• 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

May 2012

Volume 131, Issue 5, pp. EL355-4232

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

Biomechanical modeling of English /r/ variants

Ian Stavness, Bryan Gick, Donald Derrick, and Sidney Fels

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL355-EL360 (2012); (6 pages)

Online Publication Date: 09 Apr 2012

Full Text: Read Online (HTML) | Download PDF

multimedia

Show Abstract
This study reports an investigation of the well-known context-dependent variation in English /r/ using a biomechanical tongue-jaw-hyoid model. The simulation results show that preferred /r/ variants require less volume displacement, relative strain, and relative muscle stress than variants that are not preferred. This study also uncovers a previously unknown mechanism in tongue biomechanics for /r/ production: Torque in the sagittal plane about the mental spine. This torque enables raising of the tongue anterior for retroflexed [ɻ] by activation of hyoglossus and relaxation of anterior genioglossus. The results provide a deeper understanding of the articulatory factors that govern contextual phonetic variation.
Show PACS
43.70.Aj Anatomy and physiology of the vocal tract, speech aerodynamics, auditory kinetics
43.70.Bk Models and theories of speech production
FREE

A frequency bin-wise nonlinear masking algorithm in convolutive mixtures for speech segregation

Tai-Shih Chi, Ching-Wen Huang, and Wen-Sheng Chou

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL361-EL367 (2012); (7 pages)

Online Publication Date: 09 Apr 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A frequency bin-wise nonlinear masking algorithm is proposed in the spectrogram domain for speech segregation in convolutive mixtures. The contributive weight from each speech source to a time-frequency unit of the mixture spectrogram is estimated by a nonlinear function based on location cues. For each sound source, a non-binary mask is formed from the estimated weights and is multiplied to the mixture spectrogram to extract the sound. Head-related transfer functions (HRTFs) are used to simulate convolutive sound mixtures perceived by listeners. Simulation results show our proposed method outperforms convolutive independent component analysis and degenerate unmixing and estimation technique methods in almost all test conditions.
Show PACS
43.60.Gk Space-time signal processing, other than matched field processing
43.60.Hj Time-frequency signal processing, wavelets
43.60.Dh Signal processing for communications: telephony and telemetry, sound pickup and reproduction, multimedia
FREE

Spectro-temporal modulation energy based mask for robust speaker identification

Tai-Shih Chi, Ting-Han Lin, and Chung-Chien Hsu

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL368-EL374 (2012); (7 pages)

Online Publication Date: 09 Apr 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spectro-temporal modulations of speech encode speech structures and speaker characteristics. An algorithm which distinguishes speech from non-speech based on spectro-temporal modulation energies is proposed and evaluated in robust text-independent closed-set speaker identification simulations using the TIMIT and GRID corpora. Simulation results show the proposed method produces much higher speaker identification rates in all signal-to-noise ratio (SNR) conditions than the baseline system using mel-frequency cepstral coefficients. In addition, the proposed method also outperforms the system, which uses auditory-based nonnegative tensor cepstral coefficients [Q. Wu and L. Zhang, “Auditory sparse representation for robust speaker recognition based on tensor structure,” EURASIP J. Audio, Speech, Music Process. 2008, 578612 (2008)], in low SNR (≤ 10 dB) conditions.
Show PACS
43.60.Hj Time-frequency signal processing, wavelets
43.72.Ar Speech analysis and analysis techniques; parametric representation of speech
43.72.Fx Talker identification and adaptation algorithms
43.60.Bf Acoustic signal detection and classification, applications to control systems
FREE

Correlations between ultrasonic guided wave velocities and bone properties in bovine tibia in vitro

Kang Il Lee and Suk Wang Yoon

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL375-EL381 (2012); (7 pages)

