking weak hydraulic jump. Hydrodynamic processes may partially control the spectral content of the seismic and acoustic energies. Furthermore, spectra related to reproducible wave conditions can be used to calibrate and verify fluvial seismic and acoustic models.

Acoustic Translation of an Acoustically Levitated Sample

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Allen, J. L.

1986-01-01

Acoustic-levitation apparatus uses only one acoustic mode to move sample from one region of chamber to another. Sample heated and cooled quickly by translation between hot and cold regions of levitation chamber. Levitated sample is raised into furnace region by raising plunger. Frequency of sound produced by transducers adjusted by feedback system to maintain (102) resonant mode, which levitates sample midway between transducers and plunger regardless of plunger position.

Novel Methods for Sensing Acoustical Emissions From the Knee for Wearable Joint Health Assessment.

PubMed

Teague, Caitlin N; Hersek, Sinan; Toreyin, Hakan; Millard-Stafford, Mindy L; Jones, Michael L; Kogler, Geza F; Sawka, Michael N; Inan, Omer T

2016-08-01

We present the framework for wearable joint rehabilitation assessment following musculoskeletal injury. We propose a multimodal sensing (i.e., contact based and airborne measurement of joint acoustic emission) system for at-home monitoring. We used three types of microphones-electret, MEMS, and piezoelectric film microphones-to obtain joint sounds in healthy collegiate athletes during unloaded flexion/extension, and we evaluated the robustness of each microphone's measurements via: 1) signal quality and 2) within-day consistency. First, air microphones acquired higher quality signals than contact microphones (signal-to-noise-and-interference ratio of 11.7 and 12.4 dB for electret and MEMS, respectively, versus 8.4 dB for piezoelectric). Furthermore, air microphones measured similar acoustic signatures on the skin and 5 cm off the skin (∼4.5× smaller amplitude). Second, the main acoustic event during repetitive motions occurred at consistent joint angles (intra-class correlation coefficient ICC(1, 1) = 0.94 and ICC(1, k) = 0.99). Additionally, we found that this angular location was similar between right and left legs, with asymmetry observed in only a few individuals. We recommend using air microphones for wearable joint sound sensing; for practical implementation of contact microphones in a wearable device, interface noise must be reduced. Importantly, we show that airborne signals can be measured consistently and that healthy left and right knees often produce a similar pattern in acoustic emissions. These proposed methods have the potential for enabling knee joint acoustics measurement outside the clinic/lab and permitting long-term monitoring of knee health for patients rehabilitating an acute knee joint injury.

Alignment of an acoustic manipulation device with cepstral analysis of electronic impedance data.

PubMed

Hughes, D A; Qiu, Y; Démoré, C; Weijer, C J; Cochran, S

2015-02-01

Acoustic particle manipulation is an emerging technology that uses ultrasonic standing waves to position objects with pressure gradients and acoustic radiation forces. To produce strong standing waves, the transducer and the reflector must be aligned properly such that they are parallel to each other. This can be a difficult process due to the need to visualise the ultrasound waves and as higher frequencies are introduced, this alignment requires higher accuracy. In this paper, we present a method for aligning acoustic resonators with cepstral analysis. This is a simple signal processing technique that requires only the electrical impedance measurement data of the resonator, which is usually recorded during the fabrication process of the device. We first introduce the mathematical basis of cepstral analysis and then demonstrate and validate it using a computer simulation of an acoustic resonator. Finally, the technique is demonstrated experimentally to create many parallel linear traps for 10 μm fluorescent beads inside an acoustic resonator. Copyright © 2014 Elsevier B.V. All rights reserved.

Multimode Acoustic Research

NASA Technical Reports Server (NTRS)

Barmatz, M.

1985-01-01

There is a need for high temperature containerless processing facilities that can efficiently position and manipulate molten samples in the reduced gravity environment of space. The goal of the research is to develop sophisticated high temperature manipulation capabilities such as selection of arbitrary axes rotation and rapid sample cooling. This program will investigate new classes of acoustic levitation in rectangular, cylindrical and spherical geometries. The program tasks include calculating theoretical expressions of the acoustic forces in these geometries for the excitation of up to three acoustic modes (multimodes). These calculations are used to: (1) determine those acoustic modes that produce stable levitation, (2) isolate the levitation and rotation capabilities to produce more than one axis of rotation, and (3) develop methods to translate samples down long tube cylindrical chambers. Experimental levitators will then be constructed to verify the stable levitation and rotation predictions of the models.

Novel Fiber-Optic Ring Acoustic Emission Sensor

PubMed Central

Han, Xiaole; Xia, Dong; Liu, Taolin; Lang, Hao

2018-01-01

Acoustic emission technology has been applied to many fields for many years. However, the conventional piezoelectric acoustic emission sensors cannot be used in extreme environments, such as those with heavy electromagnetic interference, high pressure, or strong corrosion. In this paper, a novel fiber-optic ring acoustic emission sensor is proposed. The sensor exhibits high sensitivity, anti-electromagnetic interference, and corrosion resistance. First, the principle of a novel fiber-optic ring sensor is introduced. Different from piezoelectric and other fiber acoustic emission sensors, this novel sensor includes both a sensing skeleton and a sensing fiber. Second, a heterodyne interferometric demodulating method is presented. In addition, a fiber-optic ring sensor acoustic emission system is built based on this method. Finally, fiber-optic ring acoustic emission experiments are performed. The novel fiber-optic ring sensor is glued onto the surface of an aluminum plate. The 150 kHz standard continuous sinusoidal signals and broken lead signals are successfully detected by the novel fiber-optic ring acoustic emission sensor. In addition, comparison to the piezoelectric acoustic emission sensor is performed, which shows the availability and reliability of the novel fiber-optic ring acoustic emission sensor. In the future, this novel fiber-optic ring acoustic emission sensor will provide a new route to acoustic emission detection in harsh environments. PMID:29342858

Carrier frequency offset estimation for an acoustic-electric channel using 16 QAM modulation

NASA Astrophysics Data System (ADS)

Cunningham, Michael T.; Anderson, Leonard A.; Wilt, Kyle R.; Chakraborty, Soumya; Saulnier, Gary J.; Scarton, Henry A.

2016-05-01

Acoustic-electric channels can be used to send data through metallic barriers, enabling communications where electromagnetic signals are ineffective. This paper considers an acoustic-electric channel that is formed by mounting piezoelectric transducers on metallic barriers that are separated by a thin water layer. The transducers are coupled to the barriers using epoxy and the barriers are positioned to axially-align the PZTs, maximizing energy transfer efficiency. The electrical signals are converted by the transmitting transducers into acoustic waves, which propagate through the elastic walls and water medium to the receiving transducers. The reverberation of the acoustic signals in these channels can produce multipath distortion with a significant delay spread that introduces inter-symbol interference (ISI) into the received signal. While the multipath effects can be severe, the channel does not change rapidly which makes equalization easier. Here we implement a 16-QAM system on this channel, including a method for obtaining accurate carrier frequency offset (CFO) estimates in the presence of the quasi-static multipath propagation. A raised-power approach is considered but found to suffer from excessive data noise resulting from the ISI. An alternative approach that utilizes a pilot tone burst at the start of a data packet is used for CFO estimation and found to be effective. The autocorrelation method is used to estimate the frequency of the received burst. A real-time prototype of the 16 QAM system that uses a Texas Instruments MSP430 microcontroller-based transmitter and a personal computer-based receiver is presented along with performance results.

Transition section for acoustic waveguides

DOEpatents

Karplus, H.H.B.

1975-10-28

A means of facilitating the transmission of acoustic waves with minimal reflection between two regions having different specific acoustic impedances is described comprising a region exhibiting a constant product of cross-sectional area and specific acoustic impedance at each cross-sectional plane along the axis of the transition region. A variety of structures that exhibit this feature is disclosed, the preferred embodiment comprising a nested structure of doubly reentrant cones. This structure is useful for monitoring the operation of nuclear reactors in which random acoustic signals are generated in the course of operation.

Laser-induced acoustic imaging of underground objects

NASA Astrophysics Data System (ADS)

Li, Wen; DiMarzio, Charles A.; McKnight, Stephen W.; Sauermann, Gerhard O.; Miller, Eric L.

1999-02-01

This paper introduces a new demining technique based on the photo-acoustic interaction, together with results from photo- acoustic experiments. We have buried different types of targets (metal, rubber and plastic) in different media (sand, soil and water) and imaged them by measuring reflection of acoustic waves generated by irradiation with a CO2 laser. Research has been focused on the signal acquisition and signal processing. A deconvolution method using Wiener filters is utilized in data processing. Using a uniform spatial distribution of laser pulses at the ground's surface, we obtained 3D images of buried objects. The images give us a clear representation of the shapes of the underground objects. The quality of the images depends on the mismatch of acoustic impedance of the buried objects, the bandwidth and center frequency of the acoustic sensors and the selection of filter functions.

Mortar and artillery variants classification by exploiting characteristics of the acoustic signature

NASA Astrophysics Data System (ADS)

Hohil, Myron E.; Grasing, David; Desai, Sachi; Morcos, Amir

2007-10-01

Feature extraction methods based on the discrete wavelet transform and multiresolution analysis facilitate the development of a robust classification algorithm that reliably discriminates mortar and artillery variants via acoustic signals produced during the launch/impact events. Utilizing acoustic sensors to exploit the sound waveform generated from the blast for the identification of mortar and artillery variants. Distinct characteristics arise within the different mortar variants because varying HE mortar payloads and related charges emphasize concussive and shrapnel effects upon impact employing varying magnitude explosions. The different mortar variants are characterized by variations in the resulting waveform of the event. The waveform holds various harmonic properties distinct to a given mortar/artillery variant that through advanced signal processing techniques can employed to classify a given set. The DWT and other readily available signal processing techniques will be used to extract the predominant components of these characteristics from the acoustic signatures at ranges exceeding 2km. Exploiting these techniques will help develop a feature set highly independent of range, providing discrimination based on acoustic elements of the blast wave. Highly reliable discrimination will be achieved with a feed-forward neural network classifier trained on a feature space derived from the distribution of wavelet coefficients, frequency spectrum, and higher frequency details found within different levels of the multiresolution decomposition. The process that will be described herein extends current technologies, which emphasis multi modal sensor fusion suites to provide such situational awareness. A two fold problem of energy consumption and line of sight arise with the multi modal sensor suites. The process described within will exploit the acoustic properties of the event to provide variant classification as added situational awareness to the solider.

Acoustically based fetal heart rate monitor

NASA Technical Reports Server (NTRS)

Baker, Donald A.; Zuckerwar, Allan J.

1991-01-01

The acoustically based fetal heart rate monitor permits an expectant mother to perform the fetal Non-Stress Test in her home. The potential market would include the one million U.S. pregnancies per year requiring this type of prenatal surveillance. The monitor uses polyvinylidene fluoride (PVF2) piezoelectric polymer film for the acoustic sensors, which are mounted in a seven-element array on a cummerbund. Evaluation of the sensor ouput signals utilizes a digital signal processor, which performs a linear prediction routine in real time. Clinical tests reveal that the acoustically based monitor provides Non-Stress Test records which are comparable to those obtained with a commercial ultrasonic transducer.

Periodic shock-emission from acoustically driven cavitation clouds: a source of the subharmonic signal.

PubMed

Johnston, Keith; Tapia-Siles, Cecilia; Gerold, Bjoern; Postema, Michiel; Cochran, Sandy; Cuschieri, Alfred; Prentice, Paul

2014-12-01

Single clouds of cavitation bubbles, driven by 254kHz focused ultrasound at pressure amplitudes in the range of 0.48-1.22MPa, have been observed via high-speed shadowgraphic imaging at 1×10(6) frames per second. Clouds underwent repetitive growth, oscillation and collapse (GOC) cycles, with shock-waves emitted periodically at the instant of collapse during each cycle. The frequency of cloud collapse, and coincident shock-emission, was primarily dependent on the intensity of the focused ultrasound driving the activity. The lowest peak-to-peak pressure amplitude of 0.48MPa generated shock-waves with an average period of 7.9±0.5μs, corresponding to a frequency of f0/2, half-harmonic to the fundamental driving. Increasing the intensity gave rise to GOC cycles and shock-emission periods of 11.8±0.3, 15.8±0.3, 19.8±0.2μs, at pressure amplitudes of 0.64, 0.92 and 1.22MPa, corresponding to the higher-order subharmonics of f0/3, f0/4 and f0/5, respectively. Parallel passive acoustic detection, filtered for the fundamental driving, revealed features that correlated temporally to the shock-emissions observed via high-speed imaging, p(two-tailed) < 0.01 (r=0.996, taken over all data). Subtracting the isolated acoustic shock profiles from the raw signal collected from the detector, demonstrated the removal of subharmonic spectral peaks, in the frequency domain. The larger cavitation clouds (>200μm diameter, at maximum inflation), that developed under insonations of peak-to-peak pressure amplitudes >1.0MPa, emitted shock-waves with two or more fronts suggesting non-uniform collapse of the cloud. The observations indicate that periodic shock-emissions from acoustically driven cavitation clouds provide a source for the cavitation subharmonic signal, and that shock structure may be used to study intra-cloud dynamics at sub-microsecond timescales. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Long-term recording and automatic analysis of cough using filtered acoustic signals and movements on static charge sensitive bed.

