• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Nov 2009

Volume 126, Issue 5, pp. EL107-2839

Page 1 of 6 Pages Next Page | Jump to Page
back to top
RSS Feeds
FREE

Ultra-wide sensor arcs for low frequency sonar detection with a baffled cylindrical array

Derek C. Bertilone, Chaoying Bao, Ben C. Travaglione, and Damien S. Killeen

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL107-EL111 (2009); (5 pages)

Online Publication Date: 22 Sep 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Passive detection with a baffled cylindrical array can potentially be improved at low frequencies by exploiting signal diffraction around the baffle. A model based on infinite rigid cylinder scattering suggests that large gains in signal-to-noise ratio are potentially available to adaptive beamformers if the sensor arc is widened to include sensors in the acoustic shadow. However, elastic scatter effects become increasingly important as frequency decreases, so the gains obtained in practice are unknown. The gains in detection performance are examined in this letter by analyzing data recorded at sea from a platform-mounted sonar array.
Show PACS
43.60.Fg Acoustic array systems and processing, beam-forming
FREE

Explosion localization via infrasound

Curt A. L. Szuberla, John V. Olson, and Kenneth M. Arnoult

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL112-EL116 (2009); (5 pages)

Online Publication Date: 24 Sep 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Two acoustic source localization techniques were applied to infrasonic data and their relative performance was assessed. The standard approach for low-frequency localization uses an ensemble of small arrays to separately estimate far-field source bearings, resulting in a solution from the various back azimuths. This method was compared to one developed by the authors that treats the smaller subarrays as a single, meta-array. In numerical simulation and a field experiment, the latter technique was found to provide improved localization precision everywhere in the vicinity of a 3-km-aperture meta-array, often by an order of magnitude.
Show PACS
43.60.Jn Source localization and parameter estimation
43.28.Dm Infrasound and acoustic-gravity waves
FREE

The use of non-collinear mixing for nonlinear ultrasonic detection of plasticity and fatigue

Anthony J. Croxford, Paul D. Wilcox, Bruce W. Drinkwater, and Peter B. Nagy

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL117-EL122 (2009); (6 pages) | Cited 3 times

Online Publication Date: 24 Sep 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter reports on the application of the non-collinear mixing technique to the ultrasonic measurement of material nonlinearity to assess plasticity and fatigue damage. Non-collinear mixing is potentially more attractive for assessing material state than other nonlinear ultrasonic techniques because system nonlinearities can be both independently measured and largely eliminated. Here, measurements made on a sample after plastic deformation and on a sample subjected to low-cycle fatigue show that the non-collinear technique is indeed capable of measuring changes in both, and is therefore a viable inspection technique for these types of material degradation.
Show PACS
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products
43.35.Yb Ultrasonic instrumentation and measurement techniques
43.25.Zx Measurement methods and instrumentation for nonlinear acoustics
FREE

Attention modulates auditory adaptation produced by amplitude modulation

Takayuki Kawashima

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL123-EL127 (2009); (5 pages) | Cited 2 times

Online Publication Date: 24 Sep 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of attention on adaptation produced by amplitude modulation (AM) was examined. In different experimental conditions, listeners’ AM detection thresholds for a 2 kHz test tone were measured after exposing them to an adapting sound that was presented simultaneously with speech distractors. Magnitude of an aftereffect, calculated as the elevation of the thresholds caused by adaptation, was smaller when the listeners shift attention away from the adaptor to the distractor voice than when they attended to the adaptor. The results suggest that the AM of unattended sounds may not be fully analyzed compared to that of attended sounds.
Show PACS
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Rq Dichotic listening
FREE

Perceptual fusion of polyphonic pitch in cochlear implant users

Patrick J. Donnelly, Benjamin Z. Guo, and Charles J. Limb

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL128-EL133 (2009); (6 pages) | Cited 3 times