Online Publication Date: 09 Apr 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Correlations between ultrasonic guided wave velocities and bone properties were investigated in bovine tibia in vitro. The velocities of the first arriving signal and the slow guided wave, termed VFAS and VSGW, along the long axis of the tibia were measured at 200 kHz in 20 bovine tibiae using the axial transmission technique. VFAS yielded significant negative correlation coefficients of −0.54 to −0.66 with the bone properties. In contrast, VSGW yielded strong positive correlation coefficients of 0.68–0.84. The best univariate predictor of VFAS and VSGW was the cortical thickness yielding adjusted squared correlation coefficients of 0.41 and 0.69, respectively.
Show PACS
43.80.Cs Acoustical characteristics of biological media: molecular species, cellular level tissues
43.80.Qf Medical diagnosis with acoustics
43.80.Vj Acoustical medical instrumentation and measurement techniques
FREE

Cochlear implant patients’ localization using interaural level differences exceeds that of untrained normal hearing listeners

Justin M. Aronoff, Daniel J. Freed, Laurel M. Fisher, Ivan Pal, and Sigfrid D. Soli

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL382-EL387 (2012); (6 pages)

Online Publication Date: 09 Apr 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Bilateral cochlear implant patients are unable to localize as well as normal hearing listeners. Although poor sensitivity to interaural time differences clearly contributes to this deficit, it is unclear whether deficits in terms of interaural level differences are also a contributing factor. In this study, localization was tested while manipulating interaural time and level cues using head-related transfer functions. The results indicate that bilateral cochlear implant users’ ability to localize based on interaural level differences is actually greater than that of untrained normal hearing listeners.
Show PACS
43.66.Pn Binaural hearing
43.66.Qp Localization of sound sources
43.66.Ts Auditory prostheses, hearing aids
FREE

A model for the spatial coherence of arbitrarily directive noise in the depth-stratified ocean

Shane C. Walker

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL388-EL394 (2012); (7 pages) | Cited 2 times

Online Publication Date: 13 Apr 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Though referred to as noise, the ambient ocean soundscape carries valuable information about the physical ocean environment. To study this information, Kuperman and Ingenito introduced a model for spatial coherence in a depth stratified ocean arising from the vertically directive diffuse acoustic noise produced by bubbles distributed throughout the surface. Here the model is adapted to incorporate horizontal directivity as well, making it possible to include additional noise contributions from directive features such as storms, biologics, shipping, and wave breaking. As an analytic approach, the model can serve as a computationally light complement to existing methods.
Show PACS
43.30.Re Signal coherence or fluctuation due to sound propagation/scattering in the ocean
43.60.Cg Statistical properties of signals and noise
43.20.Bi Mathematical theory of wave propagation
FREE

Acoustic imaging device with one transducer

Nicolas Etaix, Mathias Fink, and Ros K. Ing

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL395-EL399 (2012); (5 pages)

Online Publication Date: 13 Apr 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper presents a low profile imaging device using only one piezoelectric transducer and a microphone. The transducer is glued to an aluminum plate of non-regular geometry that acts as an acoustic cavity. Beam steering is achieved, and the acoustic waves should be focused anywhere in front of the plate. Finally, using a single microphone receiver working in echographic mode, our imaging device is able to locate any object placed in front of it.
Show PACS
43.20.Tb Interaction of vibrating structures with surrounding medium
43.20.Ye Measurement methods and instrumentation
43.40.Dx Vibrations of membranes and plates
FREE

Using feature vectors to detect frog calls in wireless sensor networks

Benjamin Croker and Navinda Kottege

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL400-EL405 (2012); (6 pages)

Online Publication Date: 13 Apr 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method for detecting vocalization of giant barred frogs (Mixophyes iteratus) in noisy audio is proposed. Audio recordings from remote wireless sensor nodes were segmented into individual sounds and from each sound a small set of features was extracted. Feature vectors were compared to those of example calls using a Euclidean distance formula as a detection system. The system achieved a sensitivity of 0.85 with specificity of 0.92 when distinguishing M. iteratus calls from other species’ calls and sensitivity of 0.88 with specificity 0.82 against background noise.
Show PACS
43.80.Jz Use of acoustic energy (with or without other forms) in studies of structure and function of biological systems
43.28.Hr Outdoor sound sources
43.60.Bf Acoustic signal detection and classification, applications to control systems
FREE

