Volume 115, Issue 4, April 2004
- acoustical news—usa
- acoustical news—international
- advanced-degree dissertation abstracts
- book reviews
- reviews of acoustical patents
- letters to the editor
- general linear acoustics 
- nonlinear acoustics 
- underwater sound 
- ultrasonics, quantum acoustics, and physical effects of sound 
- structural acoustics and vibration 
- noise: its effects and control 
- architectural acoustics 
- acoustic signal processing 
- psychological acoustics 
- speech production 
- speech perception 
- bioacoustics 
Index of content:
- ADVANCED-DEGREE DISSERTATION ABSTRACTS
115(2004); http://dx.doi.org/10.1121/1.1648679View Description Hide Description
The purpose of the reported study is to discover an effective method of characterizing movement patterns of the crucial articulator as the function of an abstract syllable magnitude and the adjacent boundary, and at the same time to investigate effects of prosodic control on utterance organization. In particular, the speed of movement when a flesh point on the tongue blade or the lower lip crosses a selected position relative to the occlusion plane is examined. The time of such crossing provides an effective measure of syllable timing and syllable duration according to previous work. In the present work, using a very limited vocabulary with only a few consonants and one vowel as the key speech materials, effects of contrastive emphasis on demisyllabic movement patterns were studied. The theoretical framework for this analysis is the C/D model of speech production in relation to the concept of an invariant part of selected articulatory movements. The results show evidence in favor of the existence of “iceberg” patterns, but a linear dependence of slope on the total excursion of the demisyllabic movement, instead of the approximate constancy of the threshold crossing speed as suggested in the original proposal of the iceberg, has been found. Accordingly, a revision of the original concept of iceberg, seems necessary. This refinement is consistent with the C/D model assumption on “prominence control” that the syllable magnitude determines the movement amplitude, accompanying directly related syllable duration change. In this assumption, the movement of a consonantal component should also be proportional to syllable magnitude. The results suggests, however, systematic outliers deviating from the linear dependence of movement speed on excursion. This deviation may be caused by the effect of the immediately following boundary, often referred to as phrase-final elongation.
Thesis advisor: Osamu Fujimura
Copies of this thesis written in English can be obtained from
Computation of exhaust mixing noise using large-eddy simulation turbulence modeling and Lighthill's acoustic analogy115(2004); http://dx.doi.org/10.1121/1.1689339View Description Hide Description
This research involves computational study of free, heated jet flow and resultant far-field sound performed using large-eddy simulation(LES) and Lighthill's acoustic analogy. A subgrid-scale model for small-scale compressible turbulence was developed using a combination of the popular Smagorinsky model and a deductive model. An existing software package for compressible flow field computation was substantially modified to perform temporal LES and aerosound simulations. Cases studied extend to large Reynolds number (Re), high subsonic (compressible) flow with realistic geometries more representative of aircraft engine exhausts than typically considered using direct numerical simulation (DNS). Flow-field fluctuations are stored over a period of time and used to calculate rms turbulence within the computational domain. The far-field sound and directivity is computed using the time-derivative form of Lighthill's source-integral result formulated in terms of quadrupole sources from the simulated flow field, which is integrated in time and contains the fluctuations set up by the time-varying stress tensor. A simulation for a WR19–4 turbofan engine exhaust (Re>106 based on exist velocity and diameter) is presented, and propagated jet noise results are compared with experimental acoustic data.
Thesis advisor: William C. Meecham
Copies of this thesis written in English can be obtained from
An analytic model for acoustic scattering from an impedance cylinder placed normal to an impedance plane115(2004); http://dx.doi.org/10.1121/1.1738214View Description Hide Description
An analytic model, developed in cylindrical coordinates, is described for the scattering of a spherical wave off a semi-infinite reight cylinder placed normal to a ground surface. The motivation for the research is to have a model with which one can simulate scattering from a single tree and which can be used as a fundamental element in a model for estimating the attenuation in a forest comprised of multiple tree trunks. Comparisons are made to the plane wave case, the transparent cylinder case, and the rigid and soft ground cases as a method of theoretically verifying the model for the contemplated range of model parameters. Agreement is regarded as excellent for these benchmark cases. Model sensitivity to five parameters is also explored. An experiment was performed to study the scattering from a cylinder normal to a ground surface. The data from the experiment is analyzed with a transfer function method to yield frequency and impulse responses, and calculations based on the analytic model are compared to the experimental data.
