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Journal of the Acoustical Society of America

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Jan 2010

Volume 127, Issue 1, pp. EL1-611

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Voice fundamental frequency modulates vocal response to pitch perturbations during English speech

Hanjun Liu, James Auger, and Charles R. Larson

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. EL1-EL5 (2009); (5 pages) | Cited 3 times

Online Publication Date: 15 Dec 2009

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Previous research has demonstrated task-dependent vocal responses to pitch perturbations during speech production. The present study investigated the effect of voice fundamental frequency (F0) on the modulation of vocal responses during English speech. Randomized pitch shifts of ±100 or 200 cents during speaking were presented to English speakers. Results indicated larger vocal responses and shorter latencies at a high voice F0 than at a low voice F0, but no significance differences were observed for stimulus magnitude or direction. These findings suggest that the pitch-shift reflex during speech can be modulated as a function of voice F0.
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43.70.Aj Anatomy and physiology of the vocal tract, speech aerodynamics, auditory kinetics
43.70.Bk Models and theories of speech production
43.72.Ar Speech analysis and analysis techniques; parametric representation of speech
43.70.Jt Instrumentation and methodology for speech production research
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A method for finding constrictions in high front vowels

Michel T.-T. Jackson and Richard S. McGowan

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. EL6-EL12 (2009); (7 pages) | Cited 1 time

Online Publication Date: 15 Dec 2009

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The purpose of this study was to devise a consistent and robust method for defining vocal tract constrictions in high front vowels. A procedure was devised to find the length and position of the articulatory constriction in high front vowels that is not sensitive to local fluctuations in vocal tract shape and to the constriction-defining parameters. A method based on a visual examination of plots for constriction length and position as functions of the constriction-defining parameters was found to provide stable constriction definitions.
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43.70.Bk Models and theories of speech production
43.70.Kv Cross-linguistic speech production and acoustics
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Multiple instances of vocal sensorimotor adaptation to frequency-altered feedback within a single experimental session

Colin S. Hawco and Jeffery A. Jones

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. EL13-EL18 (2009); (6 pages)

Online Publication Date: 16 Dec 2009

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Vocal sensory-motor adaptation is typically studied by introducing a prolonged change in auditory feedback. While it may be preferable to perform multiple blocks of adaptation within a single experiment, it is possible that a carry-over effect from previous blocks of adaptation may affect the results of subsequent blocks. Speakers were asked to vocalize an /a/ sound and match a target note during ten adaptation blocks. Each block represented a unique combination of target note and shift direction. The adaptation response was found to be similar for all blocks, indicating that there were no carry-over effects from previous blocks of adaptation.
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43.70.Mn Relations between speech production and perception
43.70.Bk Models and theories of speech production
43.72.Ar Speech analysis and analysis techniques; parametric representation of speech
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Post-transient shifts in auditory lateralization: Effects of target level

Yoav Arieh and Lawrence E. Marks

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 1-4 (2010); (4 pages)

Online Publication Date: 05 Jan 2010

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Exposing one ear to a series of brief 80 dB sound pressure level (SPL) inducing tones reduces the tendency to lateralize subsequent target tones to that ear and shifts the point of subjective equality (PSE) toward the unexposed ear. Furthermore, targets with average SPLs of 60 and 80 dB at the two ears showed similar changes in PSE. These results support and extend earlier findings of Arieh and Marks (2007). Percept. Psychophys. 69, 523–528 and suggest the presence of a mechanism, located at least partially before the site of binaural integration, that depresses the magnitude of intensity information from the ear in response to moderately intense transient stimuli. Assuming that lateralization depends on the ratio of the magnitude of intensity information from the two ears that reach the central integrator, the results imply that the inducer reduced the representations of magnitude of 60 and 80 dB test tones in equal proportion.
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43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Cb Loudness, absolute threshold
43.66.Pn Binaural hearing
43.66.Qp Localization of sound sources

The role of temporal fine structure in harmonic segregation through mistuning

Brian C. J. Moore and Brian R. Glasberg

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 5-8 (2010); (4 pages) | Cited 3 times

