• 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

Feb 2009

Volume 125, Issue 2, pp. EL51-1267

Page 1 of 5 Pages Next Page | Jump to Page
back to top
RSS Feeds
FREE

A generalized Cramér-Rao lower bound for moving arrays

Edmund J. Sullivan

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. EL51-EL57 (2009); (7 pages) | Cited 1 time

Online Publication Date: 21 Jan 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
By properly including the forward motion of the array in the signal model, improved bearing estimation performance for a towed line array can be obtained. The improvement is a consequence of utilizing the bearing information contained in the Doppler. In this paper, it is shown by use of the Cramér-Rao lower bound that, as the array moves forward, the variance on the bearing estimate for an array of pressure sensors decreases, and that if an array of pressure-vector sensors is used, a significant improvement over that obtained for the array using pressure sensors only is obtained.
Show PACS
43.60.Fg Acoustic array systems and processing, beam-forming
43.30.Wi Passive sonar systems and algorithms, matched field processing in underwater acoustics
FREE

Melody recognition by two-month-old infants

Judy Plantinga and Laurel J. Trainor

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. EL58-EL62 (2009); (5 pages)

Online Publication Date: 21 Jan 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Music is part of an infant’s world even before birth, and caregivers around the world sing to infants. Yet, there has been little research into the musical abilities or preferences of infants younger than 5 months. In this study, the head turn preference procedure used with older infants was adapted into an eye-movement preference procedure so that the ability of 2-month-old infants to remember a short melody could be tested. The results show that with minimal familiarization, 2-month-old infants remember a short melody and can discriminate it from a similar melody.
Show PACS
43.75.Cd Music perception and cognition
43.66.Hg Pitch
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Lj Perceptual effects of sound
FREE

Transient motion of a circular plate after an impact

Thomas R. Moore, Daniel W. Zietlow, Christopher W. Gorman, Donald C. Griffin, Connor P. Ballance, and David J. Parker

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. EL63-EL69 (2009); (7 pages)

Online Publication Date: 21 Jan 2009

Full Text: Read Online (HTML) | Download PDF

multimedia

Show Abstract
The transient response of a flat circular plate to a sudden impact has been studied experimentally and theoretically. High-speed electronic speckle pattern interferometry reveals the presence of pulses that travel around the edge of the plate ahead of the bending motion initiated by the strike. It is found that the transient motion of the plate is well described by Kirchhoff thin-plate theory over a time approximately equal to the time required for the initial impulse to circumvent the plate; however, a more sophisticated model is required to describe the motion after this time has elapsed.
Show PACS
43.40.Kd Impact and impact reduction, mechanical transients
43.40.At Experimental and theoretical studies of vibrating systems
43.40.Dx Vibrations of membranes and plates
FREE

Lanczos iterated time-reversal

Assad A. Oberai, Gonzalo R. Feijóo, and Paul E. Barbone

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. EL70-EL76 (2009); (7 pages)

Online Publication Date: 21 Jan 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A new iterative time-reversal algorithm capable of identifying and focusing on multiple scatterers in a relatively small number of iterations is developed. It is recognized that the traditional iterated time-reversal method is based on utilizing power iterations to determine the dominant eigenpairs of the time-reversal operator. The convergence properties of these iterations are known to be suboptimal. Motivated by this, a new method based on Lanczos iterations is developed. In several illustrative examples it is demonstrated that for the same number of transmitted and received signals, the Lanczos iterations based approach is substantially more accurate.
Show PACS
43.60.Tj Wave front reconstruction, acoustic time-reversal, and phase conjugation
43.20.-f General linear acoustics
43.60.Lq Acoustic imaging, displays, pattern recognition, feature extraction
FREE

Effect of bandwidth extension to telephone speech recognition in cochlear implant users

Chuping Liu, Qian-Jie Fu, and Shrikanth S. Narayanan

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. EL77-EL83 (2009); (7 pages) | Cited 1 time