Online Publication Date: 29 Sep 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In music, multiple pitches often occur simultaneously, an essential feature of harmony. In the present study, the authors assessed the ability of cochlear implant (CI) users to perceive polyphonic pitch. Acoustically presented stimuli consisted of one, two, or three superposed tones with different fundamental frequencies (f0). The normal hearing control group obtained significantly higher mean scores than the CI group. CI users performed near chance levels in recognizing two- and three-pitch stimuli, and demonstrated perceptual fusion of multiple pitches as single-pitch units. These results suggest that limitations in polyphonic pitch perception may significantly impair music perception in CI users.
Show PACS
43.66.Ts Auditory prostheses, hearing aids
43.66.Hg Pitch
43.75.Cd Music perception and cognition
FREE

Development of perceptual sensitivity to extrinsic vowel duration in infants learning American English

Eon-Suk Ko, Melanie Soderstrom, and James Morgan

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL134-EL139 (2009); (6 pages) | Cited 2 times

Online Publication Date: 29 Sep 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
8- and 14-month-old infants’ perceptual sensitivity to vowel duration conditioned by post-vocalic consonantal voicing was examined. Half the infants heard CVC stimuli with short vowels, and half heard stimuli with long vowels. In both groups, stimuli with voiced and voiceless final consonants were compared. Older infants showed significant sensitivity to mismatching vowel duration and consonant voicing in the short condition but not the long condition; younger infants were not sensitive to such mismatching in either condition. The results suggest that infants’ sensitivity to extrinsic vowel duration begins to develop between 8 and 14 months.
Show PACS
43.71.Ft Development of speech perception
43.70.Mn Relations between speech production and perception
43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
FREE

Straightforward estimation of the elastic constants of an isotropic cube excited by a single percussion

F. J. Nieves, F. Gascón, A. Bayón, and F. Salazar

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL140-EL146 (2009); (7 pages)

Online Publication Date: 08 Oct 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ritz’s method is applied to calculate accurate values of the lowest non-dimensional natural frequencies of a freely vibrating isotropic cube. The dependence of such frequencies and their quotients on Poisson’s ratio is established. Vibration of a cube caused by percussion is detected at a point by a laser interferometer. With the help of the tables and graphs provided and with the values of the first lowest frequencies obtained experimentally in a single test, Poisson’s ratio and the shear modulus are calculated by means of elementary arithmetical operations.
Show PACS
43.40.At Experimental and theoretical studies of vibrating systems
43.40.Dx Vibrations of membranes and plates
43.20.Ks Standing waves, resonance, normal modes
FREE

A Bayesian approach to modal decomposition in ocean acoustics

Zoi-Heleni Michalopoulou

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL147-EL152 (2009); (6 pages) | Cited 1 time

Online Publication Date: 09 Oct 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A Bayesian approach is developed for modal decomposition from time-frequency representations of broadband acoustic signals propagating in underwater media. The goal is to obtain accurate estimates and posterior probability distributions of modal frequencies arriving at a specific time and their corresponding amplitudes, which can be employed for geoacoustic inversion. The proposed approach, optimized via Gibbs sampling, provides uncertainty information on modal characteristics via the posterior distributions, typically unavailable from traditional methods.
Show PACS
43.60.Hj Time-frequency signal processing, wavelets
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.60.Jn Source localization and parameter estimation
FREE

Relation of sound absorption and shallow water modal attenuation to plane wave attenuation

Allan D. Pierce

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL153-EL159 (2009); (7 pages)

Online Publication Date: 14 Oct 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Prediction of attenuation of acoustic fields in weakly absorbing media often uses the substitution of (ω/c)→(ω/c)+iαpw into the idealized equations for constant frequency, with αpw representing the local plane wave attenuation coefficient. This assumption is flawed whenever the local absorption of sound is proportional to the square of the gradient of the acoustic pressure, as is the case when the absorption is caused by fluid velocity relaxation. A realistic analysis yields an improved weighting function over depth for determination of guided mode attenuation coefficients.
Show PACS
43.30.Es Velocity, attenuation, refraction, and diffraction in water, Doppler effect
43.30.Ma Acoustics of sediments; ice covers, viscoelastic media; seismic underwater acoustics
43.20.Hq Velocity and attenuation of acoustic waves
43.20.Bi Mathematical theory of wave propagation
FREE