Online Publication Date: 05 Jan 2010

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Bernstein and Oxenham [ (2008). J. Acoust. Soc. Am. 124, 1653–1667 ] measured thresholds for discriminating the fundamental frequency, F0, of a complex tone that was passed through a fixed bandpass filter. They found that performance worsened when the F0 was decreased so that only harmonics above the tenth were audible. However, performance in this case was improved by mistuning the odd harmonics by 3%. Bernstein and Oxenham considered whether the results could be explained in terms of temporal fine structure information available at the output of a single auditory filter and concluded that their results did not appear to be consistent with such an explanation. Here, it is argued that such cues could have led to the improvement in performance produced by mistuning the odd harmonics.
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43.66.Hg Pitch
43.66.Fe Discrimination: intensity and frequency
43.66.Ba Models and theories of auditory processes

The effect of hearing-aid compression on judgments of relative distance

Michael A. Akeroyd

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 9-12 (2010); (4 pages) | Cited 1 time

Online Publication Date: 05 Jan 2010

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The overall level of a sound is an important auditory cue to distance in rooms, but this cue might be affected adversely by the amplitude compression found in most modern hearing aids because this explicitly changes levels. This prediction was tested using a synthetic-distance design to measure the just-noticeable difference (JND) in distance from distances of 2 or 5 m. Twenty-six aided listeners participated. The results did not show any effect of compression ratio upon JNDs. A possible interpretation is that the listeners had acclimatized to the effect their aids have on level.
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43.66.Ts Auditory prostheses, hearing aids
43.66.Sr Deafness, audiometry, aging effects
43.66.Pn Binaural hearing
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Seismoelectric reflection and transmission at a fluid/porous-medium interface

Menne Schakel and David Smeulders

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 13-21 (2010); (9 pages) | Cited 6 times

Online Publication Date: 05 Jan 2010

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The dispersion relation for seismoelectric wave propagation in poroelastic media is formulated in terms of effective densities comprising all viscous and electrokinetic coupling effects. Using Helmholtz decomposition, two seismoelectric conversion coefficients are derived, for an incident P-wave upon an interface between a compressible fluid and a poroelastic medium. These coefficients relate the incident P-wave to a reflected electromagnetic wave in the fluid, and a transmitted electromagnetic wave in the porous medium. The dependency on angle of incidence and frequency is computed. Using orthodox and interference fluxes, it is shown that energy conservation is satisfied. A sensitivity analysis indicates that electrolyte concentration, viscosity, and permeability highly influence seismoelectric conversion.
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43.20.El Reflection, refraction, diffraction of acoustic waves
43.20.Gp Reflection, refraction, diffraction, interference, and scattering of elastic and poroelastic waves
43.40.Ph Seismology and geophysical prospecting; seismographs
43.30.Ma Acoustics of sediments; ice covers, viscoelastic media; seismic underwater acoustics

On Dowell’s simplification for acoustic cavity-structure interaction and consistent alternatives

Jerry H. Ginsberg

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 22-32 (2010); (11 pages) | Cited 6 times

Online Publication Date: 05 Jan 2010

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A widely employed description of the acoustical response in a cavity whose walls are compliant, which was first proposed by Dowell and Voss [(1962). AIAA J. 1, 476–477] , uses the modes of the corresponding cavity with rigid walls as basis functions for a series representation of the pressure. It yields a velocity field that is not compatible with the movement of the boundary, and the system equations do not satisfy the principle of reciprocity. The simplified formulation is compared to consistent solutions of the coupled field equations in the time and frequency domains. In addition, this paper introduces an extension of the Ritz series method to fluid-structure coupled systems that satisfies all continuity conditions by imposing constraint equations to enforce any such conditions that are not identically satisfied by the series. A slender waveguide terminated by an oscillator is analyzed by each method. The simplified formulation is found to be very accurate for light fluid loading, except for the pressure field at frequencies below the fundamental rigid-cavity resonance, whereas the Ritz series solution is found to be extremely accurate in all cases.
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43.20.Tb Interaction of vibrating structures with surrounding medium
43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
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An iterative method for the computation of nonlinear, wide-angle, pulsed acoustic fields of medical diagnostic transducers

J. Huijssen and M. D. Verweij

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 33-44 (2010); (12 pages) | Cited 6 times

