Volume 124, Issue 4, October 2008
- jasa express letters
- acoustical news—usa
- acoustical news—international
- book reviews
- reviews of acoustical patents
- letters to the editor
- general linear acoustics 
- nonlinear acoustics 
- aeroacoustics, atmospheric sound 
- underwater sound 
- ultrasonics, quantum acoustics, and physical effects of sound 
- transduction 
- structural acoustics and vibration 
- noise: its effects and control 
- acoustical measurements and instrumentation 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech production 
- speech perception 
- music and musical instruments 
- bioacoustics 
- program abstracts of the 156th meeting of the acoustical society of america
- award encomiums
- program abstracts of the 156th meeting of the acoustical society of america
Index of content:
- JASA EXPRESS LETTERS
124(2008); http://dx.doi.org/10.1121/1.2960937View Description Hide Description
Using only ocean ambient noise recordings it is possible to approximate the local time domain Green’s function (TDGF) and extract the time delays associated with different ray path between the elements of a bottom hydrophone array. Comparing the strength of the noisecorrelation function taken over increasing time windows with residual fluctuations points to an optimum time window to use in the noisecorrelation function. Through comparison with computer simulations the resulting time series is shown to accurately approximate noise responses in the environment. Analysis of the TDGF gives accurate environmental detail, specifically the critical angle at the water-sediment interface.
124(2008); http://dx.doi.org/10.1121/1.2961171View Description Hide Description
Because of interactions between the signal processing and acoustic input, cochlear implant(CI) users’ melodicpitch perception may be influenced by instrument timbre. In the present study, CI listeners’ melodic contour identification was measured for six instruments (organ, glockenspiel, trumpet, clarinet, violin, and piano). While performance was generally best with the organ and poorest with the piano, individual CI subjects exhibited different patterns of results across instruments. CI subjects with the most music experience were less susceptible to timbre effects, suggesting that music training may help less experienced CI users extract melodicpitch from a variety of sound sources.
124(2008); http://dx.doi.org/10.1121/1.2968297View Description Hide Description
The current work describes a modified time-of-flight ultrasound signal processing technique applied to the study of a distal liquid layer with a free surface. The technique simulates multiple reflections analytically and determines the film thickness by comparison to the measured pulse echo signal. The technique is applied with transducers to an -pentane film condensing on a copper plate. The technique proved capable of measuring liquid thickness from approximately , the acoustic wavelength in pentane, to greater than . Near the lower thickness limit, echoes from the liquid/vapor interface overlap each other and the significantly larger echoes from the metal/liquid interface.
124(2008); http://dx.doi.org/10.1121/1.2968298View Description Hide Description
A practical application of noise cross-correlation for the diagnosis of a multichannel oceanhydrophone array is derived. Acoustic data were recorded on a horizontal line array on the New Jersey Shelf while Tropical Storm Ernesto passed through. Results obtained from active source measurements reveal that signals from several hydrophones, which were recorded on certain channels before the storm, are recorded on different channels after the storm.Noise cross-correlation of data recorded during the storm show when, and in what manner, these changes took place.
124(2008); http://dx.doi.org/10.1121/1.2968300View Description Hide Description
Based on a direct generalization of a proof given by Torquato for symmetry property in static regime, this express letter clarifies the reasons why the dynamic permeability tensor is symmetric for spatially periodic structures having symmetrical axes which do not coincide with orthogonal pairs being perpendicular to the axis of three-, four-, and sixfold symmetry. This somewhat nonintuitive property is illustrated by providing detailed numerical examples for a hexagonal lattice of solid cylinders in the asymptotic and frequency dependent regimes. It may be practically useful for numerical implementation validation and∕or convergence assessment.
