Volume 120, Issue 3, September 2006
- jasa express letters
- acoustical news—usa
- acoustical standards news
- book reviews
- reviews of acoustical patents
- letters to the editor
- general linear acoustics 
- nonlinear acoustics 
- aeroacoustics, atmospheric sound 
- underwater sound 
- transduction 
- structural acoustics and vibration 
- architectural acoustics 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech production 
- speech perception 
- speech processing and communication systems 
- bioacoustics 
Index of content:
- JASA EXPRESS LETTERS
120(2006); http://dx.doi.org/10.1121/1.2234517View Description Hide Description
A computationally efficient method for discriminating between near- and far-field infrasound sources using array time-difference of arrival (TDOA) information is described. Rather than assess wave-front curvature, the discriminant quantifies the statistical departure of TDOA information from that of a plane wave passing the array. Since the method constrains neither the functional form nor the amplitude characteristics of a signal it is suited for discrimination of signals across large-aperture infrasound arrays. Experimental results confirm theoretical predictions to a range of order ten array apertures. The discriminant is applied to data from an Antarctic infrasound array.
120(2006); http://dx.doi.org/10.1121/1.2234518View Description Hide Description
Blast wave propagation measurements were conducted to investigate nonlinear propagation effects on blast waveform evolution with distance. Measurements were made with a wide-bandwidth capacitormicrophone for comparison with conventional 3.175-mm (1/8-in.) microphones with and without baffles. It was found that the 3.175-mm microphone did not have sufficient high-frequency response to capture the actual rise times in some regions. For a source of of C-4 plastic explosive, the trend observed is that nonlinear effects steepened the waveform, thereby decreasing the shock rise time, up to a range of . At , the rise times had increased slightly.
120(2006); http://dx.doi.org/10.1121/1.2234519View Description Hide Description
Previous investigations have shown that one mechanism of irregular vocal fold vibration may be a desynchronization of two or more vibratory modes of the vocal fold tissues. In the current investigation, mechanisms of irregular vibration were further examined using a self-oscillating, physical model of vocal fold vibration, a hemi-model methodology, and high-speed, stereoscopic, digital imaging. Using the method of empirical eigenfunctions, a spatiotemporal analysis revealed mechanisms of irregular vibration in subharmonic phonation and biphonation, which were not disclosed in a standard acoustic spectrum.
120(2006); http://dx.doi.org/10.1121/1.2266023View Description Hide Description
Using vector acoustic sensors for marine geoacoustic surveys instead of the usual scalar hydrophones enables one to acquire three-dimensional (3D) survey data with instrumentation and logistics similar to current 2D surveys. Vector acoustic sensorsmeasure the sound wave direction directly without the cumbersome arrays that hydrophones require. This concept was tested by a scaled experiment in an acoustic water tank that had a well-controlled environment with a few targets. Using vector acoustic data from a single line of sources, the three-dimensional tank environment was imaged by directly locating the source and all reflectors.
- BOOK REVIEWS
- REVIEWS OF ACOUSTICAL PATENTS
120(2006); http://dx.doi.org/10.1121/1.2355929View 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
120(2006); http://dx.doi.org/10.1121/1.2221536View Description Hide Description
The traditional Pekeris treatment of the shallow water acoustic waveguide is marred by a seeming paradox: The so-called nonorthogonality of the propagation modes. This anomaly is due to the use of mistaken orthogonality criteria, and is easily exorcised by the use of normal coordinate theory (which leads to the correct orthonormality conditions for any linear conservative system).
120(2006); http://dx.doi.org/10.1121/1.2216767View Description Hide Description
The prediction of sound propagation past a curved, rigid, rough surface can be improved by utilizing a modified surface admittance that is calculated by replacing the standard roughness parameter, , with a complex roughness parameter. The inclusion of a complex roughness, , accounts for the attenuation of the boundary wave with distance by incoherent scattering. This analogy has been successfully used to predict the sound field behind a rough, curved, rigid surface at several frequencies, by computing the creeping wave series with a best-fit surface parameter, .
120(2006); http://dx.doi.org/10.1121/1.2221559View Description Hide Description
Previous work on adjoint modeling of underwater acoustic propagation for the purposes of environmental inversions developed the necessary numerical algorithms based on a finite difference implementation of the parabolic equation. In this letter, the corresponding formulation for the split-step Fourier implementation is presented. Although no calculations have yet been made with this approach, the method is completely consistent with previous work, and the final form of the tangent linear model is exactly the same. However, the formulation of the operators in the split-step Fourier approach provides a simple means of estimating both local and global effects on uncertainty. This letter is then provided for anyone who may wish to attempt adjoint modeling with a split-step Fourier model.
Reply to comment on “Auditory-nerve first-spike latency and auditory absolute threshold: A computer model”120(2006); http://dx.doi.org/10.1121/1.2221413View Description Hide Description
Krisha [J. Acoust. Soc. Am., in press (2006)] has commented that an explanation based on presynaptic calcium accumulation at the inner hair cell is an incorrect explanation for the success of a model of the auditory periphery [Meddis, R., J. Acoustic. Soc. Am.119, 406–417 (2006)] in explaining data on first-spike auditory nerve latency. This reply accepts the criticism and accepts the strength of an alternative explanation based on expected latencies in random sequences of low-probability events. This reply also goes on briefly to explore the application of this argument to other phenomena, including the dependence of absolute auditory threshold on the duration of the stimulus. This has wide-ranging implications for the concept of “temporal integration” in psychophysics.