Online Publication Date: 21 Jan 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The present study investigated a bandwidth extension method to enhance telephone speech understanding for cochlear implant (CI) users. The acoustic information above telephone speech transmission range (i.e., 3400 Hz) was estimated based on trained models describing the relation between narrow-band and wide-band speech. The effect of the bandwidth extension method was evaluated with IEEE sentence recognition tests in seven CI users. Results showed a relatively modest but significant improvement in the speech recognition with the proposed method. The effect of bandwidth extension method was also observed to be highly dependent on individual CI users.
Show PACS
43.71.Ky Speech perception by the hearing impaired
43.64.Me Effects of electrical stimulation, cochlear implant
43.60.Dh Signal processing for communications: telephony and telemetry, sound pickup and reproduction, multimedia
back to top
RSS Feeds

Extensional edge modes in elastic plates and shells

J. Kaplunov, A. V. Pichugin, and V. Zernov

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 621-623 (2009); (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The recently discovered undamped localized mode at the end of an elastic strip is demonstrated to be particularly relevant in the plane stress setting, where it exists for the Poisson ratio 0.29. This paper also emphasizes the difference between low-frequency edge modes, typically characterized by low variation across the plate (or shell) thickness, and high-frequency edge modes, whose natural frequencies are of the order of thickness resonance frequencies.
Show PACS
43.40.Dx Vibrations of membranes and plates
43.40.Ey Vibrations of shells
43.20.Ks Standing waves, resonance, normal modes

An acoustic survey of beaked whales at Cross Seamount near Hawaii

Mark A. McDonald, John A. Hildebrand, Sean M. Wiggins, David W. Johnston, and Jeffrey J. Polovina

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 624-627 (2009); (4 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An acoustic record from Cross Seamount, southwest of Hawaii, revealed sounds characteristic of beaked whale echolocation at the same relative abundance year-around (270 of 356 days), occurring almost entirely at night. The most common sound had a linear frequency upsweep from 35 to 100 kHz (the bandwidth of recording), an interpulse interval of 0.11 s, and duration of at least 932 μs. A less common upsweep sound with shorter interpulse interval and slower sweep rate was also present. Sounds matching Cuvier’s beaked whale were not detected, and Blainville’s beaked whale sounds were detected on only one occasion.
Show PACS
43.30.Sf Acoustical detection of marine life; passive and active
43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar

Trapping of shear acoustic waves by a near-surface distribution of cavities

C. Aristégui, A. L. Shuvalov, O. Poncelet, and M. Caleap

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 628-631 (2009); (4 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
For a halfspace containing random and uniform distribution of empty cylindrical cavities within finite depth beneath the surface, the dispersion spectrum of coherent shear horizontal waves is calculated and analyzed based on the effective-medium approach. The scattering-induced dispersion and attenuation are coupled with the effect of a surface waveguide filled with scatterers. As a result, the obtained spectrum bears certain essential particularities in comparison with the standard Love-wave pattern. Simple analytical estimates enable a direct evaluation of the concentration of scatterers from the dispersion data.
Show PACS
43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants

Validation of theoretical models of phonation threshold pressure with data from a vocal fold mechanical replica

Jorge C. Lucero, Annemie Van Hirtum, Nicolas Ruty, Julien Cisonni, and Xavier Pelorson

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 632-635 (2009); (4 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper analyzes the capability of a mucosal wave model of the vocal fold to predict values of phonation threshold lung pressure. Equations derived from the model are fitted to pressure data collected from a mechanical replica of the vocal folds. The results show that a recent extension of the model to include an arbitrary delay of the mucosal wave in its travel along the glottal channel provides a better approximation to the data than the original version of the model, which assumed a small delay. They also show that modeling the vocal tract as a simple inertive load, as has been proposed in recent analytical studies of phonation, fails to capture the effect of the vocal tract on the phonation threshold pressure with reasonable accuracy.
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
43.70.Jt Instrumentation and methodology for speech production research