Thesis advisor: David C. Swanson
Copies of this thesis written in English can be obtained from
- BOOK REVIEWS
115(2004); http://dx.doi.org/10.1121/1.1687422View Description Hide Description
- REVIEWS OF ACOUSTICAL PATENTS
115(2004); http://dx.doi.org/10.1121/1.1689349View 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
115(2004); http://dx.doi.org/10.1121/1.1649332View Description Hide Description
A new expression of the backscattering form function for cylindrical targets, suspended in an inviscid fluid in a plane incident sound field, is presented. The theory is modified to include the effects of absorption of shear and compressional waves in viscoelastic materials. The numerical results presented show how damping effect due to ultrasound absorption influences the cylinder’s material properties.
Discussions on “Radial vibrations of orthotropic laminated hollow spheres” [J. Acoust. Soc. Am. 113, 847–851 (2003)] (L)115(2004); http://dx.doi.org/10.1121/1.1649911View Description Hide Description
With the assumption of radial vibration, there exists only a trivial solution for a general orthotropic hollow sphere and the nonzero solution can be obtained only for a spherically isotropic hollow sphere (a special case of the orthotropic hollow sphere) and the corresponding proofs are presented. So, the numerical results given by Stavsky and Greenberg [J. Acoust. Soc. Am. 113, 847–851 (2003)] for a general orthotropic hollow sphere are unreasonable.
115(2004); http://dx.doi.org/10.1121/1.1652035View Description Hide Description
The dynamic stability of an elastically supported Timoshenko beam exited by a continuous sequence of identical, mass particles attached to and traveling at a constant velocity across the beam has been investigated. The regions of dynamic stability are determined for different physical system parameters. Floquet theory is utilized to study the parametric regions of stability, which are displayed in graphical form.
115(2004); http://dx.doi.org/10.1121/1.1649931View Description Hide Description
For listeners with cochlear hearing loss, cochlear damage may include “dead regions” with no functioning inner hair cells and/or associated neurons. Recent studies indicate that amplifying frequencies more than 1.7 times the edge frequency of a high-frequency dead region is unlikely to improve (and may reduce) speech scores [Vickers et al., J. Acoust. Soc. Am. 110, 1164–1175 (2001); Baer et al., J. Acoust. Soc. Am. 112, 1133–1144 (2002)]. These results were taken as evidence that tests to identify dead regions could improve hearing aid fitting. In the current study, practicing audiologists examined audiograms of listeners diagnosed as having high-frequency dead regions. The audiologists were given no specific information regarding dead regions for any individual, and were asked to base amplification decisions entirely on the audiograms. Most audiologists did not recommend amplification of frequencies with hearing losses exceeding 90 dB HL. Reexamination of speech results reported by Vickers et al. and Baer et al. indicated that limiting amplification based on audiograms alone (90-dB rule) or on specific testing for dead regions rule) produced similar performance. Thus, testing for dead regions may not provide important information for hearing aid fitting that is not already available in the audiogram.
- GENERAL LINEAR ACOUSTICS 
Fractional Laplacian time-space models for linear and nonlinear lossy media exhibiting arbitrary frequency power-law dependency115(2004); http://dx.doi.org/10.1121/1.1646399View Description Hide Description
Frequency-dependent attenuation typically obeys an empirical power law with an exponent ranging from 0 to 2. The standard time-domain partial differential equationmodels can describe merely two extreme cases of frequency-independent and frequency-squared dependent attenuations. The otherwise nonzero and nonsquare frequency dependency occurring in many cases of practical interest is thus often called the anomalous attenuation. In this study, a linear integro-differential equationwavemodel was developed for the anomalous attenuation by using the space-fractional Laplacian operation, and the strategy is then extended to the nonlinear Burgers equation. A new definition of the fractional Laplacian is also introduced which naturally includes the boundary conditions and has inherent regularization to ease the hypersingularity in the conventional fractional Laplacian. Under the Szabo’s smallness approximation, where attenuation is assumed to be much smaller than the wave number, the linear model is found consistent with arbitrary frequency power-law dependency.