Online Publication Date: 05 Jan 2010

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The development and optimization of medical ultrasound transducers and imaging modalities require a computational method that accurately predicts the nonlinear acoustic pressure field. A prospective method should provide the wide-angle, pulsed field emitted by an arbitrary planar source distribution and propagating in a three-dimensional, large scale domain holding a nonlinear acoustic medium. In this paper, a method is presented that is free of any assumed wavefield directionality. The nonlinear acoustic wave equation is solved by treating the nonlinear term as a contrast source. This formulation leads to an iterative scheme that involves the repetitive solution of a linear wave problem through Green’s function method. It is shown that accurate field predictions may be obtained within a few iterations. Moreover, by employing a dedicated numerical convolution technique, the method allows for a discretization down to two points per wavelength or period of the highest frequency of interest. The performance of the method is evaluated through a number of nonlinear field predictions for pulsed transducers with various geometries. The results demonstrate the directional independence of the method. Moreover, comparison with results from several existing methods shows that the method accurately predicts the nonlinear field for weak to moderate nonlinearity.
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43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves
43.80.Qf Medical diagnosis with acoustics

Dislodgement and removal of dust-particles from a surface by a technique combining acoustic standing wave and airflow

Di Chen and Junru Wu

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 45-50 (2010); (6 pages) | Cited 4 times

Online Publication Date: 05 Jan 2010

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It is known that there are many fine particles on the moon and Mars. Their existence may cause risk for the success of a long-term project for NASA, i.e., exploration and habitation of the moon and Mars. These dust-particles might cover the solar panels, making them fail to generate electricity, and they might also penetrate through seals on space suits, hatches, and vehicle wheels causing many incidents. The fine particles would be hazardous to human health if they were inhaled. Development of robust dust mitigation technology is urgently needed for the viable long-term exploration and habilitation of either the moon or Mars. A feasibility study to develop a dust removal technique, which may be used in space-stations or other enclosures for habitation, is reported. It is shown experimentally that the acoustic radiation force produced by a 13.8 kHz 128 dB sound-level standing wave between a 3 cm-aperture tweeter and a reflector separated by 9 cm is strong enough to overcome the van der Waals adhesive force between the dust-particles and the reflector-surface. Thus the majority of fine particles (>2 μm diameter) on a reflector-surface can be dislodged and removed by a technique combining acoustic levitation and airflow methods. The removal efficiency deteriorates for particles of less than 2 μm in size.
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43.25.Uv Acoustic levitation
43.25.Gf Standing waves; resonance

Finite amplitude method for measuring the nonlinearity parameter B/A in small-volume samples using focused ultrasound

Shigemi Saito

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 51-61 (2010); (11 pages) | Cited 2 times

Online Publication Date: 05 Jan 2010

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On the basis of finite amplitude and comparative methods, the acoustic nonlinearity parameter B/A of a liquid sample of as small as 0.1 ml is measured using an 18.6-MHz focused Gaussian beam. The sample fills the space between a polystyrene plate and a tungsten reflector set about 1 mm apart from each other within the focal region. The sound speed c and attenuation coefficient α are determined using the time of flight and the insertion loss of the sound passing through the sample, respectively. The density ρ is estimated from the reflection coefficient at the interface between the polystyrene plate and the sample, where the transformation from longitudinal to transverse waves is considered. To compensate for the effect of velocity dispersion on the second harmonic generation, the relative phase of the second harmonic sound is also measured using dual-frequency sound. By summarizing all the linear properties and amplitude data of the second harmonic component in the sound transmitted through the sample, the B/A value is finally determined. The measurement is validated through the experiments on nondispersive liquids and weakly dispersive biological samples with known B/A values.
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43.25.Zx Measurement methods and instrumentation for nonlinear acoustics
43.25.Ba Parameters of nonlinearity of the medium
43.80.Ev Acoustical measurement methods in biological systems and media
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
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Effective fractional acoustic wave equations in one-dimensional random multiscale media

Josselin Garnier and Knut Sølna

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 62-72 (2010); (11 pages) | Cited 3 times

Online Publication Date: 05 Jan 2010

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This paper considers multiple scattering of waves propagating in a non-lossy one-dimensional random medium with short- or long-range correlations. Using stochastic homogenization theory it is possible to show that pulse propagation is described by an effective deterministic fractional wave equation, which corresponds to an effective medium with a frequency-dependent attenuation that obeys a power law with an exponent between 0 and 2. The exponent is related to the Hurst parameter of the medium, which is a characteristic parameter of the correlation properties of the fluctuations of the random medium. Moreover the frequency-dependent attenuation is associated with a special frequency-dependent phase, which ensures that causality and Kramers–Kronig relations are satisfied. In the time domain the effective wave equation has the form of a linear integro-differential equation with a fractional derivative.
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43.28.Lv Statistical characteristics of sound fields and propagation parameters
43.20.Bi Mathematical theory of wave propagation
43.20.Fn Scattering of acoustic waves
43.20.Hq Velocity and attenuation of acoustic waves
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Broadband source localization using horizontal-beam acoustic intensity striations