Vowel-to-vowel coarticulation in Japanese: The effect of consonant duration

Anders Löfqvist

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 636-639 (2009); (4 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper examines vowel-to-vowel lingual coarticulation in sequences of vowel-bilabial consonant-vowel, where the duration of the oral closure for the consonant is either long or short. Native speakers of Japanese served as subjects. The linguistic material consisted of Japanese word pairs that only differed in the duration of the labial consonant, which was either long or short. Recordings were made of lip and tongue movements using a magnetometer system. It was hypothesized that there would be greater vowel-to-vowel coarticulation in the context of a short consonant, since a long consonant would allow the tongue more time to move. The overall results do not show any strong support for this hypothesis, however. Subjects modulate the speed of the tongue movement between the two vowels, making it slower during the long than during the short consonant.
Show PACS
43.70.Bk Models and theories of speech production
43.70.Aj Anatomy and physiology of the vocal tract, speech aerodynamics, auditory kinetics
back to top
RSS Feeds

The direct simulation of acoustics on Earth, Mars, and Titan

Amanda D. Hanford and Lyle N. Long

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 640-650 (2009); (11 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
With the recent success of the Huygens lander on Titan, a moon of Saturn, there has been renewed interest in further exploring the acoustic environments of the other planets in the solar system. The direct simulation Monte Carlo (DSMC) method is used here for modeling sound propagation in the atmospheres of Earth, Mars, and Titan at a variety of altitudes above the surface. DSMC is a particle method that describes gas dynamics through direct physical modeling of particle motions and collisions. The validity of DSMC for the entire range of Knudsen numbers (Kn), where Kn is defined as the mean free path divided by the wavelength, allows for the exploration of sound propagation in planetary environments for all values of Kn. DSMC results at a variety of altitudes on Earth, Mars, and Titan including the details of nonlinearity, absorption, dispersion, and molecular relaxation in gas mixtures are given for a wide range of Kn showing agreement with various continuum theories at low Kn and deviation from continuum theory at high Kn. Despite large computation time and memory requirements, DSMC is the method best suited to study high altitude effects or where continuum theory is not valid.
Show PACS
43.28.Bj Mechanisms affecting sound propagation in air, sound speed in the air
43.28.Js Numerical models for outdoor propagation
43.35.Ae Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in gases

Mesoscale variations in acoustic signals induced by atmospheric gravity waves

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

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 651-663 (2009); (13 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The results of acoustic tomographic monitoring of the coherent structures in the lower atmosphere and the effects of these structures on acoustic signal parameters are analyzed in the present study. From the measurements of acoustic travel time fluctuations (periods 1 min–1 h) with distant receivers, the temporal fluctuations of the effective sound speed and wind speed are retrieved along different ray paths connecting an acoustic pulse source and several receivers. By using a coherence analysis of the fluctuations near spatially distanced ray turning points, the internal wave-associated fluctuations are filtered and their spatial characteristics (coherences, horizontal phase velocities, and spatial scales) are estimated. The capability of acoustic tomography in estimating wind shear near ground is shown. A possible mechanism describing the temporal modulation of the near-ground wind field by ducted internal waves in the troposphere is proposed.
Show PACS
43.28.Gq Outdoor sound propagation and scattering in a turbulent atmosphere, and in non-uniform flow fields
43.28.Dm Infrasound and acoustic-gravity waves
43.28.Bj Mechanisms affecting sound propagation in air, sound speed in the air
43.60.Rw Remote sensing methods, acoustic tomography

Broadband impedance boundary conditions for the simulation of sound propagation in the time domain