PubMed

Salmi, T; Sovijärvi, A R; Brander, P; Piirilä, P

1988-11-01

Reliable long-term assessment of cough is necessary in many clinical and scientific settings. A new method for long-term recording and automatic analysis of cough is presented. The method is based on simultaneous recording of two independent signals: high-pass filtered cough sounds and cough-induced fast movements of the body. The acoustic signals are recorded with a dynamic microphone in the acoustic focus of a glass fiber paraboloid mirror. Body movements are recorded with a static charge-sensitive bed located under an ordinary plastic foam mattress. The patient can be studied lying or sitting with no transducers or electrodes attached. A microcomputer is used for sampling of signals, detection of cough, statistical analyses, and on-line printing of results. The method was validated in seven adult patients with a total of 809 spontaneous cough events, using clinical observation as a reference. The sensitivity of the method to detect cough was 99.0 percent, and the positive predictivity was 98.1 percent. The system ignored speaking and snoring. The method provides a convenient means of reliable long-term follow-up of cough in clinical work and research.

Acoustic Emission Analysis of Shuttle Thermal Protection System

NASA Technical Reports Server (NTRS)

Lane, John; Hooker, Jeffery; Immer, Christopher; Walker, James

2004-01-01

Acoustic emission (AE) signals generated from projectile impacts on reinforced and advanced carbon/carbon (RCC and ACC) panels, fired from a compressed-gas gun, identify the type and severity of damage sustained by the target. This type of testing is vital in providing the required "return to flight" (RTF) data needed to ensure continued and safe operation of NASA's Space Shuttle fleet. The gas gun at Kennedy Space Center is capable of propelling 12-inch by 3-inch cylinders of external tank (ET) foam at exit velocities exceeding 1,000 feet per second. Conventional AE analysis techniques require time domain processing of impulse data, along with amplitude distribution analysis. It is well known that identical source excitations can produce a wide range of AE signals amplitudes. In order to satisfy RTF goals, it is necessary to identify impact energy levels above and below damage thresholds. Spectral analysis techniques involving joint time frequency analysis (JTFA) are used to reinforce time domain AE analysis. JTFA analysis of the AE signals consists of short-time Fourier transforms (STFT) and the Huang-Hilbert transform (HHT). The HHT provides a very good measure of the instantaneous frequency of impulse events dominated by a single component. Identifying failure modes and cracking of fibers from flexural and/or extensional mode acoustic signals will help support in-flight as well as postflight impact analysis.

Novel underwater soundscape: acoustic repertoire of plainfin midshipman fish.

PubMed

McIver, Eileen L; Marchaterre, Margaret A; Rice, Aaron N; Bass, Andrew H

2014-07-01

Toadfishes are among the best-known groups of sound-producing (vocal) fishes and include species commonly known as toadfish and midshipman. Although midshipman have been the subject of extensive investigation of the neural mechanisms of vocalization, this is the first comprehensive, quantitative analysis of the spectro-temporal characters of their acoustic signals and one of the few for fishes in general. Field recordings of territorial, nest-guarding male midshipman during the breeding season identified a diverse vocal repertoire composed of three basic sound types that varied widely in duration, harmonic structure and degree of amplitude modulation (AM): 'hum', 'grunt' and 'growl'. Hum duration varied nearly 1000-fold, lasting for minutes at a time, with stable harmonic stacks and little envelope modulation throughout the sound. By contrast, grunts were brief, ~30-140 ms, broadband signals produced both in isolation and repetitively as a train of up to 200 at intervals of ~0.5-1.0 s. Growls were also produced alone or repetitively, but at variable intervals of the order of seconds with durations between those of grunts and hums, ranging 60-fold from ~200 ms to 12 s. Growls exhibited prominent harmonics with sudden shifts in pulse repetition rate and highly variable AM patterns, unlike the nearly constant AM of grunt trains and flat envelope of hums. Behavioral and neurophysiological studies support the hypothesis that each sound type's unique acoustic signature contributes to signal recognition mechanisms. Nocturnal production of these sounds against a background chorus dominated constantly for hours by a single sound type, the multi-harmonic hum, reveals a novel underwater soundscape for fish. © 2014. Published by The Company of Biologists Ltd.

Signal characteristics of electroseismic conversion

NASA Astrophysics Data System (ADS)

Peng, Rong; Di, Bangrang; Wei, Jianxin; Ding, Pinbo; Liu, Zichun; Guan, Bingyan; Huang, Shiqi

2018-04-01

Electric fields applying on the fluid-filled porous materials can induce small relative pore-fluid motions due to electroseismic conversions. In order to characterize the electroseismic propagation phenomena, we have designed an experimental apparatus to acquire the electroseismic (ES) signals. The electroseismic measurements on different samples have been conducted to confirm the origin of the recorded signals. We find that a strong acoustic signal generates around the electrode and affects the identification of ES signals. To further confirm and distinguish the ES signal as well as the acoustic signal around the electrode, we have analyzed records obtained with regular movements of the receiver, the sample and the source. Analysis has been made on the characteristics of the traveltime, polarity and frequency of ES signals. Our results show that the traveltime of ES signal relates to the distance between the rock sample and the receiver, the location of the exciting electrode has little impact on the traveltime. The applied electric field influences the polarity of ES signal, the polarity of ES signal reverses along with the changes of the electric field direction. While it has no polarity effects on the acoustic signal generated around the electrode. The frequency spectrum of ES signal is absolutely different with that of the acoustic signal generated around the electrode. The acoustic signal around the electrode has multiple dominant frequencies which are mainly in low-frequency range without being affected by the frequency of the electric field. The ES signal has only one dominant frequency which closely relates to the frequency of the electric field. The understanding of the signal characteristics on electroseismic conversion can contribute to a better application and interpretation of ES exploration.

Acoustic cross-correlation flowmeter for solid-gas flow

DOEpatents

Sheen, S.H.; Raptis, A.C.

1984-05-14

Apparatus for measuring particle velocity in a solid-gas flow within a pipe includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals; and means for cross-correlating said first and second output signals.

Acoustic cross-correlation flowmeter for solid-gas flow

DOEpatents

Sheen, Shuh-Haw; Raptis, Apostolos C.

1986-01-01

Apparatus for measuring particle velocity in a solid-gas flow within a pipe includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals in response to said first and second detected signals; and means for cross-correlating said first and second output signals.

Acoustic energy harvesting based on a planar acoustic metamaterial

NASA Astrophysics Data System (ADS)

Qi, Shuibao; Oudich, Mourad; Li, Yong; Assouar, Badreddine

2016-06-01

We theoretically report on an innovative and practical acoustic energy harvester based on a defected acoustic metamaterial (AMM) with piezoelectric material. The idea is to create suitable resonant defects in an AMM to confine the strain energy originating from an acoustic incidence. This scavenged energy is converted into electrical energy by attaching a structured piezoelectric material into the defect area of the AMM. We show an acoustic energy harvester based on a meta-structure capable of producing electrical power from an acoustic pressure. Numerical simulations are provided to analyze and elucidate the principles and the performances of the proposed system. A maximum output voltage of 1.3 V and a power density of 0.54 μW/cm3 are obtained at a frequency of 2257.5 Hz. The proposed concept should have broad applications on energy harvesting as well as on low-frequency sound isolation, since this system acts as both acoustic insulator and energy harvester.

Male Responses to Conspecific Advertisement Signals in the Field Cricket Gryllus rubens (Orthoptera: Gryllidae)

PubMed Central

Jang, Yikweon

2011-01-01

In many species males aggregate and produce long-range advertisement signals to attract conspecific females. The majority of the receivers of these signals are probably other males most of the time, and male responses to competitors' signals can structure the spatial and temporal organization of the breeding aggregation and affect male mating tactics. I quantified male responses to a conspecific advertisement stimulus repeatedly over three age classes in Gryllus rubens (Orthoptera: Gryllidae) in order to estimate the type and frequency of male responses to the broadcast stimulus and to determine the factors affecting them. Factors tested included body size, wing dimorphism, age, and intensity of the broadcast stimulus. Overall, males employed acoustic response more often than positive phonotactic response. As males aged, the frequency of positive phonotactic response decreased but that of the acoustic response increased. That is, males may use positive phonotaxis in the early stages of their adult lives, possibly to find suitable calling sites or parasitize calling males, and then later in life switch to acoustic responses in response to conspecific advertisement signals. Males with smaller body size more frequently exhibited acoustic responses. This study suggests that individual variation, more than any factors measured, is critical for age-dependent male responses to conspecific advertisement signals. PMID:21283758

Male responses to conspecific advertisement signals in the field cricket Gryllus rubens (Orthoptera: Gryllidae).

PubMed

Jang, Yikweon

2011-01-20

In many species males aggregate and produce long-range advertisement signals to attract conspecific females. The majority of the receivers of these signals are probably other males most of the time, and male responses to competitors' signals can structure the spatial and temporal organization of the breeding aggregation and affect male mating tactics. I quantified male responses to a conspecific advertisement stimulus repeatedly over three age classes in Gryllus rubens (Orthoptera: Gryllidae) in order to estimate the type and frequency of male responses to the broadcast stimulus and to determine the factors affecting them. Factors tested included body size, wing dimorphism, age, and intensity of the broadcast stimulus. Overall, males employed acoustic response more often than positive phonotactic response. As males aged, the frequency of positive phonotactic response decreased but that of the acoustic response increased. That is, males may use positive phonotaxis in the early stages of their adult lives, possibly to find suitable calling sites or parasitize calling males, and then later in life switch to acoustic responses in response to conspecific advertisement signals. Males with smaller body size more frequently exhibited acoustic responses. This study suggests that individual variation, more than any factors measured, is critical for age-dependent male responses to conspecific advertisement signals.

Ultrasonic signal enhancement by resonator techniques

NASA Technical Reports Server (NTRS)

Heyman, J. S.

1973-01-01

Ultrasonic resonators increase experimental sensitivity to acoustic dispersion and changes in attenuation. Experimental sensitivity enhancement line shapes are presented which were obtained by modulating the acoustic properties of a CdS resonator with a light beam. Small changes in light level are made to produce almost pure absorptive or dispersive changes in the resonator signal. This effect is due to the coupling of the ultrasonic wave to the CdS conductivity which is proportional to incident light intensity. The resonator conductivity is adjusted in this manner to obtain both dispersive and absorptive sensitivity enhancement line shapes. The data presented verify previous thoretical calculations based on a propagating wave model.

Acoustic Manifestations of Natural versus Triggered Lightning

NASA Astrophysics Data System (ADS)

Arechiga, R. O.; Johnson, J. B.; Edens, H. E.; Rison, W.; Thomas, R. J.; Eack, K.; Eastvedt, E. M.; Aulich, G. D.; Trueblood, J.

2010-12-01

Positive leaders are rarely detected by VHF lightning detection systems; positive leader channels are usually outlined only by recoil events. Positive cloud-to-ground (CG) channels are usually not mapped. The goal of this work is to study the types of thunder produced by natural versus triggered lightning and to assess which types of thunder signals have electromagnetic activity detected by the lightning mapping array (LMA). Towards this end we are investigating the lightning detection capabilities of acoustic techniques, and comparing them with the LMA. In a previous study we used array beam forming and time of flight information to locate acoustic sources associated with lightning. Even though there was some mismatch, generally LMA and acoustic techniques saw the same phenomena. To increase the database of acoustic data from lightning, we deployed a network of three infrasound arrays (30 m aperture) during the summer of 2010 (August 3 to present) in the Magdalena mountains of New Mexico, to monitor infrasound (below 20 Hz) and audio range sources due to natural and triggered lightning. The arrays were located at a range of distances (60 to 1400 m) surrounding the triggering site, called the Kiva, used by Langmuir Laboratory to launch rockets. We have continuous acoustic measurements of lightning data from July 20 to September 18 of 2009, and from August 3 to September 1 of 2010. So far, lightning activity around the Kiva was higher during the summer of 2009. We will present acoustic data from several interesting lightning flashes including a comparison between a natural and a triggered one.