Altan Turgut, Marshall Orr, and Daniel Rouseff

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 73-83 (2010); (11 pages) | Cited 7 times

Online Publication Date: 05 Jan 2010

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Waveguide invariant theory is applied to horizontal line array (HLA) beamformer output to localize moving broadband noise sources from measured acoustic intensity striation patterns. Acoustic signals emitted by ships of opportunity (merchant ships) were simultaneously recorded on a HLA and three hydrophones separated by 10 km during the RAGS03 (relationship between array gain and shelf-break fluid processes) experiment. Hough transforms are used to estimate both the waveguide invariant parameter “beta” and the ratio of source range at the closest point of approach to source speed from the observed striation patterns. Broadband (50–150-Hz) acoustic data-sets are used to demonstrate source localization capability as well as inversion capability of waveguide invariant parameter beta. Special attention is paid to bathymetric variability since the acoustic intensity striation patterns seem to be influenced by range-dependent bathymetry of the experimental area. The Hough transform method is also applied to the HLA beam-time record data and to the acoustic intensity data from three distant receivers to validate the estimation results from HLA beamformer output. Good agreement of the results from all three approaches suggests the feasibility of locating broadband noise sources and estimating waveguide invariant parameter beta in shallow waters.
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43.30.Bp Normal mode propagation of sound in water
43.30.Wi Passive sonar systems and algorithms, matched field processing in underwater acoustics
43.30.Zk Experimental modeling
43.60.Lq Acoustic imaging, displays, pattern recognition, feature extraction

Geoacoustic inversions and localizations with adaptively beamformed data from a surface ship of opportunity source

Steven A. Stotts and Robert A. Koch

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 84-95 (2010); (12 pages) | Cited 2 times

Online Publication Date: 05 Jan 2010

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A technique has been developed for incorporating adaptively beamformed (ABF) data into geoacoustic inversions and source localizations based on matched-field processing. Rather than adaptively adjusting matched-field weights, for this paper ABF processing is applied to construct subaperture beam data from which the inversions and localizations are derived. This application of ABF processing to inversion and localization is successfully demonstrated with data collected on a horizontal line array from a surface ship of opportunity source (SSOS). When measured data representing noise from one or more interfering sources at various levels are injected into the data collected from the SSOS, the inversion processing with ABF subaperture data is successful at interferer noise levels exceeding the SSOS levels by 10–13 dB and for which the inversion processing with conventionally beamformed data fails.
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43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.60.Kx Matched field processing
43.60.Mn Adaptive processing
43.30.Bp Normal mode propagation of sound in water

Observations and modeling of angular compression and vertical spatial coherence in sea surface forward scattering

Peter H. Dahl

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 96-103 (2010); (8 pages) | Cited 1 time

Online Publication Date: 05 Jan 2010

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Measurements and modeling of spatial coherence and related angular spreading associated with forward scattering from the sea surface are presented. The measurements were taken in waters 80 m deep off the New Jersey coast in August 2006. Acoustic signals from a source at depth 40 m were recorded on a vertical line array of length 1.4 m, centered at depth 25 m, and at range 200 m. Measurements in the 14–20-kHz frequency range are reported; the rms waveheight H was 0.16 m, setting kH as ∼ 10 where k is acoustic wavenumber. A systematic study of measurements taken over four source–receiver bearing angles separated by 90° suggests a null influence of changing bearing angle or equivalently directional wave effects. Sound speed was characterized by a downward-refracting profile. Refraction modifies the vertical angular spread due to rough sea surface scattering, which can be understood from Snell’s law. The Snell mapping is smooth, so an approximation based on the mean grazing angle provides a functional relation between the angular variance near the surface and that at the receiver. The latter is measurably reduced owing to refraction, the effect called angular compression, and a parameter that quantifies this effect is defined.
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43.30.Re Signal coherence or fluctuation due to sound propagation/scattering in the ocean
43.30.Zk Experimental modeling
43.30.Hw Rough interface scattering

Low-frequency target strength and abundance of shoaling Atlantic herring (Clupea harengus) in the Gulf of Maine during the Ocean Acoustic Waveguide Remote Sensing 2006 Experiment