Jonghoon Bin, M. Yousuff Hussaini, and Soogab Lee

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 664-675 (2009); (12 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An accurate and practical surface impedance boundary condition in the time domain has been developed for application to broadband-frequency simulation in aeroacoustic problems. To show the capability of this method, two kinds of numerical simulations are performed and compared with the analytical/experimental results: one is acoustic wave reflection by a monopole source over an impedance surface and the other is acoustic wave propagation in a duct with a finite impedance wall. Both single-frequency and broadband-frequency simulations are performed within the framework of linearized Euler equations. A high-order dispersion-relation-preserving finite-difference method and a low-dissipation, low-dispersion Runge–Kutta method are used for spatial discretization and time integration, respectively. The results show excellent agreement with the analytical/experimental results at various frequencies. The method accurately predicts both the amplitude and the phase of acoustic pressure and ensures the well-posedness of the broadband time-domain impedance boundary condition.
Show PACS
43.28.Js Numerical models for outdoor propagation
43.28.En Interaction of sound with ground surfaces, ground cover and topography, acoustic impedance of outdoor surfaces
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods

Transition scattering in stochastically inhomogeneous media

V. Pavlov and E. P. Tito

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 676-689 (2009); (14 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
When a physical object (“a source”) without its own eigenfrequency moves through an acoustically homogeneous medium, the only possible form of acoustic radiation is the emission of Mach shock waves, which appear when the source velocity surpasses sonic speed. In nonhomogeneous media, in nonstationary media, or in the neighborhood of such media, the source motion is accompanied by the so-called “transition” radiation (diffraction or scattering), which has place even when the source moves with subsonic velocity. Key features pertaining to the formation of the acoustical transition scattering in media with fluctuating acoustical parameters are established. To analytically study the effect, the Green’s function method formulated in terms of functional derivatives is used. The relationship between the wave number and frequency, k = k(ω), for acoustic waves is found. The results serve to determine the phasing conditions necessary for opening the transition scattering and Cherenkov radiation channel and to establish the physical explanation for the phenomenon—scattering (transformation) on inhomogeneities of the accompanied source field; i.e., formation of radiation appears when the attached field readjusts back to the equilibrium state after being deformed while passing through the fluctuations of the medium.
Show PACS
43.28.Ra Generation of sound by fluid flow, aerodynamic sound and turbulence
43.28.Mw Shock and blast waves, sonic boom
43.20.Bi Mathematical theory of wave propagation
43.20.Px Transient radiation and scattering

Inversion of spinning sound fields

Michael Carley

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 690-697 (2009); (8 pages) | Cited 2 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method is presented for the reconstruction of rotating monopole source distributions using acoustic pressures measured on a sideline parallel to the source axis. The method requires no a priori assumptions about the source other than that its strength at the frequency of interest varies sinusoidally in azimuth on the source disk so that the radiated acoustic field is composed of a single circumferential mode. When multiple azimuthal modes are present, the acoustic field can be decomposed into azimuthal modes and the method applied to each mode in sequence. The method proceeds in two stages, first finding an intermediate line source derived from the source distribution and then inverting this line source to find the radial variation in source strength. A far-field form of the radiation integrals is derived, showing that the far-field pressure is a band-limited Fourier transform of the line source, establishing a limit on the quality of source reconstruction, which can be achieved using far-field measurements. The method is applied to simulated data representing wind-tunnel testing of a ducted rotor system (tip Mach number of 0.74) and to control of noise from an automotive cooling fan (tip Mach number of 0.14), studies which have appeared in the literature of source identification.
Show PACS
43.28.We Measurement methods and instrumentation for remote sensing and for inverse problems
43.50.Nm Aerodynamic and jet noise
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
back to top
RSS Feeds

Inferring the acoustic dead-zone volume by split-beam echo sounder with narrow-beam transducer on a noninertial platform