Micropower Mixed-signal VLSI Independent Component Analysis for Gradient Flow Acoustic Source Separation.

PubMed

Stanaćević, Milutin; Li, Shuo; Cauwenberghs, Gert

2016-07-01

A parallel micro-power mixed-signal VLSI implementation of independent component analysis (ICA) with reconfigurable outer-product learning rules is presented. With the gradient sensing of the acoustic field over a miniature microphone array as a pre-processing method, the proposed ICA implementation can separate and localize up to 3 sources in mild reverberant environment. The ICA processor is implemented in 0.5 µm CMOS technology and occupies 3 mm × 3 mm area. At 16 kHz sampling rate, ASIC consumes 195 µW power from a 3 V supply. The outer-product implementation of natural gradient and Herault-Jutten ICA update rules demonstrates comparable performance to benchmark FastICA algorithm in ideal conditions and more robust performance in noisy and reverberant environment. Experiments demonstrate perceptually clear separation and precise localization over wide range of separation angles of two speech sources presented through speakers positioned at 1.5 m from the array on a conference room table. The presented ASIC leads to a extreme small form factor and low power consumption microsystem for source separation and localization required in applications like intelligent hearing aids and wireless distributed acoustic sensor arrays.

The effects of external acoustic pressure fields on a free-running supercavitating projectile.

PubMed

Cameron, Peter J K; Rogers, Peter H; Doane, John W

2010-12-01

Proliferation of supercavitating torpedoes has motivated research on countermeasures against them as well as on the fluid phenomenon which makes them possible. The goal of this research was to investigate an envisaged countermeasure, an acoustic field capable of slowing or diverting the weapon by disrupting the cavitation envelope. The research focused on the interactions between high pressure amplitude sound waves and a supercavity produced by a small free-flying projectile. The flight dynamics and cavity geometry measurements were compared to control experiments and theoretical considerations were made for evaluating the effects. Corrugations on the cavity/water interface caused by the pressure signal have been observed and characterized. Results also show that the accuracy of a supercavitating projectile can be adversely affected by the sound signal. This research concludes with results that indicate that it is acoustic cavitation in the medium surrounding the supercavity, caused by the high pressure amplitude sound, that is responsible for the reduced accuracy. A hypothesis has been presented addressing the means by which the acoustic cavitation could cause this effect.

Translational-circular scanning for magneto-acoustic tomography with current injection.

PubMed

Wang, Shigang; Ma, Ren; Zhang, Shunqi; Yin, Tao; Liu, Zhipeng

2016-01-27

Magneto-acoustic tomography with current injection involves using electrical impedance imaging technology. To explore the potential applications in imaging biological tissue and enhance image quality, a new scan mode for the transducer is proposed that is based on translational and circular scanning to record acoustic signals from sources. An imaging algorithm to analyze these signals is developed in respect to this alternative scanning scheme. Numerical simulations and physical experiments were conducted to evaluate the effectiveness of this scheme. An experiment using a graphite sheet as a tissue-mimicking phantom medium was conducted to verify simulation results. A pulsed voltage signal was applied across the sample, and acoustic signals were recorded as the transducer performed stepped translational or circular scans. The imaging algorithm was used to obtain an acoustic-source image based on the signals. In simulations, the acoustic-source image is correlated with the conductivity at the sample boundaries of the sample, but image results change depending on distance and angular aspect of the transducer. In general, as angle and distance decreases, the image quality improves. Moreover, experimental data confirmed the correlation. The acoustic-source images resulting from the alternative scanning mode has yielded the outline of a phantom medium. This scan mode enables improvements to be made in the sensitivity of the detecting unit and a change to a transducer array that would improve the efficiency and accuracy of acoustic-source images.

Acoustic microscope surface inspection system and method

DOEpatents

Khuri-Yakub, Butrus T.; Parent, Philippe; Reinholdtsen, Paul A.

1991-01-01

An acoustic microscope surface inspection system and method in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respected to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations.

Acoustic discrimination of Southern Ocean zooplankton

NASA Astrophysics Data System (ADS)

Brierley, Andrew S.; Ward, Peter; Watkins, Jonathan L.; Goss, Catherine

Acoustic surveys in the vicinity of the sub-Antarctic island of South Georgia during a period of exceptionally calm weather revealed the existence of a number of horizontally extensive yet vertically discrete scattering layers in the upper 250 m of the water column. These layers were fished with a Longhurst-Hardy plankton recorder (LHPR) and a multiple-opening 8 m 2 rectangular mid-water trawl (RMT8). Analysis of catches suggested that each scattering layer was composed predominantly of a single species (biovolume>95%) of either the euphausiids Euphausia frigida or Thysanöessa macrura, the hyperiid amphipod Themisto gaudichaudii, or the eucalaniid copepod Rhincalanus gigas. Instrumentation on the nets allowed their trajectories to be reconstructed precisely, and thus catch data to be related directly to the corresponding acoustic signals. Discriminant function analysis of differences between mean volume backscattering strength at 38, 120 and 200 kHz separated echoes originating from each of the dominant scattering layers, and other signals identified as originating from Antarctic krill ( Euphausia superba), with an overall correct classification rate of 77%. Using echo intensity data alone, gathered using hardware commonly employed for fishery acoustics, it is therefore possible to discriminate in situ between several zooplanktonic taxa, taxa which in some instances exhibit similar gross morphological characteristics and have overlapping length- frequency distributions. Acoustic signals from the mysid Antarctomysis maxima could also be discriminated once information on target distribution was considered, highlighting the value of incorporating multiple descriptors of echo characteristics into signal identification procedures. The ability to discriminate acoustically between zooplankton taxa could be applied to provide improved acoustic estimates of species abundance, and to enhance field studies of zooplankton ecology, distribution and species interactions.

Acoustic Data Processing and Transient Signal Analysis for the Hybrid Wing Body 14- by 22-Foot Subsonic Wind Tunnel Test

NASA Technical Reports Server (NTRS)

Bahr, Christopher J.; Brooks, Thomas F.; Humphreys, William M.; Spalt, Taylor B.; Stead, Daniel J.

2014-01-01

An advanced vehicle concept, the HWB N2A-EXTE aircraft design, was tested in NASA Langley's 14- by 22-Foot Subsonic Wind Tunnel to study its acoustic characteristics for var- ious propulsion system installation and airframe con gurations. A signi cant upgrade to existing data processing systems was implemented, with a focus on portability and a re- duction in turnaround time. These requirements were met by updating codes originally written for a cluster environment and transferring them to a local workstation while en- abling GPU computing. Post-test, additional processing of the time series was required to remove transient hydrodynamic gusts from some of the microphone time series. A novel automated procedure was developed to analyze and reject contaminated blocks of data, under the assumption that the desired acoustic signal of interest was a band-limited sta- tionary random process, and of lower variance than the hydrodynamic contamination. The procedure is shown to successfully identify and remove contaminated blocks of data and retain the desired acoustic signal. Additional corrections to the data, mainly background subtraction, shear layer refraction calculations, atmospheric attenuation and microphone directivity corrections, were all necessary for initial analysis and noise assessments. These were implemented for the post-processing of spectral data, and are shown to behave as expected.

Acoustic interference and recognition space within a complex assemblage of dendrobatid frogs

PubMed Central

Amézquita, Adolfo; Flechas, Sandra Victoria; Lima, Albertina Pimentel; Gasser, Herbert; Hödl, Walter

2011-01-01

In species-rich assemblages of acoustically communicating animals, heterospecific sounds may constrain not only the evolution of signal traits but also the much less-studied signal-processing mechanisms that define the recognition space of a signal. To test the hypothesis that the recognition space is optimally designed, i.e., that it is narrower toward the species that represent the higher potential for acoustic interference, we studied an acoustic assemblage of 10 diurnally active frog species. We characterized their calls, estimated pairwise correlations in calling activity, and, to model the recognition spaces of five species, conducted playback experiments with 577 synthetic signals on 531 males. Acoustic co-occurrence was not related to multivariate distance in call parameters, suggesting a minor role for spectral or temporal segregation among species uttering similar calls. In most cases, the recognition space overlapped but was greater than the signal space, indicating that signal-processing traits do not act as strictly matched filters against sounds other than homospecific calls. Indeed, the range of the recognition space was strongly predicted by the acoustic distance to neighboring species in the signal space. Thus, our data provide compelling evidence of a role of heterospecific calls in evolutionarily shaping the frogs' recognition space within a complex acoustic assemblage without obvious concomitant effects on the signal. PMID:21969562

Deciphering acoustic emission signals in drought stressed branches: the missing link between source and sensor.

PubMed

Vergeynst, Lidewei L; Sause, Markus G R; Hamstad, Marvin A; Steppe, Kathy

2015-01-01

When drought occurs in plants, acoustic emission (AE) signals can be detected, but the actual causes of these signals are still unknown. By analyzing the waveforms of the measured signals, it should, however, be possible to trace the characteristics of the AE source and get information about the underlying physiological processes. A problem encountered during this analysis is that the waveform changes significantly from source to sensor and lack of knowledge on wave propagation impedes research progress made in this field. We used finite element modeling and the well-known pencil lead break source to investigate wave propagation in a branch. A cylindrical rod of polyvinyl chloride was first used to identify the theoretical propagation modes. Two wave propagation modes could be distinguished and we used the finite element model to interpret their behavior in terms of source position for both the PVC rod and a wooden rod. Both wave propagation modes were also identified in drying-induced signals from woody branches, and we used the obtained insights to provide recommendations for further AE research in plant science.

Passive pavement-mounted acoustical linguistic drive alert system and method

DOEpatents

Kisner, Roger A.; Anderson, Richard L.; Carnal, Charles L.; Hylton, James O.; Stevens, Samuel S.

2001-01-01

Systems and methods are described for passive pavement-mounted acoustical alert of the occupants of a vehicle. A method of notifying a vehicle occupant includes providing a driving medium upon which a vehicle is to be driven; and texturing a portion of the driving medium such that the textured portion interacts with the vehicle to produce audible signals, the textured portion pattern such that a linguistic message is encoded into the audible signals. The systems and methods provide advantages because information can be conveyed to the occupants of the vehicle based on the location of the vehicle relative to the textured surface.

Acoustic emission evolution during sliding friction of Hadfield steel single crystal

NASA Astrophysics Data System (ADS)

Lychagin, D. V.; Novitskaya, O. S.; Kolubaev, A. V.; Sizova, O. V.

2017-12-01

Friction is a complex dynamic process. Direct observation of processes occurring in the friction zone is impossible due to a small size of a real contact area and, as a consequence, requires various additional methods applicable to monitor a tribological contact state. One of such methods consists in the analysis of acoustic emission data of a tribological contact. The use of acoustic emission entails the problem of interpreting physical sources of signals. In this paper, we analyze the evolution of acoustic emission signal frames in friction of Hadfield steel single crystals. The chosen crystallographic orientation of single crystals enables to identify four stages related to friction development as well as acoustic emission signals inherent in these stages. Acoustic emission signal parameters are studied in more detail by the short-time Fourier transform used to determine the time variation of the median frequency and its power spectrum. The results obtained will facilitate the development of a more precise method to monitor the tribological contact based on the acoustic emission method.

Modulation by steroid hormones of a "sexy" acoustic signal in an Oscine species, the Common Canary Serinus canaria.

PubMed

Rybak, Fanny; Gahr, Manfred

2004-06-01

The respective influence of testosterone and estradiol on the structure of the Common Canary Serinus canaria song was studied by experimentally controlling blood levels of steroid hormones in males and analyzing the consequent effects on acoustic parameters. A detailed acoustic analysis of the songs produced before and after hormonal manipulation revealed that testosterone and estradiol seem to control distinct song parameters independently. The presence of receptors for testosterone and estradiol in the brain neural pathway controlling song production strongly suggests that the observed effects are mediated by a steroid action at the neuronal level.

LOCATION OF LEAKS IN PRESSURIZED PETROLEUM PIPELINES BY MEANS OF PASSIVE-ACOUSTIC METHODS

EPA Science Inventory

Experiments were conducted on the underground pipeline at the EPA's UST Test Apparatus n which three acoustic sensors separated by a maximum distance of 38m (125 ft) were used to monitor signals produced by 11.4-, 5.7-, and 3.8-L/h (3.0-, 1.5-, and 1.0-gal/h) leaks in the wall of...