Zheng Gong, Mark Andrews, Srinivasan Jagannathan, Ruben Patel, J. Michael Jech, Nicholas C. Makris, and Purnima Ratilal

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 104-123 (2010); (20 pages) | Cited 5 times

Online Publication Date: 05 Jan 2010

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The low-frequency target strength of shoaling Atlantic herring (Clupea harengus) in the Gulf of Maine during Autumn 2006 spawning season is estimated from experimental data acquired simultaneously at multiple frequencies in the 300–1200 Hz range using (1) a low-frequency ocean acoustic waveguide remote sensing (OAWRS) system, (2) areal population density calibration with several conventional fish finding sonar (CFFS) systems, and (3) low-frequency transmission loss measurements. The OAWRS system’s instantaneous imaging diameter of 100 km and regular updating enabled unaliased monitoring of fish populations over ecosystem scales including shoals of Atlantic herring containing hundreds of millions of individuals, as confirmed by concurrent trawl and CFFS sampling. High spatial-temporal coregistration was found between herring shoals imaged by OAWRS and concurrent CFFS line-transects, which also provided fish depth distributions. The mean scattering cross-section of an individual shoaling herring is found to consistently exhibit a strong, roughly 20 dB/octave roll-off with decreasing frequency in the range of the OAWRS survey over all days of the roughly 2-week experiment, consistent with the steep roll-offs expected for sub-resonance scattering from fish with air-filled swimbladders.
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43.30.Sf Acoustical detection of marine life; passive and active
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.30.Vh Active sonar systems

Spatial and temporal patterns of Risso’s dolphin echolocation in the Southern California Bight

Melissa S. Soldevilla, Sean M. Wiggins, and John A. Hildebrand

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 124-132 (2010); (9 pages) | Cited 12 times

Online Publication Date: 05 Jan 2010

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Geographical and temporal trends in echolocation clicking activity can lead to insights into the foraging and migratory behaviors of pelagic dolphins. Using autonomous acoustic recording packages, the geographical, diel, and seasonal patterns of Risso’s dolphin (Grampus griseus) echolocation click activity are described for six locations in the Southern California Bight between 2005 and 2007. Risso’s dolphin echolocation click bouts are identified based on their unique spectral characteristics. Click bouts were identified on 739 of 1959 recording days at all 6 sites, with the majority occurring at nearshore sites. A significant diel pattern is evident in which both hourly occurrences of click bouts and click rates are higher at night than during the day. At all nearshore sites, Risso’s dolphin clicks were identified year-round, with the highest daily occurrence at the southern end of Santa Catalina Island. Seasonal and interannual variabilities in occurrence were high across sites with peak occurrence in autumn of most years at most sites. These results suggest that Risso’s dolphins forage at night and that the southern end of Santa Catalina Island represents an important habitat for Risso’s dolphins throughout the year.
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43.30.Sf Acoustical detection of marine life; passive and active
43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar

Localization of sperm whales in a group using clicks received at two separated short baseline arrays

Ryo Hirotsu, Masao Yanagisawa, Tamaki Ura, Masao Sakata, Harumi Sugimatsu, Junichi Kojima, and Rajendar Bahl

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 133-147 (2010); (15 pages) | Cited 3 times

Online Publication Date: 05 Jan 2010

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In this paper, a sperm whale click analysis scheme is proposed in order to calculate the position of individual sperm whales in a group using data received at two arrays deployed near the surface. The proposed method mainly consists of two parts: short baseline (SBL) with classification and long baseline (LBL) with class matching. In SBL with classification, a click is automatically detected, and its direction of arrival is calculated. The clicks are then classified based on their direction vectors. The class data are then sent together with direction data and matched to the other array’s class data. LBL with class matching is used for localization. The classification algorithm can be used to estimate the number of whales clicking and to list potential candidates for LBL matching. As a result, the proposed method is able to localize the positions of the whales in a group. The performance of the proposed method is evaluated using data recorded off Ogasawara islands with two arrays near the surface. The three-dimensional underwater trajectories of six sperm whales are extracted to demonstrate the capability of the proposed method.
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43.30.Wi Passive sonar systems and algorithms, matched field processing in underwater acoustics
43.80.Ev Acoustical measurement methods in biological systems and media
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Experimental validation of a time domain simulation of high frequency ultrasonic propagation in a suspension of rigid particles