Ruben Patel, Geir Pedersen, and Egil Ona

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 698-705 (2009); (8 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Acoustic measurement of near-bottom fish with a directional transducer is generally problematical because the powerful bottom echo interferes with weaker echoes from fish within the main lobe but at greater ranges than that of the bottom. The volume that is obscured is called the dead zone. This has already been estimated for the special case of a flat horizontal bottom when observed by an echo sounder with a stable vertical transducer beam [ Ona, E., and Mitson, R. B. (1996). ICES J. Mar. Sci. 53, 677–690 ]. The more general case of observation by a split-beam echo sounder with a transducer mounted on a noninertial platform is addressed here. This exploits the capability of a split-beam echo sounder to measure the bottom slope relative to the beam axis and thence to allow the dead-zone volume over a flat but sloping bottom to be estimated analytically. The method is established for the Simrad EK60 scientific echo sounder, with split-beam transducers operating at 18, 38, 70, 120, and 200 kHz. It is validated by comparing their estimates of seafloor slope near the Lofoten Islands, N67-70, with simultaneous measurements made by two hydrographic multibeam sonars, the Simrad EM1002/95 kHz and EM300/30 kHz systems working in tandem.
Show PACS
43.30.Ft Volume scattering
43.30.Gv Backscattering, echoes, and reverberation in water due to combinations of boundaries
43.30.Sf Acoustical detection of marine life; passive and active

Model selection and Bayesian inference for high-resolution seabed reflection inversion

Jan Dettmer, Stan E. Dosso, and Charles W. Holland

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 706-716 (2009); (11 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper applies Bayesian inference, including model selection and posterior parameter inference, to inversion of seabed reflection data to resolve sediment structure at a spatial scale below the pulse length of the acoustic source. A practical approach to model selection is used, employing the Bayesian information criterion to decide on the number of sediment layers needed to sufficiently fit the data while satisfying parsimony to avoid overparametrization. Posterior parameter inference is carried out using an efficient Metropolis–Hastings algorithm for high-dimensional models, and results are presented as marginal-probability depth distributions for sound velocity, density, and attenuation. The approach is applied to plane-wave reflection-coefficient inversion of single-bounce data collected on the Malta Plateau, Mediterranean Sea, which indicate complex fine structure close to the water-sediment interface. This fine structure is resolved in the geoacoustic inversion results in terms of four layers within the upper meter of sediments. The inversion results are in good agreement with parameter estimates from a gravity core taken at the experiment site.
Show PACS
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.30.Ma Acoustics of sediments; ice covers, viscoelastic media; seismic underwater acoustics
43.60.Pt Signal processing techniques for acoustic inverse problems

Comparison of focalization and marginalization for Bayesian tracking in an uncertain ocean environment

Stan E. Dosso and Michael J. Wilmut

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 717-722 (2009); (6 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper compares focalization and marginalization approaches to source tracking when uncertain ocean environmental parameters are included, in addition to source locations, in a Bayesian inversion formulation. Focalization consists of determining the source track that maximizes the posterior probability density (PPD) over all source and environmental parameters. An efficient focalization approach is developed by applying the Viterbi algorithm to compute the optimal track from range-depth conditional probability distributions for each realization of the environmental parameters. This allows source locations to be treated implicitly and the optimization to be applied only to environmental parameters, substantially reducing the dimensionality and complexity of the problem. Marginalization consists of first integrating the PPD over the environmental unknowns to obtain a sequence of joint marginal probability distributions over source range and depth along the track. Applying the Viterbi algorithm to these marginal distributions defines the track estimate, and the distributions themselves quantify the track uncertainty. Monte Carlo analysis of the two approaches for a test case involving both geoacoustic and water-column uncertainties indicates that marginalization provides a significantly more reliable approach to tracking in an unknown environment.
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

Green's function approximation from cross-correlations of 20–100 Hz noise during a tropical storm

Laura A. Brooks and Peter Gerstoft

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 723-734 (2009); (12 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Approximation of Green’s functions through cross-correlation of acoustic signals in the ocean, a method referred to as ocean acoustic interferometry, is potentially useful for estimating parameters in the ocean environment. Travel times of the main propagation paths between hydrophone pairs were estimated from interferometry of ocean noise data that were collected on three L-shaped arrays off the New Jersey coast while Tropical Storm Ernesto passed nearby. Examination of the individual noise spectra and their mutual coherence reveals that the coherently propagating noise is dominated by signals of less than 100 Hz. Several time and frequency noise normalization techniques were applied to the low frequency data in order to determine the effectiveness of each technique for ocean acoustic applications. Travel times corresponding to the envelope peaks of the noise cross-correlation time derivatives of data were extracted from all three arrays, and are shown to be in agreement with the expected direct, surface-reflected, and surface-bottom-reflected interarray hydrophone travel times. The extracted Green’s function depends on the propagating noise. The Green’s function paths that propagate horizontally are extracted from long distance shipping noise, and during the storm the more vertical paths are extracted from breaking waves.
Show PACS
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.60.Fg Acoustic array systems and processing, beam-forming
43.30.Nb Noise in water; generation mechanisms and characteristics of the field