Native dialect influences second-language vowel perception: Peruvian versus Iberian Spanish learners of Dutch

Paola Escudero and Daniel Williams

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL406-EL412 (2012); (7 pages)

Online Publication Date: 18 Apr 2012

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Peruvian Spanish (PS) and Iberian Spanish (IS) learners were tested on their ability to categorically discriminate and identify Dutch vowels. It was predicted that the acoustic differences between the vowel productions of the two dialects, which compare differently to Dutch vowels, would manifest in differential L2 perception for listeners of these two dialects. The results show that although PS learners had higher general L2 proficiency, IS learners were more accurate at discriminating all five contrasts and at identifying six of the L2 Dutch vowels. These findings confirm that acoustic differences in native vowel production lead to differential L2 vowel perception.
Show PACS
43.71.Ft Development of speech perception
43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
43.71.An Models and theories of speech perception
FREE

Multibubble sonoluminescence pulses from Na atoms in viscous liquid

Pak-Kon Choi, Yosuke Sawada, and Yuuta Takeuchi

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. EL413-EL419 (2012); (7 pages)

Online Publication Date: 18 Apr 2012

Full Text: Read Online (HTML) | Download PDF

multimedia

Show Abstract
Multibubble sonoluminescence pulses of Na and continuum emissions were measured from NaCl-ethylene glycol solution saturated with Xe at 28 kHz. The Na emission consisted of multiple-peak pulses and single pulses. The intrinsic pulse width estimated from single pulses was 0.37 ns, which differs from 10–165 ns obtained by previous work. High-speed shadowgraphs of bubble dynamics and high-speed movies (32000 fps) of sonoluminescence were observed. The observations suggest that the multiple-peak pulse is due to the superposition of single peaks resulting from bubbles fragmented from a characteristic bubble which repeats the fragmentation and coalescence. This phenomenon may be specific to viscous liquids.
Show PACS
43.35.Ei Acoustic cavitation in liquids
back to top
RSS Feeds

How comparable are children and adults in perceiving an optimal tempo for music? (L)

Sandra Quinn, Oona O’Hare, and Deborah M. Riby

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3595-3598 (2012); (4 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This research compared the abilities of children and adults to perceive an optimal tempo for pieces of music. Participants heard eight melodies played at a range of tempi and made a 2AFC of “too fast” or “too slow” for each presentation. Children (aged between 5 to 11 years) and adults (aged between 17 to 54 years) showed the same variation in perceived optimal tempi across melodies. The same variation in optimal tempi was also observed when pitch variations were removed. This suggests that the rhythmical structure was responsible for the perceived optimal tempi for these pieces of music.
Show PACS
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.75.Cd Music perception and cognition
43.75.Zz Analysis, synthesis, and processing of musical sounds

Response to “Comments on ‘A field study of the exposure-annoyance relationship of military shooting noise’ ” [J. Acoust. Soc. Am. 127, 2301–2311 (2010)] (L)

Mark Brink and Jean-Marc Wunderli

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3599-3600 (2012); (2 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter is a response to Meyer’s recent paper [“Comment on ‘A field study of the exposure-annoyance relationship of military shooting noise,’ ” J. Acoust. Soc. Am. 130, 677–678 (2011)]. The authors describe that “explained variance” in noise annoyance surveys can mean different things and that the fit parameters of the statistical models reported in the commented article are well within an expectable range. It is discussed that non-dose-related factors for the prediction of noise annoyance have become increasingly important in the last years and deserve to be more thoroughly studied.
Show PACS
43.50.Qp Effects of noise on man and society
back to top
RSS Feeds