Interaction of electromagnetic and acoustic waves in a stochastic atmosphere

NASA Technical Reports Server (NTRS)

Bhatnagar, N.; Peterson, A. M.

1979-01-01

In the Stanford radio acoustic sounding system (RASS) an electromagnetic signal is made to scatter from a moving acoustic pulse train. Under a Bragg-scatter condition maximum electromagnetic scattering occurs. The scattered radio signal contains temperature and wind information as a function of the acoustic-pulse position. In this investigation RASS performance is assessed in an atmosphere characterized by the presence of turbulence and mean atmospheric parameters. The only assumption made is that the electromagnetic wave is not affected by stochastic perturbations in the atmosphere. It is concluded that the received radio signal depends strongly on the intensity of turbulence for altitudes of the acoustic pulse greater than the coherence length of propagation. The effect of mean vertical wind and mean temperature on the strength of the received signal is also demonstrated to be insignificant. Mean horizontal winds, however, shift the focus of the reflected electromagnetic energy from its origin, resulting in a decrease in received signal level when a monostatic radio-frequency (RF) system is used. For a bistatic radar configuration with space diversified receiving antennas, the shifting of the acoustic pulse makes possible the remote measurement of the horizontal wind component.

Device and method for generating a beam of acoustic energy from a borehole, and applications thereof

DOEpatents

Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian; Nihei, Kurt; Schmitt, Denis P.; Skelt, Christopher

2010-11-23

In some aspects of the invention, a device, positioned within a well bore, configured to generate and direct an acoustic beam into a rock formation around a borehole is disclosed. The device comprises a source configured to generate a first signal at a first frequency and a second signal at a second frequency; a transducer configured to receive the generated first and the second signals and produce acoustic waves at the first frequency and the second frequency; and a non-linear material, coupled to the transducer, configured to generate a collimated beam with a frequency equal to the difference between the first frequency and the second frequency by a non-linear mixing process, wherein the non-linear material includes one or more of a mixture of liquids, a solid, a granular material, embedded microspheres, or an emulsion.

Acoustic data transmission through a drill string

DOEpatents

Drumheller, D.S.

1988-04-21

Acoustical signals are transmitted through a drill string by canceling upward moving acoustical noise and by preconditioning the data in recognition of the comb filter impedance characteristics of the drill string. 5 figs.

Acoustic Source Bearing Estimation (ASBE) computer program development

NASA Technical Reports Server (NTRS)

Wiese, Michael R.

1987-01-01

A new bearing estimation algorithm (Acoustic Source Analysis Technique - ASAT) and an acoustic analysis computer program (Acoustic Source Bearing Estimation - ASBE) are described, which were developed by Computer Sciences Corporation for NASA Langley Research Center. The ASBE program is used by the Acoustics Division/Applied Acoustics Branch and the Instrument Research Division/Electro-Mechanical Instrumentation Branch to analyze acoustic data and estimate the azimuths from which the source signals radiated. Included are the input and output from a benchmark test case.

Examining Acoustic and Kinematic Measures of Articulatory Working Space: Effects of Speech Intensity.

PubMed

Whitfield, Jason A; Dromey, Christopher; Palmer, Panika

2018-05-17

The purpose of this study was to examine the effect of speech intensity on acoustic and kinematic vowel space measures and conduct a preliminary examination of the relationship between kinematic and acoustic vowel space metrics calculated from continuously sampled lingual marker and formant traces. Young adult speakers produced 3 repetitions of 2 different sentences at 3 different loudness levels. Lingual kinematic and acoustic signals were collected and analyzed. Acoustic and kinematic variants of several vowel space metrics were calculated from the formant frequencies and the position of 2 lingual markers. Traditional metrics included triangular vowel space area and the vowel articulation index. Acoustic and kinematic variants of sentence-level metrics based on the articulatory-acoustic vowel space and the vowel space hull area were also calculated. Both acoustic and kinematic variants of the sentence-level metrics significantly increased with an increase in loudness, whereas no statistically significant differences in traditional vowel-point metrics were observed for either the kinematic or acoustic variants across the 3 loudness conditions. In addition, moderate-to-strong relationships between the acoustic and kinematic variants of the sentence-level vowel space metrics were observed for the majority of participants. These data suggest that both kinematic and acoustic vowel space metrics that reflect the dynamic contributions of both consonant and vowel segments are sensitive to within-speaker changes in articulation associated with manipulations of speech intensity.

Acoustic emission intrusion detector

DOEpatents

Carver, Donald W.; Whittaker, Jerry W.

1980-01-01

An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal.

Resonant capacitive MEMS acoustic emission transducers

NASA Astrophysics Data System (ADS)

Ozevin, D.; Greve, D. W.; Oppenheim, I. J.; Pessiki, S. P.

2006-12-01

We describe resonant capacitive MEMS transducers developed for use as acoustic emission (AE) detectors, fabricated in the commercial three-layer polysilicon surface micromachining process (MUMPs). The 1 cm square device contains six independent transducers in the frequency range between 100 and 500 kHz, and a seventh transducer at 1 MHz. Each transducer is a parallel plate capacitor with one plate free to vibrate, thereby causing a capacitance change which creates an output signal in the form of a current under a dc bias voltage. With the geometric proportions we employed, each transducer responds with two distinct resonant frequencies. In our design the etch hole spacing was chosen to limit squeeze film damping and thereby produce an underdamped vibration when operated at atmospheric pressure. Characterization experiments obtained by capacitance and admittance measurements are presented, and transducer responses to physically simulated AE source are discussed. Finally, we report our use of the device to detect acoustic emissions associated with crack initiation and growth in weld metal.

Generation of thermo-acoustic waves from pulsed solar/IR radiation

NASA Astrophysics Data System (ADS)

Rahman, Aowabin

Acoustic waves could potentially be used in a wide range of engineering applications; however, the high energy consumption in generating acoustic waves from electrical energy and the cost associated with the process limit the use of acoustic waves in industrial processes. Acoustic waves converted from solar radiation provide a feasible way of obtaining acoustic energy, without relying on conventional nonrenewable energy sources. One of the goals of this thesis project was to experimentally study the conversion of thermal to acoustic energy using pulsed radiation. The experiments were categorized into "indoor" and "outdoor" experiments, each with a separate experimental setup. The indoor experiments used an IR heater to power the thermo-acoustic lasers and were primarily aimed at studying the effect of various experimental parameters on the amplitude of sound waves in the low frequency range (below 130 Hz). The IR radiation was modulated externally using a chopper wheel and then impinged on a porous solid, which was housed inside a thermo-acoustic (TA) converter. A microphone located at a certain distance from the porous solid inside the TA converter detected the acoustic signals. The "outdoor" experiments, which were targeted at TA conversion at comparatively higher frequencies (in 200 Hz-3 kHz range) used solar energy to power the thermo-acoustic laser. The amplitudes (in RMS) of thermo-acoustic signals obtained in experiments using IR heater as radiation source were in the 80-100 dB range. The frequency of acoustic waves corresponded to the frequency of interceptions of the radiation beam by the chopper. The amplitudes of acoustic waves were influenced by several factors, including the chopping frequency, magnitude of radiation flux, type of porous material, length of porous material, external heating of the TA converter housing, location of microphone within the air column, and design of the TA converter. The time-dependent profile of the thermo-acoustic signals

Method and apparatus for using magneto-acoustic remanence to determine embrittlement

NASA Technical Reports Server (NTRS)

Allison, Sidney G. (Inventor); Namkung, Min (Inventor); Yost, William T. (Inventor); Cantrell, John H. (Inventor)

1992-01-01

A method and apparatus for testing steel components for temperature embrittlement uses magneto-acoustic emission to nondestructively evaluate the component are presented. Acoustic emission signals occur more frequently at higher levels in embrittled components. A pair of electromagnets are used to create magnetic induction in the test component. Magneto-acoustic emission signals may be generated by applying an AC current to the electromagnets. The acoustic emission signals are analyzed to provide a comparison between a component known to be unembrittled and a test component. Magnetic remanence is determined by applying a DC current to the electromagnets and then by turning the magnets off and observing the residual magnetic induction.

Dynamic Encoding of Acoustic Features in Neural Responses to Continuous Speech.

PubMed

Khalighinejad, Bahar; Cruzatto da Silva, Guilherme; Mesgarani, Nima

2017-02-22

Humans are unique in their ability to communicate using spoken language. However, it remains unclear how the speech signal is transformed and represented in the brain at different stages of the auditory pathway. In this study, we characterized electroencephalography responses to continuous speech by obtaining the time-locked responses to phoneme instances (phoneme-related potential). We showed that responses to different phoneme categories are organized by phonetic features. We found that each instance of a phoneme in continuous speech produces multiple distinguishable neural responses occurring as early as 50 ms and as late as 400 ms after the phoneme onset. Comparing the patterns of phoneme similarity in the neural responses and the acoustic signals confirms a repetitive appearance of acoustic distinctions of phonemes in the neural data. Analysis of the phonetic and speaker information in neural activations revealed that different time intervals jointly encode the acoustic similarity of both phonetic and speaker categories. These findings provide evidence for a dynamic neural transformation of low-level speech features as they propagate along the auditory pathway, and form an empirical framework to study the representational changes in learning, attention, and speech disorders. SIGNIFICANCE STATEMENT We characterized the properties of evoked neural responses to phoneme instances in continuous speech. We show that each instance of a phoneme in continuous speech produces several observable neural responses at different times occurring as early as 50 ms and as late as 400 ms after the phoneme onset. Each temporal event explicitly encodes the acoustic similarity of phonemes, and linguistic and nonlinguistic information are best represented at different time intervals. Finally, we show a joint encoding of phonetic and speaker information, where the neural representation of speakers is dependent on phoneme category. These findings provide compelling new evidence for

Classifiers utilized to enhance acoustic based sensors to identify round types of artillery/mortar

NASA Astrophysics Data System (ADS)

Grasing, David; Desai, Sachi; Morcos, Amir

2008-04-01

Feature extraction methods based on the statistical analysis of the change in event pressure levels over a period and the level of ambient pressure excitation facilitate the development of a robust classification algorithm. The features reliably discriminates mortar and artillery variants via acoustic signals produced during the launch events. Utilizing acoustic sensors to exploit the sound waveform generated from the blast for the identification of mortar and artillery variants as type A, etcetera through analysis of the waveform. Distinct characteristics arise within the different mortar/artillery variants because varying HE mortar payloads and related charges emphasize varying size events at launch. The waveform holds various harmonic properties distinct to a given mortar/artillery variant that through advanced signal processing and data mining techniques can employed to classify a given type. The skewness and other statistical processing techniques are used to extract the predominant components from the acoustic signatures at ranges exceeding 3000m. Exploiting these techniques will help develop a feature set highly independent of range, providing discrimination based on acoustic elements of the blast wave. Highly reliable discrimination will be achieved with a feedforward neural network classifier trained on a feature space derived from the distribution of statistical coefficients, frequency spectrum, and higher frequency details found within different energy bands. The processes that are described herein extend current technologies, which emphasis acoustic sensor systems to provide such situational awareness.

Acoustic leak-detection system for railroad transportation security

NASA Astrophysics Data System (ADS)

Womble, P. C.; Spadaro, J.; Harrison, M. A.; Barzilov, A.; Harper, D.; Hopper, L.; Houchins, E.; Lemoff, B.; Martin, R.; McGrath, C.; Moore, R.; Novikov, I.; Paschal, J.; Rogers, S.

2007-04-01

Pressurized rail tank cars transport large volumes of volatile liquids and gases throughout the country, much of which is hazardous and/or flammable. These gases, once released in the atmosphere, can wreak havoc with the environment and local populations. We developed a system which can non-intrusively and non-invasively detect and locate pinhole-sized leaks in pressurized rail tank cars using acoustic sensors. The sound waves from a leak are produced by turbulence from the gas leaking to the atmosphere. For example, a 500 μm hole in an air tank pressurized to 689 kPa produces a broad audio frequency spectrum with a peak near 40 kHz. This signal is detectable at 10 meters with a sound pressure level of 25 dB. We are able to locate a leak source using triangulation techniques. The prototype of the system consists of a network of acoustic sensors and is located approximately 10 meters from the center of the rail-line. The prototype has two types of acoustic sensors, each with different narrow frequency response band: 40 kHz and 80 kHz. The prototype is connected to the Internet using WiFi (802.11g) transceiver and can be remotely operated from anywhere in the world. The paper discusses the construction, operation and performance of the system.