Range-dependent geoacoustic inversion of vertical line array data using matched beam processing

Kyungseop Kim, Woojae Seong, Keunhwa Lee, Seongil Kim, and Taebo Shim

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 735-745 (2009); (11 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper describes the results of range-dependent geoacoustic inversion using vertical line array data obtained from the 4th Matched Acoustic Properties and Localization Experiment conducted in the East Sea of Korea. The narrowband multitone continuous-wave signal from the towed source was analyzed to estimate the range-dependent geoacoustic properties along the radial track. The primary approach is based on the sectorwise inversion scheme. The inversion region up to 7.5 km from the vertical line array was divided into several segments, and the subinversions for each segment were performed sequentially. To reduce the dominance of low-angle arrivals, which bears little information for the bottom segment in question, matched beam processing with beam filtering was used for the cost function. The performance of proposed algorithm was tested using simulated data for an environment representative of the experimental site. The inversion results for the experimental data were consistent with the geophysical database and were validated from matched-field source localization using frequencies different from those used in the inversion.
Show PACS
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.60.Pt Signal processing techniques for acoustic inverse problems

Tracking of geoacoustic parameters using Kalman and particle filters

Caglar Yardim, Peter Gerstoft, and William S. Hodgkiss

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 746-760 (2009); (15 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper incorporates tracking techniques such as the extended Kalman, unscented Kalman, and particle (PF) filters into geoacoustic inversion problems. This enables spatial and temporal tracking of environmental parameters and their underlying probability densities, making geoacoustic tracking a natural extension to geoacoustic inversion techniques. Water column and seabed properties are tracked in simulation for both vertical (VLA) and horizontal (HLA) line arrays using the three tracking filters. Filter performances are compared in terms of filter efficiencies using the posterior Cramér–Rao lower bound. Tracking capabilities of the geoacoustic filters under slowly and quickly changing environments are studied in terms of divergence statistics. Geoacoustic tracking can provide continuously environmental estimates and their uncertainties using only a fraction of the computational power of classical geoacoustic inversion schemes. Interfilter comparison show that while a high-particle-number PF outperforms the Kalman filters, there are many cases where all three filters perform equally well depending on the inversion configuration (such as the HLA versus VLA and frequency) and the tracked parameters.
Show PACS
43.30.Pc Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography
43.60.Pt Signal processing techniques for acoustic inverse problems
43.60.Wy Non-stationary signal analysis, non-linear systems, and higher order statistics
back to top
RSS Feeds

Blind inversion method using Lamb waves for the complete elastic property characterization of anisotropic plates

J. Vishnuvardhan, C. V. Krishnamurthy, and Krishnan Balasubramaniam

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 761-771 (2009); (11 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A novel blind inversion method using Lamb wave S0 and A0 mode velocities is proposed for the complete determination of elastic moduli, material symmetries, as well as principal plane orientations of anisotropic plates. The approach takes advantage of genetic algorithm, introduces the notion of “statistically significant” elastic moduli, and utilizes their sensitivities to velocity data to reconstruct the elastic moduli. The unknown material symmetry and the principal planes are then evaluated using the method proposed by Cowin and Mehrabadi [Q. J. Mech. Appl. Math. 40, 451–476 (1987)] . The blind inversion procedure was verified using simulated ultrasonic velocity data sets on materials with transversely isotropic, orthotropic, and monoclinic symmetries. A modified double ring configuration of the single transmitter and multiple receiver compact array was developed to experimentally validate the blind inversion approach on a quasi-isotropic graphite-epoxy composite plate. This technique finds application in the area of material characterization and structural health monitoring of anisotropic platelike structures.
Show PACS
43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
43.38.Hz Transducer arrays, acoustic interaction effects in arrays
43.40.Le Techniques for nondestructive evaluation and monitoring, acoustic emission
43.40.Sk Inverse problems in structural acoustics and vibration