Number and location of zero-group-velocity modes

Eduardo Kausel

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3601-3610 (2012); (10 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The frequency-wavenumber spectra of laminated media often exhibit anomalous modes with descending branches whose group velocity is negative, and these terminate at a minimum point at which the group velocity transitions from negative to positive. These minima are associated with resonant conditions in the medium, which have been clearly observed in experiments and in the nondestructive testing of laminated plates. Starting from first principles, this paper provides a theoretical analysis on the number and location of such zero-group-velocity (ZGV) modes for horizontally layered media bounded by any arbitrary combination of external boundaries. It is found that these ZGV points are few in number and show up mostly in low-order modes which are characterized by a negative second derivative at the cutoff frequencies, a condition that can readily be tested. It is also shown that the effective number of ZGVs is small even when the ratio of the dilatational and shear wave velocity is a rational number and there exist coincidences in cutoff frequencies, a condition that at first would suggest that the number of ZGVs is infinite. Finally, it is shown that the number of ZGVs decreases with the Poisson’s ratio.
Show PACS
43.20.Bi Mathematical theory of wave propagation
43.40.Dx Vibrations of membranes and plates

A unified optical theorem for scalar and vectorial wave fields

Kees Wapenaar and Huub Douma

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3611-3626 (2012); (16 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The generalized optical theorem is an integral relation for the angle-dependent scattering amplitude of an inhomogeneous scattering object embedded in a homogeneous background. It has been derived separately for several scalar and vectorial wave phenomena. Here a unified optical theorem is derived that encompasses the separate versions for scalar and vectorial waves. Moreover, this unified theorem also holds for scattering by anisotropic elastic and piezoelectric scatterers as well as bianisotropic (non-reciprocal) EM scatterers.
Show PACS
43.20.Fn Scattering of acoustic waves
43.20.Gp Reflection, refraction, diffraction, interference, and scattering of elastic and poroelastic waves

Acoustic particle manipulation in a 40 kHz quarter-wavelength standing wave with an air boundary

Giuliana Trippa, Stéphanie Trine, Yiannis Ventikos, and Constantin-C. Coussios

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3627-3637 (2012); (11 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An implementation of a quarter-wavelength standing wave separator that exploits an air drum to achieve the pressure node is presented and characterized experimentally. The air drum configuration was implemented and tested in a set-up with a 40 kHz transducer immersed in a water tank with the quarter-wavelength gap being approximately 9 mm wide. Injection of suspensions of 5 μm and 45 μm diameter polystyrene particles at flow rates of 30 ml/h and 60 ml/h was studied and particle deflection towards the pressure node at the air drum surface was observed for a range of acoustic pressures. Computational results on single particle trajectories show good agreement with the experimental findings for the 45 μm particles, but not for the 5 μm particles. These were considered to behave as aggregates of higher effective dimension, due to their much higher number density relative to the 45 μm particles in the suspensions used. The set-up developed in this study includes a robust method for achieving a pressure node in a quarter-wavelength system and can represent the first step toward the development of an alternative separator configuration in respect to small channel MHz range operated systems for the manipulation of particles streams.
Show PACS
43.20.Ks Standing waves, resonance, normal modes
43.25.Gf Standing waves; resonance
43.35.Ty Other physical effects of sound

A hybrid finite element approach to modeling sound radiation from circular and rectangular ducts

Wenbo Duan and Ray Kirby

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3638-3649 (2012); (12 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A numerical model based on a hybrid finite element method is developed that seeks to join sound pressure fields in interior and exterior regions. The hybrid method is applied to the analysis of sound radiation from open pipes, or ducts, and uses mode matching to couple a finite element discretization of the region surrounding the open end of the duct to wave based modal expansions for adjoining interior and exterior regions. The hybrid method facilitates the analysis of ducts of arbitrary but uniform cross section as well the study of conical flanges and here a modal expansion based on spherical harmonics is applied. Predictions are benchmarked against analytic solutions for the limiting cases of flanged and unflanged circular ducts and excellent agreement between the two methods is observed. Predictions are also presented for flanged and unflanged rectangular ducts, and because the hybrid method retains the sparse banded and symmetric matrices of the traditional finite element method, it is shown that predictions can be obtained within an acceptable time frame even for a three dimensional problem.
Show PACS
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.El Reflection, refraction, diffraction of acoustic waves
back to top
RSS Feeds

A nodal discontinuous Galerkin finite element method for nonlinear elastic wave propagation

Olivier Bou Matar, Pierre-Yves Guerder, YiFeng Li, Bart Vandewoestyne, and Koen Van Den Abeele