- GENERAL LINEAR ACOUSTICS 
120(2006); http://dx.doi.org/10.1121/1.2227372View Description Hide Description
This paper is concerned with the basic equations governing energy and intensity in incoherent ray fields. Some fictitious sources are distributed on the boundary of the domain but also on diffracting wedges and peaks. Their powers are determined by some appropriate boundary integral equations. Once these powers are known, energy and intensity inside the domain are given by a simple superposition of contributions of these sources. All paths of propagation are taken into account including direct, reflected, refracted, transmitted, and diffracted rays, but also, radiation by surface, edge or corner modes, and the reciprocal paths for structural response. This theory unifies several fields from the “radiosity method” in room acoustics which determines the reverberation time to the “radiative transfer method” in structural dynamics which gives the repartition of vibrational energy inside subsystems of built-up structures. This is therefore a candidate for an alternative to statistical energy analysis when fields are nondiffuse.
120(2006); http://dx.doi.org/10.1121/1.2225997View Description Hide Description
A set of coupled integral equations is formulated for the investigation of sound propagation from an infinitesimal harmonic line source above a hard ground surface corrugated with cuttings. Two half-space Green’s functions are employed in the formulation. The first one defined for the upper half space is used to reduce the problem size and eliminate the edge effect resulting from the boundary truncation; the other one for the lower half space is to simplify the representation of the Neumann-Dirichlet map. As a result, the unknowns are only distributed over the corrugated part of the surface, which leads to substantial reduction in the size of the final linear system. The computational complexity of the Neumann-Dirichlet map is also reduced. The method is used to analyze the behavior of sound propagation above textured surfaces the impedance of which is expectedly altered. The effects of number and opening of trench cuttings, and the effect of source height are investigated. The conclusions drawn can be used for reference in a practical problem of mitigating gun blast noise.
An experimental investigation of guided wave propagation in corrugated plates showing stop bands and pass bands120(2006); http://dx.doi.org/10.1121/1.2221534View Description Hide Description
Nonplanar surfaces are often encountered in engineering structures. In aerospace structures, periodically corrugated boundaries are formed by friction-stir-welding. In civil engineering structures, rebars used in reinforced concrete beams and slabs have periodic surface. Periodic structures are also being used to create desired acoustic band gaps. For health monitoring of these structures, a good understanding of the elastic wave propagation through such periodic structures is necessary. Although a number of research papers on the wave propagation in periodic structures are available in the literature, no one experimentally investigated the guided wave propagation through plates with periodic boundaries and compared the experimental results with theoretical predictions as done in this paper. The experimental results clearly show that elastic waves can propagate through the corrugated plate (waveguide) for certain frequencies called “pass bands,” and find it difficult to propagate for some other frequencies called “stop bands.” Stop bands are found to increase with the degree of corrugation. Experimental results are compared with the theoretical predictions, and good matching is observed for plates with small degree of corrugation. Only two parameters—the depth of corrugation and the wavelength of the periodicity—are sufficient for modeling the elastic wave propagation in slightly corrugated plates.
Optimization of multilayered panels with poroelastic components for an acoustical transmission objective120(2006); http://dx.doi.org/10.1121/1.2228663View Description Hide Description
A method for optimizing acoustical linings is described and applied to multilayered panels including solid, fluid, and porous components. This optimization is based on an analytical simulation of the insulation properties and a genetic algorithm. The objective function is defined by taking into account both the acoustical frequency response over a 1/3 octave spectrum and the total mass of the panel. The optimization process gives rise to an optimal choice for the number of layers as well as for the nature and the thickness of each layer that maximizes the transmission loss. A practical example of such an optimization is described.
120(2006); http://dx.doi.org/10.1121/1.2221407View Description Hide Description
This paper deals with a new method for solving coupled acoustical problems such as those arising from the study of insulation panels with porous linings. The main idea is to use the boundary element method (BEM) for modeling porous media in order to simplify problem solving in mid-frequency range. This approach reduces the entire problem to only unknowns on the boundaries. Developments have been oriented in a bi-dimensional formulation with a constant element discretization scheme. A multi-region assembly of porous subdomains and a coupling procedure with structural finite elements complete this approach. Comparisons between the finite element method (FEM) and the present solution (mixed FEM and BEM) show a close agreement. Moreover, the analysis of a multi-layer system through this mixed numerical method results in faster processing time and less memory usage than a conventional full finite element method.
120(2006); http://dx.doi.org/10.1121/1.2221410View Description Hide Description
A method is derived for the fast, exact prediction of acoustic fields around rotating sources by using a series expansion which generalizes a previously published method for a circular piston. The technique gives exact predictions for the field outside the sphere containing the rotor in a computational time two orders of magnitude less than that required for direct numerical evaluation of the acoustic integrals. Its use is demonstrated by application to two sample problems characteristic of real aircraft propellers.