Reflection of plane elastic waves in tetragonal crystals with strong anisotropy

Vitaly B. Voloshinov, Nataliya V. Polikarpova, and Nico F. Declercq

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 772-779 (2009); (8 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Propagation and reflection of plane elastic waves in the acousto-optic crystals tellurium dioxide, rutile, barium titanate, and mercury halides are examined in the paper. The reflection from a free and flat boundary separating the crystals and the vacuum is investigated in the (001) planes in the case of glancing acoustic incidence on the boundary. The analysis shows that two bulk elastic waves may be reflected from the crystal surface. The energy flow of one of the reflected waves in paratellurite and in the mercury compounds propagates in a quasi-back-direction with respect to the incident energy flow. It is proved that energy flows of the incident and reflected elastic waves are separated by a narrow angle of only a few degrees. It is also found that the relative intensity of the unusually reflected waves is close to a unit in a wide variety of crystal cuts. General conclusions related to acoustic propagation and reflection in crystals have been made based on the examined phenomena in the materials.
Show PACS
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
43.20.El Reflection, refraction, diffraction of acoustic waves

Experimental evaluation of the acoustic properties of stacked-screen regenerators

Yuki Ueda, Toshihito Kato, and Chisachi Kato

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 780-786 (2009); (7 pages) | Cited 2 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The experimental evaluation of the wave number and characteristic impedance of stacked-screen regenerators is described. First, a two-by-two transfer matrix of a stacked-screen regenerator was estimated from pressure measurements performed at four different positions; then, the wave number and characteristic impedance of the regenerator were evaluated using a “capillary-tube-based” theory that models a stacked-screen regenerator as an array of pores having a uniform cross section. The evaluation was applied to seven types of stacked-screen regenerators. The experimental results show that these stacked-screen regenerators can be modeled as arrays of circular-cross-section tubes. Moreover, an empirical equation used to estimate the radius of the circular cross section of the tubes comprising the modeled stacked-screen regenerators was addressed.
Show PACS
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect
43.20.Mv Waveguides, wave propagation in tubes and ducts

Helmholtz-like resonators for thermoacoustic prime movers

Bonnie J. Andersen and Orest G. Symko

J. Acoust. Soc. Am. Volume 125, Issue 2, pp. 787-792 (2009); (6 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In a thermoacoustic prime mover, high acoustic output power can be achieved with a large-diameter stack and with a cavity with a large volume attached at the open end of the resonator containing the stack. The combination of resonator and cavity makes the device Helmholtz-like, with special characteristics of the resonant frequencies and quality factor, Q. Analysis of its acoustic behavior based on a model of a closed bottle presents features that are useful for the development of such prime movers for energy conversion from heat to sound. In particular, the arrangement produces in the cavity a high sound level, which is determined by the Q of the system. Comparison with a half-wave resonator type of prime mover, closed at both ends, shows the advantages of the Helmholtz-like device.
Show PACS
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect
43.25.Gf Standing waves; resonance
43.40.At Experimental and theoretical studies of vibrating systems
Page 1 of 5 Pages Next Page | Jump to Page
Close

Your Recent History Recent History Help

Recently Viewed

  1. Correction techniques for the truncation of the source field in acoustic analogies
  2. Source localization from an elevated acoustic sensor array in a refractive atmosphere
  3. On the dynamic viscous permeability tensor symmetry
  4. Multichannel array diagnosis using noise cross-correlation
  5. Historical perspectives and ongoing developments in telematic performances.

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close