Receiver bias and the acoustic ecology of aye-ayes (Daubentonia madagascariensis).

PubMed

Ramsier, Marissa A; Dominy, Nathaniel J

2012-11-01

The aye-aye is a rare lemur from Madagascar that uses its highly specialized middle digit for percussive foraging. This acoustic behavior, also termed tap-scanning, produces dominant frequencies between 6 and 15 kHz. An enhanced auditory sensitivity to these frequencies raises the possibility that the acoustic and auditory specializations of aye-ayes have imposed constraints on the evolution of their vocal signals, especially their primary long-distance vocalization, the screech. Here we explore this concept, termed receiver bias, and suggest that the dominant frequency of the screech call (~2.7 kHz) represents an evolutionary compromise between the opposing adaptive advantages of long-distance sound propagation and enhanced detection by conspecific receivers.

NEMO-SMO acoustic array: A deep-sea test of a novel acoustic positioning system for a km3-scale underwater neutrino telescope

NASA Astrophysics Data System (ADS)

Viola, S.; Ardid, M.; Bertin, V.; Enzenhöfer, A.; Keller, P.; Lahmann, R.; Larosa, G.; Llorens, C. D.; NEMO Collaboration; SMO Collaboration

2013-10-01

Within the activities of the NEMO project, the installation of a 8-floors tower (NEMO-Phase II) at a depth of 3500 m is foreseen in 2012. The tower will be installed about 80 km off-shore Capo Passero, in Sicily. On board the NEMO tower, an array of 18 acoustic sensors will be installed, permitting acoustic detection of biological sources, studies for acoustic neutrino detection and primarily acoustic positioning of the underwater structures. For the latter purpose, the sensors register acoustic signals emitted by five acoustic beacons anchored on the sea-floor. The data acquisition system of the acoustic sensors is fully integrated with the detector data transport system and is based on an “all data to shore” philosophy. Signals coming from hydrophones are continuously sampled underwater at 192 kHz/24 bit and transmitted to shore through an electro-optical cable for real-time analysis. A novel technology for underwater GPS time-stamping of data has been implemented and tested. The operation of the acoustic array will permit long-term test of sensors and electronics technologies that are proposed for the acoustic positioning system of KM3NeT.

Developing a Passive Acoustic Monitoring Network for Harbor Porpoise in California

NASA Astrophysics Data System (ADS)

Jacobson, Eiren Kate

Assessing the abundance of and trends in whale, dolphin, and porpoise (cetacean) populations using traditional visual methods can be challenging due primarily to their limited availability at the surface of the ocean. As a result, researchers are increasingly interested in incorporating non-visual and remote observations to improve cetacean population assessments. Passive acoustic monitoring (PAM) can complement or replace visual surveys for cetaceans that produce echolocation clicks, whistles, and other vocalizations. My doctoral dissertation is focused on developing methods to improve PAM of cetaceans. I used the Monterey Bay population of harbor porpoise (Phocoena phocoena ) as a case study for methods development. In Chapter 2, I used passive acoustic data to document that harbor porpoises avoid bottlenose dolphins (Tursiops truncatus) in nearshore Monterey Bay. In Chapter 3, I investigated whether different passive acoustic instruments could be used to monitor harbor porpoise. I recorded harbor porpoise echolocation clicks simultaneously on two different passive acoustic instruments and compared the number and peak frequency of echolocation signals recorded on the two instruments. I found that the number of echolocation clicks was highly correlated between instruments but that the peak frequency of echolocation clicks was not well-correlated, suggesting that some instruments may not be capable of discriminating harbor porpoise echolocation clicks in regions where multiple species with similar echolocation signals are present. In Chapter 4, I used paired visual and passive acoustic surveys to estimate the effective detection area of the passive acoustic sensors in a Bayesian framework. This approach resulted in a posterior distribution of the effective detection area that was consistent with previously published values. In Chapter 5, I used aerial survey and passive acoustic data in a simulation framework to investigate the statistical power of different

Acoustic microscope surface inspection system and method

DOEpatents

Khuri-Yakub, B.T.; Parent, P.; Reinholdtsen, P.A.

1991-02-26

An acoustic microscope surface inspection system and method are described in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respect to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations. 7 figures.

Refinement and application of acoustic impulse technique to study nozzle transmission characteristics

NASA Technical Reports Server (NTRS)

Salikuddin, M.; Brown, W. H.; Ramakrishnan, R.; Tanna, H. K.

1983-01-01

An improved acoustic impulse technique was developed and was used to study the transmission characteristics of duct/nozzle systems. To accomplish the above objective, various problems associated with the existing spark-discharge impulse technique were first studied. These included (1) the nonlinear behavior of high intensity pulses, (2) the contamination of the signal with flow noise, (3) low signal-to-noise ratio at high exhaust velocities, and (4) the inability to control or shape the signal generated by the source, specially when multiple spark points were used as the source. The first step to resolve these problems was the replacement of the spark-discharge source with electroacoustic driver(s). These included (1) synthesizing on acoustic impulse with acoustic driver(s) to control and shape the output signal, (2) time domain signal averaging to remove flow noise from the contaminated signal, (3) signal editing to remove unwanted portions of the time history, (4) spectral averaging, and (5) numerical smoothing. The acoustic power measurement technique was improved by taking multiple induct measurements and by a modal decomposition process to account for the contribution of higher order modes in the power computation. The improved acoustic impulse technique was then validated by comparing the results derived by an impedance tube method. The mechanism of acoustic power loss, that occurs when sound is transmitted through nozzle terminations, was investigated. Finally, the refined impulse technique was applied to obtain more accurate results for the acoustic transmission characteristics of a conical nozzle and a multi-lobe multi-tube supressor nozzle.

Dual instrument passive acoustic monitoring of belugas in Cook Inlet, Alaska.

PubMed

Castellote, Manuel; Small, Robert J; Lammers, Marc O; Jenniges, Justin J; Mondragon, Jeff; Atkinson, Shannon

2016-05-01

As part of a long-term research program, Cook Inlet beluga (Delphinapterus leucas) presence was acoustically monitored with two types of acoustic sensors utilized in tandem in moorings deployed year-round: an ecological acoustic recorder (EAR) and a cetacean and porpoise detector (C-POD). The EAR was used primarily to record the calls, whistles, and buzzes produced by belugas and killer whales (Orcinus orca). The C-POD was used to log and classify echolocation clicks from belugas, killer whales, and porpoises. This paper describes mooring packages that maximized the chances of successful long-term data collection in the particularly challenging Cook Inlet environment, and presents an analytical comparison of odontocete detections obtained by the collocated EAR and C-POD instruments from two mooring locations in the upper inlet. Results from this study illustrate a significant improvement in detecting beluga and killer whale presence when the different acoustic signals detected by EARs and C-PODs are considered together. Further, results from concurrent porpoise detections indicating prey competition and feeding interference with beluga, and porpoise displacement due to ice formation are described.

Information Theory Filters for Wavelet Packet Coefficient Selection with Application to Corrosion Type Identification from Acoustic Emission Signals

PubMed Central

Van Dijck, Gert; Van Hulle, Marc M.

2011-01-01

The damage caused by corrosion in chemical process installations can lead to unexpected plant shutdowns and the leakage of potentially toxic chemicals into the environment. When subjected to corrosion, structural changes in the material occur, leading to energy releases as acoustic waves. This acoustic activity can in turn be used for corrosion monitoring, and even for predicting the type of corrosion. Here we apply wavelet packet decomposition to extract features from acoustic emission signals. We then use the extracted wavelet packet coefficients for distinguishing between the most important types of corrosion processes in the chemical process industry: uniform corrosion, pitting and stress corrosion cracking. The local discriminant basis selection algorithm can be considered as a standard for the selection of the most discriminative wavelet coefficients. However, it does not take the statistical dependencies between wavelet coefficients into account. We show that, when these dependencies are ignored, a lower accuracy is obtained in predicting the corrosion type. We compare several mutual information filters to take these dependencies into account in order to arrive at a more accurate prediction. PMID:22163921

Digital servo control of random sound test excitation. [in reverberant acoustic chamber

NASA Technical Reports Server (NTRS)

Nakich, R. B. (Inventor)

1974-01-01

A digital servocontrol system for random noise excitation of a test object in a reverberant acoustic chamber employs a plurality of sensors spaced in the sound field to produce signals in separate channels which are decorrelated and averaged. The average signal is divided into a plurality of adjacent frequency bands cyclically sampled by a time division multiplex system, converted into digital form, and compared to a predetermined spectrum value stored in digital form. The results of the comparisons are used to control a time-shared up-down counter to develop gain control signals for the respective frequency bands in the spectrum of random sound energy picked up by the microphones.

An active acoustic tripwire for simultaneous detection and localization of multiple underwater intruders.

PubMed

Folegot, Thomas; Martinelli, Giovanna; Guerrini, Piero; Stevenson, J Mark

2008-11-01

An algorithm allowing simultaneous detection and localization of multiple submerged targets crossing an acoustic tripwire based on forward scattering is described and then evaluated based upon data collected at sea. This paper quantifies the agreement between the theoretical performance and the results obtained from processing data gathered at sea for crossings at several depths and ranges. Targets crossing the acoustic field produce shadows on each side of the barrier, for specific sensors and for specific acoustic paths. In post-processing, a model is invoked to associate expected paths with the observed shadows. This process allows triangulation of the target's position inside the acoustic field. Precise localization is achieved by taking advantage of the multipath propagation structure of the received signal, together with the diversity of the source and receiver locations. Environmental robustness is demonstrated using simulations and can be explained by the use of an array of sources spatially distributed through the water column.

First description of underwater acoustic diversity in three temperate ponds.

PubMed

Desjonquères, Camille; Rybak, Fanny; Depraetere, Marion; Gasc, Amandine; Le Viol, Isabelle; Pavoine, Sandrine; Sueur, Jérôme

2015-01-01

The past decade has produced an increased ecological interest in sonic environments, or soundscapes. However, despite this rise in interest and technological improvements that allow for long-term acoustic surveys in various environments, some habitats' soundscapes remain to be explored. Ponds, and more generally freshwater habitats, are one of these acoustically unexplored environments. Here we undertook the first long term acoustic monitoring of three temperate ponds in France. By aural and visual inspection of a selection of recordings, we identified 48 different sound types, and according to the rarefaction curves we calculated, more sound types are likely present in one of the three ponds. The richness of sound types varied significantly across ponds. Surprisingly, there was no pond-to-pond daily consistency of sound type richness variation; each pond had its own daily patterns of activity. We also explored the possibility of using six acoustic diversity indices to conduct rapid biodiversity assessments in temperate ponds. We found that all indices were sensitive to the background noise as estimated through correlations with the signal-to-noise ratio (SNR). However, we determined that the AR index could be a good candidate to measure acoustic diversities using partial correlations with the SNR as a control variable. Yet, research is still required to automatically compute the SNR in order to apply this index on a large data set of recordings. The results showed that these three temperate ponds host a high level of acoustic diversity in which the soundscapes were variable not only between but also within the ponds. The sources producing this diversity of sounds and the drivers of difference in daily song type richness variation both require further investigation. Such research would yield insights into the biodiversity and ecology of temperate ponds.

Pipe wall damage detection by electromagnetic acoustic transducer generated guided waves in absence of defect signals.

PubMed

Vasiljevic, Milos; Kundu, Tribikram; Grill, Wolfgang; Twerdowski, Evgeny

2008-05-01

Most investigators emphasize the importance of detecting the reflected signal from the defect to determine if the pipe wall has any damage and to predict the damage location. However, often the small signal from the defect is hidden behind the other arriving wave modes and signal noise. To overcome the difficulties associated with the identification of the small defect signal in the time history plots, in this paper the time history is analyzed well after the arrival of the first defect signal, and after different wave modes have propagated multiple times through the pipe. It is shown that the defective pipe can be clearly identified by analyzing these late arriving diffuse ultrasonic signals. Multiple reflections and scattering of the propagating wave modes by the defect and pipe ends do not hamper the defect detection capability; on the contrary, it apparently stabilizes the signal and makes it easier to distinguish the defective pipe from the defect-free pipe. This paper also highlights difficulties associated with the interpretation of the recorded time histories due to mode conversion by the defect. The design of electro-magnetic acoustic transducers used to generate and receive the guided waves in the pipe is briefly described in the paper.