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3650-3663 (2012); (14 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A nodal discontinuous Galerkin finite element method (DG-FEM) to solve the linear and nonlinear elastic wave equation in heterogeneous media with arbitrary high order accuracy in space on unstructured triangular or quadrilateral meshes is presented. This DG-FEM method combines the geometrical flexibility of the finite element method, and the high parallelization potentiality and strongly nonlinear wave phenomena simulation capability of the finite volume method, required for nonlinear elastodynamics simulations. In order to facilitate the implementation based on a numerical scheme developed for electromagnetic applications, the equations of nonlinear elastodynamics have been written in a conservative form. The adopted formalism allows the introduction of different kinds of elastic nonlinearities, such as the classical quadratic and cubic nonlinearities, or the quadratic hysteretic nonlinearities. Absorbing layers perfectly matched to the calculation domain of the nearly perfectly matched layers type have been introduced to simulate, when needed, semi-infinite or infinite media. The developed DG-FEM scheme has been verified by means of a comparison with analytical solutions and numerical results already published in the literature for simple geometrical configurations: Lamb’s problem and plane wave nonlinear propagation.
Show PACS
43.25.Dc Nonlinear acoustics of solids
43.20.Bi Mathematical theory of wave propagation
43.20.Gp Reflection, refraction, diffraction, interference, and scattering of elastic and poroelastic waves

Acoustic radiation force analysis using finite difference time domain method

A. Grinenko, P. D. Wilcox, C. R. P. Courtney, and B. W. Drinkwater

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3664-3670 (2012); (7 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Acoustic radiation force exerted by standing waves on particles is analyzed using a finite difference time domain Lagrangian method. This method allows the acoustic radiation force to be obtained directly from the solution of nonlinear fluid equations, without any assumptions on size or geometry of the particles, boundary conditions, or acoustic field amplitude. The model converges to analytical results in the limit of small particle radii and low field amplitudes, where assumptions within the analytical models apply. Good agreement with analytical and numerical models based on solutions of linear scattering problems is observed for compressible particles, whereas some disagreement is detected when the compressibility of the particles decreases.
Show PACS
43.25.Qp Radiation pressure
back to top
RSS Feeds

A model for the vertical sound speed and absorption profiles in Titan’s atmosphere based on Cassini-Huygens data

Andi Petculescu and Peter Achi

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3671-3679 (2012); (9 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Measurements of thermodynamic quantities in Titan’s atmosphere during the descent of Huygens in 2005 are used to predict the vertical profiles for the speed and intrinsic attenuation (or absorption) of sound. The calculations are done using one author’s previous model modified to accommodate non-ideal equations of state. The vertical temperature profile places the tropopause about 40 km above the surface. In the model, a binary nitrogen-methane composition is assumed for Titan’s atmosphere, quantified by the methane fraction measured by the gas chromatograph/mass spectrometer (GCMS) onboard Huygens. To more accurately constrain the acoustic wave number, the variation of thermophysical properties (specific heats, viscosity, and thermal conductivity) with altitude is included via data extracted from the NIST Chemistry WebBook [URL webbook.nist.gov, National Institute of Standards and Technology Chemistry WebBook (Last accessed 10/20/2011)]. The predicted speed of sound profile fits well inside the spread of the data recorded by Huygens’ active acoustic sensor. In the N2-dominated atmosphere, the sound waves have negligible relaxational dispersion and mostly classical (thermo-viscous) absorption. The cold and dense environment of Titan can sustain acoustic waves over large distances with relatively small transmission losses, as evidenced by the small absorption. A ray-tracing program is used to assess the bounds imposed by the zonal wind—measured by the Doppler Wind Experiment on Huygens—on long-range propagation.
Show PACS
43.28.Bj Mechanisms affecting sound propagation in air, sound speed in the air
43.20.Hq Velocity and attenuation of acoustic waves

Impulse propagation in the nocturnal boundary layer: Analysis of the geometric component