A mode-based technique for estimating uncertainty in range-averaged transmission loss results from underwater acoustic calculations124(2008); http://dx.doi.org/10.1121/1.2968301View Description Hide Description
The equivalence of range and frequency averaging of acoustic propagationmodel results, based on the similarity of their analytic forms in mode calculations, was shown by Harrison [J. Acoust. Soc. Am.97, 1314–1317 (1995)]. Here it is shown how oceanographicmeasurement errors and receiver bandwidth can be mapped into uncertainty in the number of modes being propagated. This can be mapped into range boundaries for averaging calculations, thereby giving upper and lower confidence boundaries for frequency-averaged transmission loss calculations. Examples of the application of this technique to synthetic data, where the measurementuncertainties are known and deliberately included, are shown.
124(2008); http://dx.doi.org/10.1121/1.2968302View Description Hide Description
This study examined the costs of simultaneously monitoring two frequency regions. Listeners detected low- and high-frequency tones in a 2I4AFC procedure. On every trial, each signal was presented in either the first or second interval independently. Comparison of thresholds in single- and dual-signal conditions provided an estimate of the costs. Thresholds were obtained in quiet, in notched-filtered noise, and in randomized multitone maskers. No cost was found in quiet, whereas large costs were found for the masked conditions, especially for the multitone masker. These results suggest that costs of dividing attention in frequency depend on both signal and nonsignal channels.
124(2008); http://dx.doi.org/10.1121/1.2968303View Description Hide Description
Algorithm and code are presented which solve the dispersionequation for cylindrical poroelastic structures. The algorithm is based on the spectral method, which discretizes the underlying wave equations with the help of spectral differentiation matrices and solves the corresponding equations as a generalized eigenvalue problem. The results are illustrated for the case of a fluid-saturated free cylinder with open- and closed-pore boundary conditions on its surface. The computed dispersion curves are in good agreement with analytical results, which confirms the accuracy of the method.
124(2008); http://dx.doi.org/10.1121/1.2963187View Description Hide Description
A major problem in moving platform active sonar systems is the detection of targets in spatially distributed and Doppler-spread reverberation. This paper presents a novel space time adaptive prewhitener for reverberation based on a two-dimensional autoregressive model. The space time adaptive prewhitener jointly processes received data in angle and Doppler to improve the separation of a target from reverberation. The detector using the space time adaptive prewhitener is shown to yield better detection performance than previously known schemes when operating in a reverberation background containing target echoes.
124(2008); http://dx.doi.org/10.1121/1.2960899View Description Hide Description
Most fish cannot hear frequencies above , but a few species belonging to the subfamily Alosinae (family Clupeidae) can detect intense ultrasound. The response of adult specimens of the European allis shad (Alosa alosa) to sinusoidal ultrasonic pulses at 70 and is tested. The fish showed an intensity-graded response to the ultrasonic pulses with a response threshold between 161 and re (pp) for both frequencies. These response thresholds are similar to thresholds derived from juvenile American shad (Alosa sapidissima) in previous studies, supporting the suggestion that these members of Alosinae have evolved a dedicated ultrasound detector adapted to detect and respond to approaching echolocating toothed whales.
124(2008); http://dx.doi.org/10.1121/1.2960935View Description Hide Description
This letter deals with precision issues in the determination of the timing of the room impulse responses (RIRs) onset. First, it is shown that while errors of onset timing estimation do not have that much effect on temporal indices, an erroneous onset estimation leads to significant differences in energetic and statistic acoustical indices. Twelve automatic onset detection methods are compared, in terms of precision, robustness, and complexity. Experimental validation made on a set of 100 RIRs provides good evidence in favor of spectral and/or energetic methods, according to the type of sound source.
124(2008); http://dx.doi.org/10.1121/1.2960936View Description Hide Description
The biorobotic emulation of swimming and flying animals carrying out short-distance echolocation while maneuvering is considered. A simple and lightweight sonar for use on a small, maneuverable underwater vehicle for short-distance echolocation is explored. This sonar has four sensors and uses broadband, high-frequency signals to echolocate. The frequency-time characteristics of these signals are compared to those of bats and dolphins. The biosonar is paired with a biologically inspired, maneuverable, underwater vehicle, the combined use of sensors and maneuverability being analogous to animal behavior. Homing experiments have been carried out in an acoustic test facility where identification and localization of multiple targets is based on fusion of acoustic returns from multiple pings.