Analysis of pausing behavior in spontaneous speech using real-time magnetic resonance imaging of articulation

Vikram Ramanarayanan, Erik Bresch, Dani Byrd, Louis Goldstein, and Shrikanth S. Narayanan

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL160-EL165 (2009); (6 pages) | Cited 2 times

Online Publication Date: 19 Oct 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is hypothesized that pauses at major syntactic boundaries (i.e., grammatical pauses), but not ungrammatical (e.g., word search) pauses, are planned by a high-level cognitive mechanism that also controls the rate of articulation around these junctures. Real-time magnetic resonance imaging is used to analyze articulation at and around grammatical and ungrammatical pauses in spontaneous speech. Measures quantifying the speed of articulators were developed and applied during these pauses as well as during their immediate neighborhoods. Grammatical pauses were found to have an appreciable drop in speed at the pause itself as compared to ungrammatical pauses, which is consistent with our hypothesis that grammatical pauses are indeed choreographed by a central cognitive planner.
Show PACS
43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation
43.72.Ar Speech analysis and analysis techniques; parametric representation of speech
FREE

Acoustic coupling between pistons in a rigid baffle

Kassiani Kotsidou and Charles Thompson

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. EL166-EL169 (2009); (4 pages)

Online Publication Date: 19 Oct 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper demonstrates the merit of “matched asymptotic expansions” by applying the method to the analysis of the acoustical coupling between vibrating pistons. The accuracy of the method is verified by comparing the results of this study with existing solutions. The method uses the disparity between the characteristic length scale of the nearly incompressible fluid motion near the piston and that of the far field acoustic pressure. The velocity potential in each region is developed in terms of a singular perturbation expansion. Finally, the combination of the locally valid solutions leads to a global solution.
Show PACS
43.38.Hz Transducer arrays, acoustic interaction effects in arrays
back to top
RSS Feeds

High-rate envelope information in many channels provides resistance to reduction of speech intelligibility produced by multi-channel fast-acting compression

Michael A. Stone, Christian Füllgrabe, and Brian C. J. Moore

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2155-2158 (2009); (4 pages) | Cited 6 times

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The intelligibility of speech in a competing-speech background was measured for signals that were subjected to multi-channel compression and then tone vocoded. The lowpass filter used to extract the envelopes in the vocoder preserved only low-rate envelope cues (E filter) or also preserved pitch-related cues (P filter). Intelligibility worsened with increasing number of compression channels and compression speed, but this effect was markedly reduced when the P filter was used and the number of vocoder channels was 16 as compared to 8. Thus, providing high-rate envelope cues in many channels provides resistance to the deleterious effects of fast compression.
Show PACS
43.66.Ts Auditory prostheses, hearing aids
43.71.Gv Measures of speech perception (intelligibility and quality)
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music

Analysis of categorical response data: Use logistic regression rather than endpoint-difference scores or discriminant analysis

Geoffrey Stewart Morrison and Maria V. Kondaurova

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2159-2162 (2009); (4 pages) | Cited 4 times

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Example of a typical second-language (L2) speech perception experiment: Synthetic vowel stimuli from a two-dimensional grid of points in which acoustic properties vary systematically in duration and spectral properties are classified as English /i/ or /I/ by L2-English listeners. In a number of studies, the data from such experiments have been analyzed using endpoint-difference scores or discriminant analysis. The current letter describes theoretical problems inherent in the first procedure in general, and in the application of the second procedure to data of this type in particular. Logistic regression is proposed as an alternative, which does not suffer from these problems.
Show PACS
43.71.An Models and theories of speech perception
43.71.Hw Cross-language perception of speech
43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
back to top
RSS Feeds

Near resonant bubble acoustic cross-section corrections, including examples from oceanography, volcanology, and biomedical ultrasound