Philip Blom and Roger Waxler

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3680-3690 (2012); (11 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
On clear dry nights over flat land, a temperature inversion and stable nocturnal wind jet lead to an acoustic duct in the lowest few hundred meters of the atmosphere. An impulsive signal propagating in such a duct is received at long ranges from the source as an extended wave train consisting of a series of weakly dispersed distinct arrivals followed by a strongly dispersed low-frequency tail. The leading distinct arrivals have been previously shown to be well modeled by geometric acoustics. In this paper, the geometric acoustics approximation for the leading arrivals is investigated. Using the solutions of the eikonal and transport equations, travel times, amplitudes, and caustic structures of the distinct arrivals have been determined. The time delay between and relative amplitudes of the direct-refracted and single ground reflection arrivals have been investigated as parameters for an inversion scheme. A two parameter quadratic approximation to the effective sound speed profile has been fit and found to be in strong agreement with meteorological measurements from the time of propagation.
Show PACS
43.28.Fp Outdoor sound propagation through a stationary atmosphere, meteorological factors
43.28.Js Numerical models for outdoor propagation
43.20.Bi Mathematical theory of wave propagation
back to top
RSS Feeds

Relating waveguide invariant and bottom reflection phase-shift parameter P in a Pekeris waveguide

E. C. Shang, J. R. Wu, and Z. D. Zhao

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3691-3697 (2012); (7 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The waveguide invariant β is affected by the shallow-water environment. The effect due to bottom sediment on β is investigated in this paper. It is found that the effect of sediment bottom can be concentrated on one parameter P—the bottom reflection phase-shift parameter. For a Pekeris waveguide, under Wentzel–Kramers–Brillouin (WKB) approximation, a very simple analytic relation is given: β ≈ 1 + P/(k0Heff), where Heff is the “effective depth,” and Heff = H + P/2k0. The value of β related to different high-speed sediments (including layered sediment) ranges from 1.0 to 1.5. Some numerical examples including the layered sediment case are conducted to verify this result. Good agreement between the results calculated by KRAKEN and by WKB with parameter P has been found. Hence, the application of parameter P provides a model-free platform to investigate the bottom effect on the waveguide invariant β in shallow-water.
Show PACS
43.30.Dr Hybrid and asymptotic propagation theories, related experiments
43.30.Bp Normal mode propagation of sound in water

Range compensation for backscattering measurements in the difference-frequency nearfield of a parametric sonar

Kenneth G. Foote

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3698-3709 (2012); (12 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Measurement of acoustic backscattering properties of targets requires removal of the range dependence of echoes. This process is called range compensation. For conventional sonars making measurements in the transducer farfield, the compensation removes effects of geometrical spreading and absorption. For parametric sonars consisting of a parametric acoustic transmitter and a conventional-sonar receiver, two additional range dependences require compensation when making measurements in the nonlinearly generated difference-frequency nearfield: an apparently increasing source level and a changing beamwidth. General expressions are derived for range compensation functions in the difference-frequency nearfield of parametric sonars. These are evaluated numerically for a parametric sonar whose difference-frequency band, effectively 1–6 kHz, is being used to observe Atlantic herring (Clupea harengus) in situ. Range compensation functions for this sonar are compared with corresponding functions for conventional sonars for the cases of single and multiple scatterers. Dependences of these range compensation functions on the parametric sonar transducer shape, size, acoustic power density, and hydrography are investigated. Parametric range compensation functions, when applied with calibration data, will enable difference-frequency echoes to be expressed in physical units of volume backscattering, and backscattering spectra, including fish-swimbladder-resonances, to be analyzed.
Show PACS
43.30.Lz Underwater applications of nonlinear acoustics; explosions
43.30.Sf Acoustical detection of marine life; passive and active
43.60.Fg Acoustic array systems and processing, beam-forming
43.80.Jz Use of acoustic energy (with or without other forms) in studies of structure and function of biological systems

Improving riverbed sediment classification using backscatter and depth residual features of multi-beam echo-sounder systems

Dimitrios Eleftherakis, AliReza Amiri-Simkooei, Mirjam Snellen, and Dick G. Simons