124(2008); http://dx.doi.org/10.1121/1.2968299View Description Hide Description
The goal of this work is to investigate experimentally the music intervals in modern Byzantine Chant performance and to compare the obtained results with the equal temperament scales introduced by the Patriarchal Music Committee (PMC). Current measurements resulted from pressure and electroglottographic recordings of 13 famous chanters singing scales of all the music genera. The scales’ microintervals were derived after pitch detection based on autocorrelation, cepstrum, and harmonic product spectrum analysis. The microintervallic differences between the experimental values and the PMC’s ones were statistically analyzed indicating large deviation of the mean values and the standard deviations. Significant interaction effects were identified among some genera and between ascending and descending scale directions.
- BOOK REVIEWS
- REVIEWS OF ACOUSTICAL PATENTS
124(2008); http://dx.doi.org/10.1121/1.2968241View Description Hide Description
The purpose of these acoustical patent reviews is to provide enough information for a Journal reader to decide whether to seek more information from the patent itself. Any opinions expressed here are those of the reviewers as individuals and are not legal opinions. Printed copies of United States Patents may be ordered at $3.00 each from the Commissioner of Patents and Trademarks, Washington, DC 20231. Patents are available via the Internet at http://www.uspto.gov.
- LETTERS TO THE EDITOR
124(2008); http://dx.doi.org/10.1121/1.2968685View Description Hide Description
Detection threshold for a pure tone signal centered in a narrow band of noise may be reduced by inclusion of additional flanking masker bands, provided that they share coherent amplitude modulation (AM) across frequency. This comodulation masking release (CMR) associated with coherent AM across frequency is often much smaller if the signal and on-signal masker are presented to one ear and the flanking masker band(s) are presented contralaterally. An experiment was carried out to explore the role of peripheral effects (e.g., suppression) and central effects (e.g., grouping) in this finding. As frequently reported, CMR was smaller when two or more flanking maskers were presented contralaterally to the signal than when presented ipsilaterally. An intermediate condition, where a subset of flanking maskers was presented to each ear, provided comparable benefit to presenting all flankers ipsilateral to the signal. This result suggests that central effects may play a significant role in the reduced dichotic CMR under some conditions.
- GENERAL LINEAR ACOUSTICS 
On the transient solutions of three acoustic wave equations: van Wijngaarden’s equation, Stokes’ equation and the time-dependent diffusion equation124(2008); http://dx.doi.org/10.1121/1.2973231View Description Hide Description
Acoustic wave propagation in a dispersive medium may be described by a wave equation containing one or more dissipation terms. Three such equations are examined in this article: van Wijngaarden’s equation (VWE) for sound propagating through a bubbly liquid; Stokes’ equation for acoustic waves in a viscous fluid; and the time-dependent diffusion equation (TDDE) for waves in the interstitial gas in a porous solid. The impulse-response solution for each of the three equations is developed and all are shown to be strictly causal, with no arrivals prior to the activation of the source. However, the VWE is nonphysical in that it predicts instantaneous arrivals, which are associated with infinitely fast, propagating Fourier components in the Green’s function. Stokes’ equation and the TDDE are well behaved in that they do not predict instantaneous arrivals. Two of the equations, the VWE and Stokes’ equation, satisfy the Kramers-Kronig dispersion relations, while the third, the TDDE, does not satisfy Kramers-Kronig, even though its impulse-response solution is causal and physically realizable. The Kramers-Kronig relations are predicated upon the (mathematical) existence of the complex compressibility, a condition which is not satisfied by the TDDE because the Fourier transform of the complex compressibility is not square-integrable.