Michael A. Ainslie and Timothy G. Leighton

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2163-2175 (2009); (13 pages) | Cited 11 times

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The scattering cross-section σs of a gas bubble of equilibrium radius R0 in liquid can be written in the form σs = 4πR02/[(ω12/ω2−1)2+δ2], where ω is the excitation frequency, ω1 is the resonance frequency, and δ is a frequency-dependent dimensionless damping coefficient. A persistent discrepancy in the frequency dependence of the contribution to δ from radiation damping, denoted δrad, is identified and resolved, as follows. Wildt’s [Physics of Sound in the Sea (Washington, DC, 1946), Chap. 28] pioneering derivation predicts a linear dependence of δrad on frequency, a result which Medwin [Ultrasonics 15, 7–13 (1977)] reproduces using a different method. Weston [Underwater Acoustics, NATO Advanced Study Institute Series Vol. II, 55–88 (1967)] , using ostensibly the same method as Wildt, predicts the opposite relationship, i.e., that δrad is inversely proportional to frequency. Weston’s version of the derivation of the scattering cross-section is shown here to be the correct one, thus resolving the discrepancy. Further, a correction to Weston’s model is derived that amounts to a shift in the resonance frequency. A new, corrected, expression for the extinction cross-section is also derived. The magnitudes of the corrections are illustrated using examples from oceanography, volcanology, planetary acoustics, neutron spallation, and biomedical ultrasound. The corrections become significant when the bulk modulus of the gas is not negligible relative to that of the surrounding liquid.
Show PACS
43.20.Ks Standing waves, resonance, normal modes
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.35.Bf Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in liquids, liquid crystals, suspensions, and emulsions
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products
back to top
RSS Feeds

Measurement of acoustic streaming in a closed-loop traveling wave resonator using laser Doppler velocimetry

Cyril Desjouy, Guillaume Penelet, Pierrick Lotton, and James Blondeau

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2176-2183 (2009); (8 pages)

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper deals with the measurement of acoustic particle velocity and acoustic streaming velocity in a closed-loop waveguide in which a resonant traveling acoustic wave is sustained by two loudspeakers appropriately controlled in phase and amplitude. An analytical model of the acoustic field and a theoretical estimate of the acoustic streaming are presented. The measurement of acoustic and acoustic streaming velocities is performed using laser Doppler velocimetry. The experimental results obtained show that the curvature of the resonator impacts the acoustic velocity and the profile of acoustic streaming. The quadratic dependence of the acoustic streaming velocity on the acoustic pressure amplitude is verified and the measured cross-sectional average streaming velocity is in good agreement with the value predicted by the theoretical estimate.
Show PACS
43.25.Nm Acoustic streaming

Acoustic measurement of bubble size in an inkjet printhead

Roger Jeurissen, Arjan van der Bos, Hans Reinten, Marc van den Berg, Herman Wijshoff, Jos de Jong, Michel Versluis, and Detlef Lohse

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2184-2190 (2009); (7 pages) | Cited 3 times

Online Publication Date: 05 Nov 2009

Full Text: | Download PDF

Show Abstract
The volume of a bubble in a piezoinkjet printhead is measured acoustically. The method is based on a numerical model of the investigated system. The piezo not only drives the system but it is also used as a sensor by measuring the current it generates. The numerical model is used to predict this current for a given bubble volume. The inverse problem is to infer the bubble volume from an experimentally obtained piezocurrent. By solving this inverse problem, the size and position of the bubble can thus be measured acoustically. The method is experimentally validated with an inkjet printhead that is augmented with a glass connection channel, through which the bubble was observed optically, while at the same time the piezocurrent was measured. The results from the acoustical measurement method correspond closely to the results from the optical measurement.
Show PACS
43.25.Yw Nonlinear acoustics of bubbly liquids
43.38.Fx Piezoelectric and ferroelectric transducers
43.35.Yb Ultrasonic instrumentation and measurement techniques
43.30.Zk Experimental modeling
back to top
RSS Feeds