Detection and tracking of drones using advanced acoustic cameras

NASA Astrophysics Data System (ADS)

Busset, Joël.; Perrodin, Florian; Wellig, Peter; Ott, Beat; Heutschi, Kurt; Rühl, Torben; Nussbaumer, Thomas

2015-10-01

Recent events of drones flying over city centers, official buildings and nuclear installations stressed the growing threat of uncontrolled drone proliferation and the lack of real countermeasure. Indeed, detecting and tracking them can be difficult with traditional techniques. A system to acoustically detect and track small moving objects, such as drones or ground robots, using acoustic cameras is presented. The described sensor, is completely passive, and composed of a 120-element microphone array and a video camera. The acoustic imaging algorithm determines in real-time the sound power level coming from all directions, using the phase of the sound signals. A tracking algorithm is then able to follow the sound sources. Additionally, a beamforming algorithm selectively extracts the sound coming from each tracked sound source. This extracted sound signal can be used to identify sound signatures and determine the type of object. The described techniques can detect and track any object that produces noise (engines, propellers, tires, etc). It is a good complementary approach to more traditional techniques such as (i) optical and infrared cameras, for which the object may only represent few pixels and may be hidden by the blooming of a bright background, and (ii) radar or other echo-localization techniques, suffering from the weakness of the echo signal coming back to the sensor. The distance of detection depends on the type (frequency range) and volume of the noise emitted by the object, and on the background noise of the environment. Detection range and resilience to background noise were tested in both, laboratory environments and outdoor conditions. It was determined that drones can be tracked up to 160 to 250 meters, depending on their type. Speech extraction was also experimentally investigated: the speech signal of a person being 80 to 100 meters away can be captured with acceptable speech intelligibility.

Digital seismo-acoustic signal processing aboard a wireless sensor platform

NASA Astrophysics Data System (ADS)

Marcillo, O.; Johnson, J. B.; Lorincz, K.; Werner-Allen, G.; Welsh, M.

2006-12-01

We are developing a low power, low-cost wireless sensor array to conduct real-time signal processing of earthquakes at active volcanoes. The sensor array, which integrates data from both seismic and acoustic sensors, is based on Moteiv TMote Sky wireless sensor nodes (www.moteiv.com). The nodes feature a Texas Instruments MSP430 microcontroller, 48 Kbytes of program memory, 10 Kbytes of static RAM, 1 Mbyte of external flash memory, and a 2.4-GHz Chipcon CC2420 IEEE 802.15.4 radio. The TMote Sky is programmed in TinyOS. Basic signal processing occurs on an array of three peripheral sensor nodes. These nodes are tied into a dedicated GPS receiver node, which is focused on time synchronization, and a central communications node, which handles data integration and additional processing. The sensor nodes incorporate dual 12-bit digitizers sampling a seismic sensor and a pressure transducer at 100 samples per second. The wireless capabilities of the system allow flexible array geometry, with a maximum aperture of 200m. We have already developed the digital signal processing routines on board the Moteiv Tmote sensor nodes. The developed routines accomplish Real-time Seismic-Amplitude Measurement (RSAM), Seismic Spectral- Amplitude Measurement (SSAM), and a user-configured Short Term Averaging / Long Term Averaging (STA LTA ratio), which is used to calculate first arrivals. The processed data from individual nodes are transmitted back to a central node, where additional processing may be performed. Such processing will include back azimuth determination and other wave field analyses. Future on-board signal processing will focus on event characterization utilizing pattern recognition and spectral characterization. The processed data is intended as low bandwidth information which can be transmitted periodically and at low cost through satellite telemetry to a web server. The processing is limited by the computational capabilities (RAM, ROM) of the nodes. Nevertheless, we

High-sensitivity fiber optic acoustic sensors

NASA Astrophysics Data System (ADS)

Lu, Ping; Liu, Deming; Liao, Hao

2016-11-01

Due to the overwhelming advantages compared with traditional electronicsensors, fiber-optic acoustic sensors have arisen enormous interest in multiple disciplines. In this paper we present the recent research achievements of our group on fiber-optic acoustic sensors. The main point of our research is high sensitivity interferometric acoustic sensors, including Michelson, Sagnac, and Fabry-Pérot interferometers. In addition, some advanced technologies have been proposed for acoustic or acoustic pressure sensing such as single-mode/multimode fiber coupler, dual FBGs and multi-longitudinal mode fiber laser based acoustic sensors. Moreover, our attention we have also been paid on signal demodulation schemes. The intensity-based quadrature point (Q-point) demodulation, two-wavelength quadrature demodulation and symmetric 3×3 coupler methodare discussed and compared in this paper.

Applications of surface acoustic and shallow bulk acoustic wave devices

NASA Astrophysics Data System (ADS)

Campbell, Colin K.

1989-10-01

Surface acoustic wave (SAW) device coverage includes delay lines and filters operating at selected frequencies in the range from about 10 MHz to 11 GHz; modeling with single-crystal piezoelectrics and layered structures; resonators and low-loss filters; comb filters and multiplexers; antenna duplexers; harmonic devices; chirp filters for pulse compression; coding with fixed and programmable transversal filters; Barker and quadraphase coding; adaptive filters; acoustic and acoustoelectric convolvers and correlators for radar, spread spectrum, and packet radio; acoustooptic processors for Bragg modulation and spectrum analysis; real-time Fourier-transform and cepstrum processors for radar and sonar; compressive receivers; Nyquist filters for microwave digital radio; clock-recovery filters for fiber communications; fixed-, tunable-, and multimode oscillators and frequency synthesizers; acoustic charge transport; and other SAW devices for signal processing on gallium arsenide. Shallow bulk acoustic wave device applications include gigahertz delay lines, surface-transverse-wave resonators employing energy-trapping gratings, and oscillators with enhanced performance and capability.

Evaluation of a rubber-compound diaphragm for acoustic fisheries surveys: Effects on dual-beam signal intensity and beam patterns

USGS Publications Warehouse

Fleischer, Guy W.; Argyle, R.L.; Nester, R.T.; Dawson, J.J.

2002-01-01

The use of rubber-compound windows for fisheries acoustics must consider operating frequency and ambient water temperatures. Signal attenuation by the rubber becomes pronounced with increased frequency and decreased temperature. Based on our results, a 420 k Hz system could be expected to lose up to 3-4 dB in colder water through a 5.1-cm thick rubber diaphragm. At 120 k Hz, signal loss was negligible and would undoubtedly also be inconsequential for even lower frequencies used in fisheries applications (e.g., 70, 38 k Hz).

Effects of atmospheric variations on acoustic system performance

NASA Technical Reports Server (NTRS)

Nation, Robert; Lang, Stephen; Olsen, Robert; Chintawongvanich, Prasan

1993-01-01

Acoustic propagation over medium to long ranges in the atmosphere is subject to many complex, interacting effects. Of particular interest at this point is modeling low frequency (less than 500 Hz) propagation for the purpose of predicting ranges and bearing accuracies at which acoustic sources can be detected. A simple means of estimating how much of the received signal power propagated directly from the source to the receiver and how much was received by turbulent scattering was developed. The correlations between the propagation mechanism and detection thresholds, beamformer bearing estimation accuracies, and beamformer processing gain of passive acoustic signal detection systems were explored.

Pinniped bioacoustics: Atmospheric and hydrospheric signal production, reception, and function

NASA Astrophysics Data System (ADS)

Schusterman, Ronald J.; Kastak, David; Reichmuth Kastak, Colleen; Holt, Marla; Southall, Brandon L.

2004-05-01

There is no convincing evidence that any of the 33 pinniped species evolved acoustic specializations for echolocation. However, all species produce and localize signals amphibiously in different communicative contexts. In the setting of sexual selection, aquatic mating male phocids and walruses tend to emit underwater calls, while male otariids and phocids that breed terrestrially emit airborne calls. Signature vocalizations are widespread among pinnipeds. There is evidence that males use signature threat calls, and it is possible that vocal recognition may be used by territorial males to form categories consisting of neighbors and strangers. In terms of mother-offspring recognition, both otariid females and their pups use acoustical cues for mutual recognition. In contrast, reunions between phocid females and their dependent pups depend mostly on pup vocalizations. In terms of signal reception, audiometric studies show that otariids are highly sensitive to aerial sounds but slightly less sensitive to underwater sounds. Conversely, except for deep-diving elephant seals, phocids are quite sensitive to acoustic signals both in air and under water. Finally, despite differences in absolute hearing sensitivity, pinnipeds have similar masked hearing capabilities in both media, supporting the notion that cochlear mechanics determine the effects of noise on hearing.

Acoustic method of particle detection and its applications for geophysics studies by means of a neutrino beam. Homage to Prof. B.A. Dolgoshein (1930-2010)

NASA Astrophysics Data System (ADS)

Borissov, A. B.

2013-04-01

Development of the acoustic method of particle detection is presented from the very beginning until current experiments and perspectives. In 1976, Askaryan and Dolgoshein suggested acoustic detection of ultra high energy neutrino in ocean by using an acoustic signal generated according to thermoacoustic mechanism. Practical realization of such project is going on now in several experiments. In 1983, De Rujula, Glashow, Wilson, Charpak presented a possibility to use neutrino beam produced by a multi-TeV proton synchrotron for purposes of geological research. Dedicated studies were started in the group of Dolgoshein. Results of Monte Carlo simulations and measurement of such acoustic signals on the test beams of 70 GeV proton accelerator are reported. A new possibility to forecast the earthquakes using the measurement of the velocity of longitudinal sound waves in the region of earthquake by means of usage of neutrino beam as an underground source of acoustic waves is discussed.

Signals from the deep: Spatial and temporal acoustic occurrence of beaked whales off western Ireland.

PubMed

Kowarski, Katie; Delarue, Julien; Martin, Bruce; O'Brien, Joanne; Meade, Rossa; Ó Cadhla, Oliver; Berrow, Simon

2018-01-01

Little is known of the spatio-temporal occurrence of beaked whales off western Ireland, limiting the ability of Regulators to implement appropriate management and conservation measures. To address this knowledge gap, static acoustic monitoring was carried out using eight fixed bottom-mounted autonomous acoustic recorders: four from May to December 2015 on Ireland's northern slope and four from March to November 2016 on the western and southern slopes. Recorders ran for 205 to 230 days, resulting in 4.09 TB of data sampled at 250 kHz which could capture beaked whale acoustic signals. Zero-crossing-based automated detectors identified beaked whale clicks. A sample of detections was manually validated to evaluate and optimize detector performance. Analysis confirmed the occurrence of Sowerby's and Cuvier's beaked whales and Northern bottlenose whales. Northern bottlenose whale clicks occurred in late summer and autumn, but were too few to allow further analysis. Cuvier's and Sowerby's clicks occurred at all stations throughout the monitoring period. There was a significant effect of month and station (latitude) on the mean daily number of click detections for both species. Cuvier's clicks were more abundant at lower latitudes while Sowerby's were greater at higher latitudes, particularly in the spring, suggesting a spatial segregation between species, possibly driven by prey preference. Cuvier's occurrence increased in late autumn 2015 off northwest Porcupine Bank, a region of higher relative occurrence for each species. Seismic airgun shots, with daily sound exposure levels as high as 175 dB re 1 μPa2·s, did not appear to impact the mean daily number of Cuvier's or Sowerby's beaked whale click detections. This work provides insight into the significance of Irish waters for beaked whales and highlights the importance of using acoustics for beaked whale monitoring.

Plant acoustics: in the search of a sound mechanism for sound signaling in plants.