Belfor Galaz, Guillaume Haïat, Romain Berti, Nicolas Taulier, Jean-Jacques Amman, and Wladimir Urbach

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 148-154 (2010); (7 pages) | Cited 3 times

Online Publication Date: 05 Jan 2010

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Ultrasonic propagation in suspensions of particles is a difficult problem due to the random spatial distribution of the particles. Two-dimensional finite-difference time domain simulations of ultrasonic propagation in suspensions of polystyrene 5.3 μm diameter microdisks are performed at about 50 MHz. The numerical results are compared with the Faran model, considering an isolated microdisk, leading to a maximum difference of 15% between the scattering cross-section values obtained analytically and numerically. Experiments are performed with suspensions in through transmission and backscattering modes. The attenuation coefficient at 50 MHz (α), the ultrasonic velocity (V), and the relative backscattered intensity (IB) are measured for concentrations from 2 to 25 mg/ml, obtained by modifying the number of particles. Each experimental ultrasonic parameter is compared to numerical results obtained by averaging the results derived from 15 spatial distributions of microdisks. α increases with the concentration from 1 to 17 dB/cm. IB increases with concentration from 2 to 16 dB. The variation of V versus concentration is compared with the numerical results, as well as with an effective medium model. A good agreement is found between experimental and numerical results (the larger discrepancy is found for α with a difference lower than 2.1 dB/cm).
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43.35.Bf Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in liquids, liquid crystals, suspensions, and emulsions
43.20.Hq Velocity and attenuation of acoustic waves
43.20.Px Transient radiation and scattering
43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants

Efficient frequency-domain finite element modeling of two-dimensional elastodynamic scattering

Paul D. Wilcox and Alexander Velichko

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 155-165 (2010); (11 pages) | Cited 9 times

Online Publication Date: 05 Jan 2010

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A frequency-domain finite element technique is presented that enables the complete characterization of a finite-sized scatterer using a minimum number of separate model executions and a relatively small spatial modeling domain. The technique is implemented using a commercial finite element package. A certain forcing profile is applied at a set of points surrounding the scatterer to cause a uni-modal plane wave to be incident on the scatterer from a specified direction. The scattered field is recorded and decomposed first into modes and then into far-field scattering coefficients in different directions. The data obtained from the model are represented in a scattering matrix that describes the far-field scattering response for all combinations of incident and scattering angles. The information in the scattering matrix can be efficiently represented in the Fourier domain by another matrix containing a finite number of Fourier coefficients. It is shown how the complete scattering behavior in both the near- and far-field can be extracted from the matrix of Fourier coefficients. Modeling accuracy is examined in various ways, including a comparison with the analytical solution for a circular cavity, and guidelines for the selection of modeling parameters are given.
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43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
43.20.Gp Reflection, refraction, diffraction, interference, and scattering of elastic and poroelastic waves

Simplified expressions of the subtracted Kramers–Kronig relations using the expanded forms applied to ultrasonic power-law systems

Joel Mobley

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 166-173 (2010); (8 pages) | Cited 1 time

Online Publication Date: 05 Jan 2010

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The Kramers–Kronig (KK) relations are a large class of integral transformations that exploit the broad principle of simple causality in order to link the physical properties of matter and materials. In applications to the complex-valued wavenumber for acoustic propagation, the method of subtractions is used to form convergent integral relations between the phase velocity and the attenuation coefficient. When the method of subtractions is applied in the usual manner, the integrands in the relations become unnecessarily complicated. In this work, an expanded form of the subtracted relations is presented, which is essentially a truncated Taylor series expansion of the Hilbert transforms. The implementation of the relations only requires the explicit evaluation of two simply expressed integrals involving the Hilbert transform kernel. These two integrals determine the values of the other terms in the subtracted relations, demonstrating the computational efficiency of the technique. The method is illustrated analytically through its application to power-law attenuation coefficients and its associated dispersion, which are observed in a wide variety of materials. This approach explicitly shows the central role of the Hilbert transform kernel in the KK relations, which can become obscured in other formulations.
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43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
43.20.Hq Velocity and attenuation of acoustic waves
43.35.Bf Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in liquids, liquid crystals, suspensions, and emulsions

Sound velocities and thermodynamic properties of water to 700 MPa and −10 to 100 °C

Steve Vance and J. Michael Brown

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 174-180 (2010); (7 pages) | Cited 5 times