Long range sound propagation over a sea surface

Karl Bolin, Mathieu Boué, and Ilkka Karasalo

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2191-2197 (2009); (7 pages) | Cited 1 time

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper describes methodology and results from a model-based analysis of data on sound transmission from controlled sound sources at sea to a 10-km distant shore. The data consist of registrations of sound transmission loss together with concurrently collected atmospheric data at the source and receiver locations. The purpose of the analysis is to assess the accuracy of methods for transmission loss prediction in which detailed data on the local geography and atmospheric conditions are used for computation of the sound field. The results indicate that such sound propagation predictions are accurate and reproduce observed variations in the sound level as function of time in a realistic way. The results further illustrate that the atmospheric model must include a description of turbulence effects to ensure predicted noise levels to remain realistically high during periods of sound shadow.
Show PACS
43.28.Fp Outdoor sound propagation through a stationary atmosphere, meteorological factors
43.50.Vt Topographical and meteorological factors in noise propagation

Acoustic intensity-based method for sound radiations in a uniform flow

Chao Yu, Zhengfang Zhou, and Mei Zhuang

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2198-2205 (2009); (8 pages) | Cited 1 time

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An acoustic intensity-based method (AIBM) is extended and verified for predicting sound radiation in a subsonic uniform flow. The method assumes that the acoustic propagation is governed by the modified Helmholtz equation on and outside of a control surface, which encloses all the noise sources and nonlinear effects. With acoustic pressure derivative and its co-located acoustic pressure as input from an open control surface, the unique solution of the modified Helmholtz equation is obtained by solving the least squares problem. The AIBM is coupled with near-field Computational Fluid Dynamics (CFD)/Computational Aeroacoustics (CAA) methods to predict sound radiation of model aeroacoustic problems. The effectiveness of this hybrid approach has been demonstrated by examples of both tonal and broadband noise. Since the AIBM method is stable and accurate based on the input acoustic data from an open surface in a radiated field, it is therefore advantageous for the far-field prediction of aerodynamics noise propagation when an acoustic input from a closed control surface, like the Ffowcs Williams–Hawkings surface, is not available [ Philos. Trans. R. Soc. London, Ser. A 264, 321–342 (1969) ].
Show PACS
43.28.Ra Generation of sound by fluid flow, aerodynamic sound and turbulence
43.20.Bi Mathematical theory of wave propagation
43.20.Fn Scattering of acoustic waves
43.20.El Reflection, refraction, diffraction of acoustic waves
back to top
RSS Feeds

Modeling of acoustic penetration into sandy sediments: Physical and geometrical aspects

V. Aleshin and L. Guillon

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2206-2214 (2009); (9 pages)

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Two different approaches to the problem of acoustic penetration into sandy marine sediments are considered: application of the Buckingham constitutive model for sediment with a plane surface and boundary element analysis of a rough surface of sediment represented as a homogeneous fluid. By a careful modeling of the constitutive behavior for plane seafloors, it is possible to partly reproduce some features of known experimental dependencies for acoustical pressure. However, accounting for roughness appears to be more important. Accordingly, the authors present a detailed numerical analysis of penetration into rough sediments using the boundary element method. The simulation results support conclusions reached by other investigators and demonstrate how local surface irregularities violate the evanescence condition that holds for a plane interface at subcritical incidence, thus considerably increasing penetration. The results apply to the frequency range 0.5–50 kHz and grazing angles larger than approximately 6°–8° at 10–50 kHz. For lower frequencies, when diffraction becomes important, the lowest possible grazing angle strongly depends on the range covered by the incident beam and is, in general, considerably larger. The authors provide several characteristic examples with frequencies 5 and 15 kHz and grazing angles 15°–30° illustrating the impact of roughness on penetration.
Show PACS
43.30.Hw Rough interface scattering
43.30.Ma Acoustics of sediments; ice covers, viscoelastic media; seismic underwater acoustics

Under-ice noise generated from diamond exploration in a Canadian sub-arctic lake and potential impacts on fishes