PubMed

Mishra, Ratnesh Chandra; Ghosh, Ritesh; Bae, Hanhong

2016-08-01

Being sessile, plants continuously deal with their dynamic and complex surroundings, identifying important cues and reacting with appropriate responses. Consequently, the sensitivity of plants has evolved to perceive a myriad of external stimuli, which ultimately ensures their successful survival. Research over past centuries has established that plants respond to environmental factors such as light, temperature, moisture, and mechanical perturbations (e.g. wind, rain, touch, etc.) by suitably modulating their growth and development. However, sound vibrations (SVs) as a stimulus have only started receiving attention relatively recently. SVs have been shown to increase the yields of several crops and strengthen plant immunity against pathogens. These vibrations can also prime the plants so as to make them more tolerant to impending drought. Plants can recognize the chewing sounds of insect larvae and the buzz of a pollinating bee, and respond accordingly. It is thus plausible that SVs may serve as a long-range stimulus that evokes ecologically relevant signaling mechanisms in plants. Studies have suggested that SVs increase the transcription of certain genes, soluble protein content, and support enhanced growth and development in plants. At the cellular level, SVs can change the secondary structure of plasma membrane proteins, affect microfilament rearrangements, produce Ca(2+) signatures, cause increases in protein kinases, protective enzymes, peroxidases, antioxidant enzymes, amylase, H(+)-ATPase / K(+) channel activities, and enhance levels of polyamines, soluble sugars and auxin. In this paper, we propose a signaling model to account for the molecular episodes that SVs induce within the cell, and in so doing we uncover a number of interesting questions that need to be addressed by future research in plant acoustics. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions

Acoustic sand detector for fluid flowstreams

DOEpatents

Beattie, Alan G.; Bohon, W. Mark

1993-01-01

The particle volume and particle mass production rate of particulate solids entrained in fluid flowstreams such as formation sand or fracture proppant entrained in oil and gas production flowstreams is determined by a system having a metal probe interposed in a flow conduit for transmitting acoustic emissions created by particles impacting the probe to a sensor and signal processing circuit which produces discrete signals related to the impact of each of the particles striking the probe. The volume or mass flow rate of particulates is determined from making an initial particle size distribution and particle energy distribution and comparing the initial energy distribution and/or the initial size distribution with values related to the impact energies of a predetermined number of recorded impacts. The comparison is also used to recalibrate the system to compensate for changes in flow velocity.

Underwater acoustic wave generation by filamentation of terawatt ultrashort laser pulses.

PubMed

Jukna, Vytautas; Jarnac, Amélie; Milián, Carles; Brelet, Yohann; Carbonnel, Jérôme; André, Yves-Bernard; Guillermin, Régine; Sessarego, Jean-Pierre; Fattaccioli, Dominique; Mysyrowicz, André; Couairon, Arnaud; Houard, Aurélien

2016-06-01

Acoustic signals generated by filamentation of ultrashort terawatt laser pulses in water are characterized experimentally. Measurements reveal a strong influence of input pulse duration on the shape and intensity of the acoustic wave. Numerical simulations of the laser pulse nonlinear propagation and the subsequent water hydrodynamics and acoustic wave generation show that the strong acoustic emission is related to the mechanism of superfilamention in water. The elongated shape of the plasma volume where energy is deposited drives the far-field profile of the acoustic signal, which takes the form of a radially directed pressure wave with a single oscillation and a very broad spectrum.

Development of an Acoustic Localization Method for Cavitation Experiments in Reverberant Environments

NASA Astrophysics Data System (ADS)

Ranjeva, Minna; Thompson, Lee; Perlitz, Daniel; Bonness, William; Capone, Dean; Elbing, Brian

2011-11-01

Cavitation is a major concern for the US Navy since it can cause ship damage and produce unwanted noise. The ability to precisely locate cavitation onset in laboratory scale experiments is essential for proper design that will minimize this undesired phenomenon. Measuring the cavitation onset is more accurately determined acoustically than visually. However, if other parts of the model begin to cavitate prior to the component of interest the acoustic data is contaminated with spurious noise. Consequently, cavitation onset is widely determined by optically locating the event of interest. The current research effort aims at developing an acoustic localization scheme for reverberant environments such as water tunnels. Currently cavitation bubbles are being induced in a static water tank with a laser, allowing the localization techniques to be refined with the bubble at a known location. The source is located with the use of acoustic data collected with hydrophones and analyzed using signal processing techniques. To verify the accuracy of the acoustic scheme, the events are simultaneously monitored visually with the use of a high speed camera. Once refined testing will be conducted in a water tunnel. This research was sponsored by the Naval Engineering Education Center (NEEC).

Effect of geometric nonlinearity on acoustic modulation

NASA Astrophysics Data System (ADS)

Warnemuende, Kraig; Wu, Hwai-Chung

2005-05-01

Non-linear nondestructive testing is different from linear acoustic in that it correlates the presence and characteristics of a defect with acoustical signals whose frequencies differ from the frequencies of the emitted probe signal. The difference in frequencies between the probe signal and the resulting frequencies is due to a nonlinear transformation of the probe signal as it passes through a defect. Under acoustic interrogation due to longitudinal waves, as the compression phase passes the defect the two sides of the interface are in direct contact and the contact area increases. Similarly, the tensile phase passes through the defect, the two sides separate and the contact area decreases, thereby modulating the signal amplitude. The contact area depends on the roughness of the surface and on the magnitude of the cohesive forces that arise from the small crack openings. Such cohesive forces may be attributed to aggregate interlock (in plain concrete), fiber bridging (in fiber reinforced concrete) or both. In this paper, the frequency shifts of the probe elastic wave will be analytically related to the roughness and varying cohesive forces of the crack-like defect.

Nondestructive online testing method for friction stir welding using acoustic emission

NASA Astrophysics Data System (ADS)

Levikhina, Anastasiya

2017-12-01

The paper reviews the possibility of applying the method of acoustic emission for online monitoring of the friction stir welding process. It is shown that acoustic emission allows the detection of weld defects and their location in real time. The energy of an acoustic signal and the median frequency are suggested to be used as informative parameters. The method of calculating the median frequency with the use of a short time Fourier transform is applied for the identification of correlations between the defective weld structure and properties of the acoustic emission signals received during welding.

Acoustic Full Waveform Inversion to Characterize Near-surface Chemical Explosions

NASA Astrophysics Data System (ADS)

Kim, K.; Rodgers, A. J.

2015-12-01

Recent high-quality, atmospheric overpressure data from chemical high-explosive experiments provide a unique opportunity to characterize near-surface explosions, specifically estimating yield and source time function. Typically, yield is estimated from measured signal features, such as peak pressure, impulse, duration and/or arrival time of acoustic signals. However, the application of full waveform inversion to acoustic signals for yield estimation has not been fully explored. In this study, we apply a full waveform inversion method to local overpressure data to extract accurate pressure-time histories of acoustics sources during chemical explosions. A robust and accurate inversion technique for acoustic source is investigated using numerical Green's functions that take into account atmospheric and topographic propagation effects. The inverted pressure-time history represents the pressure fluctuation at the source region associated with the explosion, and thus, provides a valuable information about acoustic source mechanisms and characteristics in greater detail. We compare acoustic source properties (i.e., peak overpressure, duration, and non-isotropic shape) of a series of explosions having different emplacement conditions and investigate the relationship of the acoustic sources to the yields of explosions. The time histories of acoustic sources may refine our knowledge of sound-generation mechanisms of shallow explosions, and thereby allow for accurate yield estimation based on acoustic measurements. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Apparatus for separating particles utilizing engineered acoustic contrast capture particles

DOEpatents

Kaduchak, Gregory; Ward, Michael D

2014-10-21

An apparatus for separating particles from a medium includes a capillary defining a flow path therein that is in fluid communication with a medium source. The medium source includes engineered acoustic contrast capture particle having a predetermined acoustic contrast. The apparatus includes a vibration generator that is operable to produce at least one acoustic field within the flow path. The acoustic field produces a force potential minima for positive acoustic contrast particles and a force potential minima for negative acoustic contrast particles in the flow path and drives the engineered acoustic contrast capture particles to either the force potential minima for positive acoustic contrast particles or the force potential minima for negative acoustic contrast particles.

Apparatus for separating particles utilizing engineered acoustic contrast capture particles

DOEpatents

Kaduchak, Gregory [Los Alamos, NM; Ward, Michael D [Los Alamos, NM

2011-12-27

An apparatus for separating particles from a medium includes a capillary defining a flow path therein that is in fluid communication with a medium source. The medium source includes engineered acoustic contrast capture particle having a predetermined acoustic contrast. The apparatus includes a vibration generator that is operable to produce at least one acoustic field within the flow path. The acoustic field produces a force potential minima for positive acoustic contrast particles and a force potential minima for negative acoustic contrast particles in the flow path and drives the engineered acoustic contrast capture particles to either the force potential minima for positive acoustic contrast particles or the force potential minima for negative acoustic contrast particles.

Rotation Control In A Cylindrical Acoustic Levitator

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Allen, J. L.

1988-01-01

Second driver introduces net circulation around levitated sample. Two transducers produce two sets of equal counterrotating acoustic fields. By appropriate adjustment of amplitudes and phases in two transducers, total acoustic field made to consist of two unequal counterrotating fields, producing net torque on levitated sample.

Biomechanical monitoring of healing bone based on acoustic emission technology.

PubMed

Hirasawa, Yasusuke; Takai, Shinro; Kim, Wook-Cheol; Takenaka, Nobuyuki; Yoshino, Nobuyuki; Watanabe, Yoshinobu

2002-09-01

Acoustic emission testing is a well-established method for assessment of the mechanical integrity of general construction projects. The purpose of the current study was to investigate the usefulness of acoustic emission technology in monitoring the yield strength of healing callus during external fixation. Thirty-five patients with 39 long bones treated with external fixation were evaluated for fracture healing by monitoring load for the initiation of acoustic emission signal (yield strength) under axial loading. The major criteria for functional bone union based on acoustic emission testing were (1) no acoustic emission signal on full weightbearing, and (2) a higher estimated strength than body weight. The yield strength monitored by acoustic emission testing increased with the time of healing. The external fixator could be removed safely and successfully in 97% of the patients. Thus, the acoustic emission method has good potential as a reliable method for monitoring the mechanical status of healing bone.

Modeling the complexity of acoustic emission during intermittent plastic deformation: Power laws and multifractal spectra

NASA Astrophysics Data System (ADS)

Kumar, Jagadish; Ananthakrishna, G.

2018-01-01

Scale-invariant power-law distributions for acoustic emission signals are ubiquitous in several plastically deforming materials. However, power-law distributions for acoustic emission energies are reported in distinctly different plastically deforming situations such as hcp and fcc single and polycrystalline samples exhibiting smooth stress-strain curves and in dilute metallic alloys exhibiting discontinuous flow. This is surprising since the underlying dislocation mechanisms in these two types of deformations are very different. So far, there have been no models that predict the power-law statistics for discontinuous flow. Furthermore, the statistics of the acoustic emission signals in jerky flow is even more complex, requiring multifractal measures for a proper characterization. There has been no model that explains the complex statistics either. Here we address the problem of statistical characterization of the acoustic emission signals associated with the three types of the Portevin-Le Chatelier bands. Following our recently proposed general framework for calculating acoustic emission, we set up a wave equation for the elastic degrees of freedom with a plastic strain rate as a source term. The energy dissipated during acoustic emission is represented by the Rayleigh-dissipation function. Using the plastic strain rate obtained from the Ananthakrishna model for the Portevin-Le Chatelier effect, we compute the acoustic emission signals associated with the three Portevin-Le Chatelier bands and the Lüders-like band. The so-calculated acoustic emission signals are used for further statistical characterization. Our results show that the model predicts power-law statistics for all the acoustic emission signals associated with the three types of Portevin-Le Chatelier bands with the exponent values increasing with increasing strain rate. The calculated multifractal spectra corresponding to the acoustic emission signals associated with the three band types have a maximum

Modeling the complexity of acoustic emission during intermittent plastic deformation: Power laws and multifractal spectra.

PubMed

Kumar, Jagadish; Ananthakrishna, G

2018-01-01

Scale-invariant power-law distributions for acoustic emission signals are ubiquitous in several plastically deforming materials. However, power-law distributions for acoustic emission energies are reported in distinctly different plastically deforming situations such as hcp and fcc single and polycrystalline samples exhibiting smooth stress-strain curves and in dilute metallic alloys exhibiting discontinuous flow. This is surprising since the underlying dislocation mechanisms in these two types of deformations are very different. So far, there have been no models that predict the power-law statistics for discontinuous flow. Furthermore, the statistics of the acoustic emission signals in jerky flow is even more complex, requiring multifractal measures for a proper characterization. There has been no model that explains the complex statistics either. Here we address the problem of statistical characterization of the acoustic emission signals associated with the three types of the Portevin-Le Chatelier bands. Following our recently proposed general framework for calculating acoustic emission, we set up a wave equation for the elastic degrees of freedom with a plastic strain rate as a source term. The energy dissipated during acoustic emission is represented by the Rayleigh-dissipation function. Using the plastic strain rate obtained from the Ananthakrishna model for the Portevin-Le Chatelier effect, we compute the acoustic emission signals associated with the three Portevin-Le Chatelier bands and the Lüders-like band. The so-calculated acoustic emission signals are used for further statistical characterization. Our results show that the model predicts power-law statistics for all the acoustic emission signals associated with the three types of Portevin-Le Chatelier bands with the exponent values increasing with increasing strain rate. The calculated multifractal spectra corresponding to the acoustic emission signals associated with the three band types have a maximum

Application of an Aligned and Unaligned Signal Processing Technique to Investigate Tones and Broadband Noise in Fan and Contra-Rotating Open Rotor Acoustic Spectra

NASA Technical Reports Server (NTRS)

Miles, Jeffrey Hilton; Hultgren, Lennart S.