Online Publication Date: 05 Jan 2010

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Sound velocities in liquid water were measured by the method of impulsive stimulated scattering in a sapphire-windowed high-pressure cell from −10 to 100 °C and pressures as high as 700 MPa. Velocity measurements are compared with previous experimental efforts relative to the International Association for the Properties of Water and Steam (IAPWS-95) formulation for the equations of state. At 0 and −10 °C, sound velocities are in agreement with the one previously published study at sub-zero temperatures to 350 MPa. At ambient and elevated temperatures, differences between the present measurements and IAPWS-95 velocities approach 0.5% near 700 MPa. Inversion of velocity data for density yields results within IAPWS-95 uncertainties, except at the highest temperatures, where elevated sound velocity at high pressure corresponds to as much as −0.2% disagreement with IAPWS-95.
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43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
43.30.Bp Normal mode propagation of sound in water
43.20.Hq Velocity and attenuation of acoustic waves
43.20.Ye Measurement methods and instrumentation

Experimental and theoretical study of acoustic waves generated by a laser line pulse in an optically absorptive isotropic cylinder

D. Ségur, A. L. Shuvalov, B. Audoin, and Y. D. Pan

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 181-185 (2010); (5 pages) | Cited 3 times

Online Publication Date: 05 Jan 2010

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The generation of acoustic waves by a line-focused laser pulse in an optically absorptive cylinder is studied experimentally and theoretically. Experiments are performed on a 5 mm diameter NG5 colored glass rod using Nd:yttrium aluminum garnet laser, which delivers 5 ns pulses. The numerical simulation is based on the semi-analytical model of a radially distributed thermoelastic source, which takes into account penetration of laser energy into the bulk of the sample. Good agreement between the experimental and calculated wave forms is observed. Comparison of these wave forms with an auxiliary simulation, which assumes the model of a dipole source located at the cylinder surface, reveals the effect of optical penetration on the shape of the wave form and also on the relative amplitude of bulk and surface waves.
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43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect

Analytical study of the acoustic field in a spherical resonator for single bubble sonoluminescence

Damián Dellavale, Raúl Urteaga, and Fabián J. Bonetto

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 186-197 (2010); (12 pages) | Cited 2 times

Online Publication Date: 05 Jan 2010

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The acoustic field in the liquid within a spherical solid shell is calculated. The proposed model takes into account Stoke’s wave equation in the viscous fluid, the membrane theory to describe the solid shell motion and the energy loss through the external couplings of the system. A point source at the resonator center is included to reproduce the acoustic emission of a sonoluminescence bubble. Particular calculations of the resulting acoustic field are performed for viscous liquids of interest in single bubble sonoluminescence. The model reveals that in case of radially symmetric modes of low frequency, the quality factor is mainly determined by the acoustic energy flowing through the mechanical coupling of the resonator. Alternatively, for high frequency modes the quality factor is mainly determined by the viscous dissipation in the liquid. Furthermore, the interaction between the bubble acoustic emission and the resonator modes is analyzed. It was found that the bubble acoustic emission produces local maxima in the resonator response. The calculated amplitudes and relative phases of the harmonics constituting the bubble acoustic environment can be used to improve multi-frequency driving in sonoluminescence.
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43.35.Hl Sonoluminescence

Excitation and focusing of Lamb waves in a multilayered anisotropic plate

Bastien Chapuis, Nicolas Terrien, and Daniel Royer

J. Acoust. Soc. Am. Volume 127, Issue 1, pp. 198-203 (2010); (6 pages) | Cited 6 times

Online Publication Date: 05 Jan 2010

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The radiation of Lamb waves by an axisymmetric source on the surface of an anisotropic plate is investigated. An analytical expression of the Green’s function, valid in the far field domain, is derived. This approximation shows that the anisotropy of the propagation medium induces a focusing of Lamb modes in some directions, which correspond to minima of the slowness. Numerical simulations and experiments demonstrate that for the fundamental A0 and S0 modes, this phenomenon, analog to the phonon focusing effect, can be very strong in materials such as composite fiber-reinforced polymers. This effect due to the plate anisotropy must be correctly taken into account, for example, in order to develop systems for in situ structural health monitoring. The choice of the most appropriate Lamb mode, the excitation frequency, and the design of the array of piezoelectric disks used as transmitters and receivers depends on such considerations.
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43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
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