D. Mann, P. Cott, and B. Horne

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2215-2222 (2009); (8 pages)

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Mineral exploration is increasing in Canada, particularly in the north where extensive diamond mining and exploration are occurring. This study measured the under-ice noise produced by a variety of anthropogenic sources (drilling rigs, helicopters, aircraft landing and takeoff, ice-road traffic, augers, snowmobiles, and chisels) at a winter-based diamond exploration project on Kennady Lake in the Northwest Territories, Canada to infer the potential impact of noise on fishes in the lake. The root-mean-square noise level measured 5 m from a small diameter drill was approximately 46 dB greater (22 kHz bandwidth) than ambient noise, while the acoustic particle velocity was approximately 40 dB higher than ambient levels. The loudest sounds at the exploration site were produced by ice cracking, both natural and during landing and takeoff of a C130 Hercules aircraft. However, even walking on the snow above the ice raised ambient sound levels by approximately 30 dB. Most of the anthropogenic sounds are likely detectable by fishes with hearing specializations, such as chubs and suckers. Other species without specialized hearing adaptations will detect these sounds only close to the source. The greatest potential impact of noise from diamond exploration is likely to be the masking of sounds for fishes with sensitive hearing.
Show PACS
43.30.Nb Noise in water; generation mechanisms and characteristics of the field
43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms
43.50.Rq Environmental noise, measurement, analysis, statistical characteristics
43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing

Travel-time sensitivity kernels in long-range propagation

E. K. Skarsoulis, B. D. Cornuelle, and M. A. Dzieciuch

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2223-2233 (2009); (11 pages)

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Wave-theoretic travel-time sensitivity kernels (TSKs) are calculated in two-dimensional (2D) and three-dimensional (3D) environments and their behavior with increasing propagation range is studied and compared to that of ray-theoretic TSKs and corresponding Fresnel-volumes. The differences between the 2D and 3D TSKs average out when horizontal or cross-range marginals are considered, which indicates that they are not important in the case of range-independent sound-speed perturbations or perturbations of large scale compared to the lateral TSK extent. With increasing range, the wave-theoretic TSKs expand in the horizontal cross-range direction, their cross-range extent being comparable to that of the corresponding free-space Fresnel zone, whereas they remain bounded in the vertical. Vertical travel-time sensitivity kernels (VTSKs)—one-dimensional kernels describing the effect of horizontally uniform sound-speed changes on travel-times—are calculated analytically using a perturbation approach, and also numerically, as horizontal marginals of the corresponding TSKs. Good agreement between analytical and numerical VTSKs, as well as between 2D and 3D VTSKs, is found. As an alternative method to obtain wave-theoretic sensitivity kernels, the parabolic approximation is used; the resulting TSKs and VTSKs are in good agreement with normal-mode results. With increasing range, the wave-theoretic VTSKs approach the corresponding ray-theoretic sensitivity kernels.
Show PACS
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.30.Bp Normal mode propagation of sound in water

Effects of sea-surface conditions on passive fathometry and bottom characterization

Steven L. Means and Martin Siderius

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2234-2241 (2009); (8 pages) | Cited 1 time

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Recently, a method has been developed that exploits the correlation properties of the ocean’s ambient noise to measure water depth (a passive fathometer) and seabed layering [ M. Siderius et al., J. Acoust. Soc. Am. 120, 1315–1323 (2006) ]. This processing is based on the cross-correlation between the surface noise and the echo return from the seabed. To quantitatively study the dependency between processing and environmental factors such as wind speed, measurements were made using a fixed hydrophone array while simultaneously characterizing the environment. The measurements were made in 2006 in the shallow waters (25 m) approximately 75 km off the coast of Savannah, GA. A Navy tower about 100 m from the array was used to measure wind speed and to observe the sea-surface using a video camera. Data were collected in various environmental conditions with wind speeds ranging from 5 to 21 m/s and wave heights of 1–3.4 m. The data are analyzed to quantify the dependency of passive fathometer results on wind speeds, wave conditions, and averaging times. One result shows that the seabed reflection is detectable even in the lowest wind conditions. Further, a technique is developed to remove the environmental dependency so that the returns estimate seabed impedance.
Show PACS
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.30.Wi Passive sonar systems and algorithms, matched field processing in underwater acoustics
43.60.Pt Signal processing techniques for acoustic inverse problems