2015-01-01

The study of noise from a two-shaft contra-rotating open rotor (CROR) is challenging since the shafts are not phase locked in most cases. Consequently, phase averaging of the acoustic data keyed to a single shaft rotation speed is not meaningful. An unaligned spectrum procedure that was developed to estimate a signal coherence threshold and reveal concealed spectral lines in turbofan engine combustion noise is applied to fan and CROR acoustic data in this paper.

Spontaneous assembly of chemically encoded two-dimensional coacervate droplet arrays by acoustic wave patterning

PubMed Central

Tian, Liangfei; Martin, Nicolas; Bassindale, Philip G.; Patil, Avinash J.; Li, Mei; Barnes, Adrian; Drinkwater, Bruce W.; Mann, Stephen

2016-01-01

The spontaneous assembly of chemically encoded, molecularly crowded, water-rich micro-droplets into periodic defect-free two-dimensional arrays is achieved in aqueous media by a combination of an acoustic standing wave pressure field and in situ complex coacervation. Acoustically mediated coalescence of primary droplets generates single-droplet per node micro-arrays that exhibit variable surface-attachment properties, spontaneously uptake dyes, enzymes and particles, and display spatial and time-dependent fluorescence outputs when exposed to a reactant diffusion gradient. In addition, coacervate droplet arrays exhibiting dynamical behaviour and exchange of matter are prepared by inhibiting coalescence to produce acoustically trapped lattices of droplet clusters that display fast and reversible changes in shape and spatial configuration in direct response to modulations in the acoustic frequencies and fields. Our results offer a novel route to the design and construction of ‘water-in-water' micro-droplet arrays with controllable spatial organization, programmable signalling pathways and higher order collective behaviour. PMID:27708286

The Simplest Demonstration on Acoustic Beats

ERIC Educational Resources Information Center

Ganci, Alessio; Ganci, Salvatore

2015-01-01

The classical demonstration experiment on acoustic beats using two signal generators and a dual trace oscilloscope is an important ingredient in teaching the subject. This short laboratory note aims to point out what may be the simplest demonstrative experiment on acoustic beats to carry out in a classroom without employing any lab apparatus.

Education in acoustics in Argentina

NASA Astrophysics Data System (ADS)

Miyara, Federico

2002-11-01

Over the last decades, education in acoustics (EA) in Argentina has experienced ups and downs due to economic and political issues interfering with long term projects. Unlike other countries, like Chile, where EA has reached maturity in spite of the acoustical industry having shown little development, Argentina has several well-established manufacturers of acoustic materials and equipment but no specific career with a major in acoustics. At the university level, acoustics is taught as a complementary--often elective--course for careers such as architecture, communication engineering, or music. In spite of this there are several research centers with programs covering environmental and community noise, effects of noise on man, acoustic signal processing, musical acoustics and acoustic emission, and several national and international meetings are held each year in which results are communicated and discussed. Several books on a variety of topics such as sound system, architectural acoustics, and noise control have been published as well. Another chapter in EA is technical and vocational education, ranging between secondary and postsecondary levels, with technical training on sound system operation or design. Over the last years there have been several attempts to implement master degrees in acoustics or audio engineering, with little or no success.

Method and system for generating a beam of acoustic energy from a borehole, and applications thereof

DOEpatents

Johnson, Paul A [Santa Fe, NM; Ten Cate, James A [Los Alamos, NM; Guyer, Robert [Reno, NV; Le Bas, Pierre-Yves [Los Alamos, NM; Vu, Cung [Houston, TX; Nihei, Kurt [Oakland, CA; Schmitt, Denis P [Katy, TX; Skelt, Christopher [Houston, TX

2012-02-14

A compact array of transducers is employed as a downhole instrument for acoustic investigation of the surrounding rock formation. The array is operable to generate simultaneously a first acoustic beam signal at a first frequency and a second acoustic beam signal at a second frequency different than the first frequency. These two signals can be oriented through an azimuthal rotation of the array and an inclination rotation using control of the relative phases of the signals from the transmitter elements or electromechanical linkage. Due to the non-linearity of the formation, the first and the second acoustic beam signal mix into the rock formation where they combine into a collimated third signal that propagates in the formation along the same direction than the first and second signals and has a frequency equal to the difference of the first and the second acoustic signals. The third signal is received either within the same borehole, after reflection, or another borehole, after transmission, and analyzed to determine information about rock formation. Recording of the third signal generated along several azimuthal and inclination directions also provides 3D images of the formation, information about 3D distribution of rock formation and fluid properties and an indication of the dynamic acoustic non-linearity of the formation.

Infrasound signal detection and characterization using ground-coupled airwaves on a single seismo-acoustic sensor pair

NASA Astrophysics Data System (ADS)

McKee, K. F.; Fee, D.; Haney, M. M.; Lyons, J. J.; Matoza, R. S.

2016-12-01

A ground-coupled airwave (GCA) occurs when an incident atmospheric pressure wave encounters the Earth's surface and part of the energy of the wave is transferred to the ground (i.e. coupled to the ground) as a seismic wave. This seismic wave propagates as a surface Rayleigh wave evidenced by the retrograde particle motion detected on a three-component seismometer. Acoustic waves recorded on a collocated microphone and seismometer can be coherent and have a 90-degree phase difference, predicted by theory and in agreement with observations. If the sensors are separated relative to the frequencies of interest, usually 10s to 100s of meters, then recorded wind noise becomes incoherent and an additional phase shift is present due to the separation distance. These characteristics of GCAs have been used to distinguish wind noise from other sources as well as to determine the acoustic contribution to seismic recordings. Here we aim to develop a minimalist infrasound signal detection and characterization technique requiring just one microphone and one three-component seismometer. Based on GCA theory, determining a source azimuth should be possible using a single seismo-acoustic sensor pair by utilizing the phase difference and exploiting the characteristic particle motion. We will use synthetic seismo-acoustic data generated by a coupled Earth-atmosphere 3D finite difference code to test and tune the detection and characterization method. The method will then be further tested using various well-constrained sources (e.g. Chelyabinsk meteor, Pagan Volcano, Cleveland Volcano). Such a technique would be advantageous in situations where resources are limited and large sensor networks are not feasible.

Differences in acoustic features of vocalizations produced by killer whales cross-socialized with bottlenose dolphins.

PubMed

Musser, Whitney B; Bowles, Ann E; Grebner, Dawn M; Crance, Jessica L

2014-10-01

Limited previous evidence suggests that killer whales (Orcinus orca) are capable of vocal production learning. However, vocal contextual learning has not been studied, nor the factors promoting learning. Vocalizations were collected from three killer whales with a history of exposure to bottlenose dolphins (Tursiops truncatus) and compared with data from seven killer whales held with conspecifics and nine bottlenose dolphins. The three whales' repertoires were distinguishable by a higher proportion of click trains and whistles. Time-domain features of click trains were intermediate between those of whales held with conspecifics and dolphins. These differences provided evidence for contextual learning. One killer whale spontaneously learned to produce artificial chirps taught to dolphins; acoustic features fell within the range of inter-individual differences among the dolphins. This whale also produced whistles similar to a stereotyped whistle produced by one dolphin. Thus, results provide further support for vocal production learning and show that killer whales are capable of contextual learning. That killer whales produce similar repertoires when associated with another species suggests substantial vocal plasticity and motivation for vocal conformity with social associates.

Robust analysis method for acoustic properties of biological specimens measured by acoustic microscopy

NASA Astrophysics Data System (ADS)

Arakawa, Mototaka; Mori, Shohei; Kanai, Hiroshi; Nagaoka, Ryo; Horie, Miki; Kobayashi, Kazuto; Saijo, Yoshifumi

2018-07-01

We proposed a robust analysis method for the acoustic properties of biological specimens measured by acoustic microscopy. Reflected pulse signals from the substrate and specimen were converted into frequency domains to obtain sound speed and thickness. To obtain the average acoustic properties of the specimen, parabolic approximation was performed to determine the frequency at which the amplitude of the normalized spectrum became maximum or minimum, considering the sound speed and thickness of the specimens and the operating frequency of the ultrasonic device used. The proposed method was demonstrated for a specimen of malignant melanoma of the skin by using acoustic microscopy attaching a concave transducer with a center frequency of 80 MHz. The variations in sound speed and thickness analyzed by the proposed method were markedly smaller than those analyzed by the method based on an autoregressive model. The proposed method is useful for the analysis of the acoustic properties of bilogical tissues or cells.

Acoustic characteristics of Punjabi retroflex and dental stops.

PubMed

Hussain, Qandeel; Proctor, Michael; Harvey, Mark; Demuth, Katherine

2017-06-01

The phonological category "retroflex" is found in many Indo-Aryan languages; however, it has not been clearly established which acoustic characteristics reliably differentiate retroflexes from other coronals. This study investigates the acoustic phonetic properties of Punjabi retroflex /ʈ/ and dental /ʈ̪/ in word-medial and word-initial contexts across /i e a o u/, and in word-final context across /i a u/. Formant transitions, closure and release durations, and spectral moments of release bursts are compared in 2280 stop tokens produced by 30 speakers. Although burst spectral measures and formant transitions do not consistently differentiate retroflexes from dentals in some vowel contexts, stop release duration, and total stop duration reliably differentiate Punjabi retroflex and dental stops across all word contexts and vocalic environments. These results suggest that Punjabi coronal place contrasts are signaled by the complex interaction of temporal and spectral cues.

Wireless acoustic-electric feed-through for power and signal transmission

NASA Technical Reports Server (NTRS)

Doty, Benjamin (Inventor); Badescu, Mircea (Inventor); Sherrit, Stewart (Inventor); Bao, Xiaoqi (Inventor); Bar-Cohen, Yoseph (Inventor); Chang, Zensheu (Inventor)

2011-01-01

An embodiment provides electrical energy from a source on one side of a medium to a load on the other side of the medium, the embodiment including a first piezoelectric to generate acoustic energy in response to electrical energy from the source, and a second piezoelectric to convert the received acoustic energy to electrical energy used by the load. Other embodiments are described and claimed.

Controlling Sample Rotation in Acoustic Levitation

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Stoneburner, J. D.

1985-01-01

Rotation of acoustically levitated object stopped or controlled according to phase-shift monitoring and control concept. Principle applies to square-cross-section levitation chamber with two perpendicular acoustic drivers operating at same frequency. Phase difference between X and Y acoustic excitation measured at one corner by measuring variation of acoustic amplitude sensed by microphone. Phase of driver adjusted to value that produces no rotation or controlled rotation of levitated object.

Coherent entropy induced and acoustic noise separation in compact nozzles

NASA Astrophysics Data System (ADS)

Tao, Wenjie; Schuller, Thierry; Huet, Maxime; Richecoeur, Franck

2017-04-01

A method to separate entropy induced noise from an acoustic pressure wave in an harmonically perturbed flow through a nozzle is presented. It is tested on an original experimental setup generating simultaneously acoustic and temperature fluctuations in an air flow that is accelerated by a convergent nozzle. The setup mimics the direct and indirect noise contributions to the acoustic pressure field in a confined combustion chamber by producing synchronized acoustic and temperature fluctuations, without dealing with the complexity of the combustion process. It allows generating temperature fluctuations with amplitude up to 10 K in the frequency range from 10 to 100 Hz. The noise separation technique uses experiments with and without temperature fluctuations to determine the relative level of acoustic and entropy fluctuations in the system and to identify the nozzle response to these forcing waves. It requires multi-point measurements of acoustic pressure and temperature. The separation method is first validated with direct numerical simulations of the nonlinear Euler equations. These simulations are used to investigate the conditions for which the separation technique is valid and yield similar trends as the experiments for the investigated flow operating conditions. The separation method then gives successfully the acoustic reflection coefficient but does not recover the same entropy reflection coefficient as predicted by the compact nozzle theory due to the sensitivity of the method to signal noises in the explored experimental conditions. This methodology provides a framework for experimental investigation of direct and indirect combustion noises originating from synchronized perturbations.

Apparatus for separating particles utilizing engineered acoustic contrast capture particles

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

Kaduchak, Gregory; Ward, Michael D