115(2004); http://dx.doi.org/10.1121/1.1675817View Description Hide Description
Our purpose in this paper is to describe the wave propagation in media whose attenuation obeys a frequency power law. To achieve this, a frequency–domain wave equation was developed using previously derived causal dispersion relations. An inverse space and time Fourier transform of the solution to this algebraic equation results in a time–domain solution. It is shown that this solution satisfies the convolutional time–domain wave equation proposed by Szabo [J. Acoust. Soc. Am. 96, 491–500 (1994)]. The form of the convolutional loss operator contained in this wave equation is obtained. Solutions representing the propagation of both plane sinusoidal and transient waves propagating in media with specific power law attenuation coefficients are investigated as special cases of our solution. Using our solution, comparisons are made for transient one-dimensional propagation in a medium whose attenuation is proportional to frequency with recently obtained numerical solutions of Szabo’s equation. These show good agreement.
115(2004); http://dx.doi.org/10.1121/1.1646137View Description Hide Description
A modal model is developed for the propagation of sound over an impedance ground plane in a stratified atmosphere which is downward refracting near the ground but upward refracting at high altitudes. The sound’s interaction with the ground is modeled by an impedance with both real and imaginary parts so that the ground is lossy as well as compliant. Such sound speed profiles are typical of the atmospheric boundary layer at night and, together with the ground impedance, have been used extensively to model ground to ground sound propagation in the nocturnal environment. Applications range from community noise and bioacoustics to meteorology. The downward refraction near the ground causes the propagation to be ducted, suggesting that the long range propagation is modal in nature. This duct is, however, leaky due to the upward refraction at high altitudes. The modal model presented here accounts for both the attenuation of sound by the ground as well as the leaky nature of the duct.
Caustic envelopes and cusp coordinates due to the reflection of a spherical wave from a layered sediment115(2004); http://dx.doi.org/10.1121/1.1650841View Description Hide Description
A compilation of analytical formulas is presented, describing ray properties of a family of sediment sound speed profiles. The profiles are described as “generalized power law” profiles because they are generalizations of a similar family of simpler power law profiles considered in earlier work [M. A. Ainslie, J. Acoust. Soc. Am. 96, 2506–2515 (1994)]. Properties considered include ray paths, caustic envelopes, and cusp coordinates due to a point source in isovelocity water. For a few example cases the caustic shapes are illustrated by computing the pressure field using a normal mode program.
115(2004); http://dx.doi.org/10.1121/1.1689345View Description Hide Description
Clusters of N thin parallel and identical shells (aligned or not) in water are considered. Assuming a harmonic plane wave is normally incident upon one cluster, the scattered-field classical expression is recalled, and then computed for different types of clusters, along with resonance spectra. The scattering S matrix is defined, and its unitarity property used to check the numerical results. All spectra are compared with that of a single shell, in the frequency range where resonances are due to an A-wave phase matching only. Whatever the cluster, each resonance of the single shell is seen to split into M different ones. The value of M depends on the number of shells, the distance between them, and the symmetries of the cluster. Apart from the very special case of aligned shells no simple law has been found to predict the value of M.
115(2004); http://dx.doi.org/10.1121/1.1652036View Description Hide Description
The acoustic center of a reciprocal transducer is defined as the point from which spherical waves seem to be diverging when the transducer is acting as a source. This paper examines various ways of determining the acoustic center of a source, including methods based on deviations from the inverse distance law and methods based on the phase response. The considerations are illustrated by experimental results for condensermicrophones.
Computing fluid-coupled resonance frequencies, mode shapes, and damping loss factors using the singular value decomposition115(2004); http://dx.doi.org/10.1121/1.1652034View Description Hide Description
In many acoustic design problems, it would be useful to be able to compute fluid-coupled resonance frequencies, mode shapes, and their associated damping levels. Unfortunately, conventional eigenvalue solution procedures are either computationally inefficient, unreliable, or have limited applicability. Sophisticated methods for identifying modal parameters using the singular value decomposition have recently emerged in the area of experimental modal analysis, where the available data typically consists of velocity-to-force transfer functions for several drive point locations. In this paper, we show that these techniques can be applied to numerically generated frequency domain data and are even more effective because full matrices of transfer function data are available. This typically allows the modes to be completely separated from each other, such that the modal parameters can be identified using analytical formulas. Several benchmark example problems are solved numerically, including a rectangular cantilever plate, a baffled circular plate, and a baffled circular plate covered by an open-ended rigid-walled pipe.