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3710-3725 (2012); (16 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Riverbed and seafloor sediment classification using acoustic remote sensing techniques is of high interest due to their high coverage capabilities at limited cost. This contribution presents the results of riverbed sediment classification using multi-beam echo-sounder data based on an empirical method. Two data sets are considered, both taken at the Waal River, namely Sint Andries and Nijmegen. This work is a follow-up to the work carried out by Amiri-Simkooei et al. [J. Acoust. Soc. Am. 126(4), 1724–1738 (2009)]. The empirical method bases the classification on features of the backscatter strength and depth residuals. A principal component analysis is used to identify the most appropriate and informative features. Clustering is then applied to the principal components resulting from this set of features to assign a sediment class to each measurement. The results show that the backscatter strength features discriminate between different classes based on the sediment properties, whereas the depth residual features discriminate classes based on riverbed forms such as the “fixed layer” (stone having riprap structure) and riverbed ripples. Combination of these two sets of features is highly recommended because they provide complementary information on both the composition and the structure of the riverbed.
Show PACS
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography

Automated detection and localization of bowhead whale sounds in the presence of seismic airgun surveys

Aaron M. Thode, Katherine H. Kim, Susanna B. Blackwell, Charles R. Greene, Jr., Christopher S. Nations, Trent L. McDonald, and A. Michael Macrander

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3726-3747 (2012); (22 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An automated procedure has been developed for detecting and localizing frequency-modulated bowhead whale sounds in the presence of seismic airgun surveys. The procedure was applied to four years of data, collected from over 30 directional autonomous recording packages deployed over a 280 km span of continental shelf in the Alaskan Beaufort Sea. The procedure has six sequential stages that begin by extracting 25-element feature vectors from spectrograms of potential call candidates. Two cascaded neural networks then classify some feature vectors as bowhead calls, and the procedure then matches calls between recorders to triangulate locations. To train the networks, manual analysts flagged 219 471 bowhead call examples from 2008 and 2009. Manual analyses were also used to identify 1.17 million transient signals that were not whale calls. The network output thresholds were adjusted to reject 20% of whale calls in the training data. Validation runs using 2007 and 2010 data found that the procedure missed 30%–40% of manually detected calls. Furthermore, 20%–40% of the sounds flagged as calls are not present in the manual analyses; however, these extra detections incorporate legitimate whale calls overlooked by human analysts. Both manual and automated methods produce similar spatial and temporal call distributions.
Show PACS
43.30.Sf Acoustical detection of marine life; passive and active
43.60.Np Acoustic signal processing techniques for neural nets and learning systems
43.30.Wi Passive sonar systems and algorithms, matched field processing in underwater acoustics
43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms

A spiral wave front beacon for underwater navigation: Transducer prototypes and testing

Benjamin R. Dzikowicz and Brian T. Hefner

J. Acoust. Soc. Am. Volume 131, Issue 5, pp. 3748-3754 (2012); (7 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Transducers for acoustic beacons which can produce outgoing signals with wave fronts whose horizontal cross sections are circular or spiral are studied experimentally. A remote hydrophone is used to determine its aspect relative to the transducers by comparing the phase of the circular signal to the phase of the spiral signal. The transducers for a “physical-spiral” beacon are made by forming a strip of 1–3 piezocomposite transducer material around either a circular or spiral backing. A “phased-spiral” beacon is made from an array of transducer elements which can be driven either in phase or staggered out of phase so as to produce signals with either a circular or spiral wave front. Measurements are made to study outgoing signals and their usefulness in determining aspect angle. Vertical beam width is also examined and phase corrections applied when the hydrophone is out of the horizontal plane of the beacon. While numerical simulations indicate that the discontinuity in the physical-spiral beacon introduces errors into the measured phase, damping observed at the ends of the piezocomposite material is a more significant source of error. This damping is also reflected in laser Doppler vibrometer measurements of the transducer’s surface velocity.
Show PACS
43.30.Tg Navigational instruments using underwater sound
43.30.Yj Transducers and transducer arrays for underwater sound; transducer calibration
43.38.Hz Transducer arrays, acoustic interaction effects in arrays
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