A stochastic response surface formulation of acoustic propagation through an uncertain ocean waveguide environment

Steven Finette

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2242-2247 (2009); (6 pages)

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Stochastic basis expansions are applied to formulate and solve the problem of including uncertainty in numerical models of acoustic wave propagation within ocean waveguides. As an example, a constrained least-squares approach is used to estimate the intensity of an acoustic field whose waveguide environment has uncertainty in both source depth and sound speed. The mean intensity, a second moment of the field, and its probability distribution are computed and compared with independent Monte-Carlo computations of these quantities. Very good agreement is obtained, indicating the potential of stochastic basis expansions for describing multiple sources of uncertainty and their effect on acoustic propagation.
Show PACS
43.30.Re Signal coherence or fluctuation due to sound propagation/scattering in the ocean
43.20.Bi Mathematical theory of wave propagation
43.20.Mv Waveguides, wave propagation in tubes and ducts

A large-aperture low-cost hydrophone array for tracking whales from small boats

B. Miller and S. Dawson

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2248-2256 (2009); (9 pages) | Cited 4 times

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A passive sonar array designed for tracking diving sperm whales in three dimensions from a single small vessel is presented, and the advantages and limitations of operating this array from a 6 m boat are described. The system consists of four free floating buoys, each with a hydrophone, built-in recorder, and global positioning system receiver (GPS), and one vertical stereo hydrophone array deployed from the boat. Array recordings are post-processed onshore to obtain diving profiles of vocalizing sperm whales. Recordings are synchronized using a GPS timing pulse recorded onto each track. Sensitivity analysis based on hyperbolic localization methods is used to obtain probability distributions for the whale’s three-dimensional location for vocalizations received by at least four hydrophones. These localizations are compared to those obtained via isodiachronic sequential bound estimation. Results from deployment of the system around a sperm whale in the Kaikoura Canyon in New Zealand are shown.
Show PACS
43.30.Wi Passive sonar systems and algorithms, matched field processing in underwater acoustics
43.30.Sf Acoustical detection of marine life; passive and active

Comparison of the properties of tonpilz transducers fabricated with 〈001〉 fiber-textured lead magnesium niobate-lead titanate ceramic and single crystals

Kristen H. Brosnan, Gary L. Messing, Douglas C. Markley, and Richard J. Meyer, Jr.

J. Acoust. Soc. Am. Volume 126, Issue 5, pp. 2257-2265 (2009); (9 pages)

Online Publication Date: 05 Nov 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Tonpilz transducers are fabricated from 〈001〉 fiber-textured 0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 (PMN-28PT) ceramics, obtained by the templated grain growth process, and PMN-28PT ceramic and Bridgman grown single crystals of the same composition. In-water characterization of single element transducers shows higher source levels, higher in-water coupling, and more usable bandwidth for the 81 vol % textured PMN-28PT device than for the ceramic PMN-28PT element. The 81 vol % textured PMN-28PT tonpilz element measured under large signals shows linearity in sound pressure levels up to 0.23 MV/m drive field but undergoes a phase transition due to a lowered transition temperature from the SrTiO3 template particles. Although the textured ceramic performs well in this application, it could be further improved with compositional tailoring to raise the transition temperature and better processing to improve the texture quality. With these improvements textured piezoelectric ceramics will be viable options for medical ultrasound, actuators, and sonar applications because of their ease of processing, compositional homogeneity, and potentially lower cost than single crystal.
Show PACS
43.30.Yj Transducers and transducer arrays for underwater sound; transducer calibration
43.38.Fx Piezoelectric and ferroelectric transducers
Page 1 of 6 Pages Next Page | Jump to Page
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close