Volume 108, Issue 5, November 2000
- acoustical news—usa
- book reviews
- reviews of acoustical patents
- general linear acoustics 
- nonlinear acoustics 
- aeroacoustics, atmospheric sound 
- underwater sound 
- ultrasonics, quantum acoustics, and physical effects of sound 
- transduction 
- structural acoustics and vibration 
- architectural acoustics 
- acoustical measurements and instrumentation 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech perception 
- music and musical instruments 
- bioacoustics 
- letters to the editor
- program abstracts of the 140th meeting of the acoustical society of america
Index of content:
- REVIEWS OF ACOUSTICAL PATENTS
108(2000); http://dx.doi.org/10.1121/1.1318778View 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.
- GENERAL LINEAR ACOUSTICS 
108(2000); http://dx.doi.org/10.1121/1.1315289View Description Hide Description
This article considers the propagation of elastic waves in an eight-ply quasi-isotropic laminate arising from line sources of dislocation located at each of the seven interfaces in turn. The laminate is composed of identical layers of a fiber composite material which is modeled as a homogeneous transversely isotropic elastic continuum with the axis of transverse isotropy along the fiber direction. The line source sets up a straight crested wave traveling along the laminate in the direction normal to the load line and the elastodynamic equations within each layer are solved by taking the Laplace transform with respect to time and the Fourier transform with respect to the spatial coordinate in the direction of propagation. The resulting system of six first-order differential equations in each layer is solved to obtain the transforms of the displacement and stress components throughout the laminate. The time history of any displacement or stress component at any location may then be recovered by numerical inversion of the double transform. The graphs presented show the time history of the normal displacement of the top surface of the laminate at distances of 1 and 20 plate thicknesses from the plane of action of the sources. These graphs are for four different orientations of the line of action of the sources, namely, at angles 0, 30, 60, and 90 degrees to the fiber direction in the surface layer. The numerical inversion involves a summation over different modes of Rayleigh–Lamb waves in the laminate and results are also presented showing the contributions to the overall response from some of the individual modes.
108(2000); http://dx.doi.org/10.1121/1.1314317View Description Hide Description
The effect of water vapor on the shear and compressional wave speeds in two different kinds of glass beads and in Ottawa sand has been measured. The nominal diameter of the glass beads was 125 μm and of the sand, 500 μm. Measurements were made as the water vapor was introduced slowly into the evacuated material. The vapor pressure isotherm for the beads made of glass with a high concentration of titanium and barium oxides was fit reasonably well by the simple Brunauer–Emmett–Teller (BET) theory. For the Ottawa sand, the BET theory fit the vapor pressure isotherm if the surface area of the grains was assumed to be three times the area calculated, assuming all of the grains were spheres with a diameter of 500 μm. In these two materials, the vapor had little effect on the wave speeds. For beads made of glass containing sodium oxide, however, the wave speeds approximately double with the introduction of water vapor, and the vapor pressure isotherm had the BET shape only if the saturated vapor pressure was assumed to be lowered by 20%. These results have been explained by assuming that a chemical reaction occurred between the lime glass and the water to form a gel.
108(2000); http://dx.doi.org/10.1121/1.1314316View Description Hide Description
In this paper, dispersion of guided waves in a three-layered sandwich plate is considered. The focus here is on a configuration consisting of a thin anisotropic layer sandwiched between two identical isotropic layers. This configuration could model, for example, a superconducting tape where the middle layer is a brittle superconductor and the surrounding layers are isotropic and ductile. An approximate dispersion relation correct to governing the guided waves is obtained by expanding the field inside the thin middle layer in powers of the small thickness h of the layer. Numerical examples are given for two specific systems with superconducting middle layers. Some characteristic features, particularly at low frequencies, are investigated. Comparison between the exact and approximate dispersion relations are made to show that the approximation works well in the frequency interval of interest. The characteristic features may be useful for ultrasonic measurements of the anisotropicelastic constants of the thin layer.
- NONLINEAR ACOUSTICS 
108(2000); http://dx.doi.org/10.1121/1.1312360View Description Hide Description
In this paper, a new tool is proposed to carry out acoustic cavitation monitoring and to have an overview of its effects in applications. After a brief review of the cavitation characterization techniques, it is shown that cavitationnoise is a suitable and accurate indicator of the cavitation activity induced in a liquid. In the first part of this study, the origin of the first spectral component of the cavitationnoise is discussed. The and component evolution measurement at a driving frequency around 1 MHz confirms Neppiras’ ones and gives an indicator of the cavitation inception. In the second part, the cavitationnoise spectrum distortion is considered as a function of the acoustic power transmitted to the liquid in order to obtain an indicator of cavitation activity. In the last part, this new tool is used to bring to the fore the hysteresis effect associated with the cavitation. An experimental correlation between cavitationnoise power measurement and the sonochemical activity in an oxidization process is also presented.
- AEROACOUSTICS, ATMOSPHERIC SOUND 
A turbulence spectral model for sound propagation in the atmosphere that incorporates shear and buoyancy forcings108(2000); http://dx.doi.org/10.1121/1.1311779View Description Hide Description
A three-dimensional model for turbulentvelocityfluctuations in the atmospheric boundary layer is developed and used to calculate scattering of sound. The model, which is based on von Kármán’s spectrum, incorporates separate contributions from shear- and buoyancy-forced turbulence. New equations are derived from the model that predict the strength and diffraction parameters for scattering of sound as a function of height from the ground and atmospheric conditions. The need is demonstrated for retaining two distinct scattering length scales, one associated with scattering strength and the other with diffraction. These length scales are height dependent and vary substantially with the relative proportions of shear and buoyancy forcing. The turbulencemodel predicts that for forward-scattered waves the phase variance is much larger than the log-amplitude variance, a behavior borne out by experimental data. A new method for synthesizing random fields, based on empirical orthogonal functions, is developed to accommodate the height dependence of the turbulencemodel. The method is applied to numerical calculations of scattering into an acoustic shadow zone, yielding good agreement with previous measurements.
- UNDERWATER SOUND 
108(2000); http://dx.doi.org/10.1121/1.1288666View Description Hide Description
The proper evaluation of sound propagation between sources/receivers and scatterers is important in characterizing bottom volume scattering. In this article, several sound propagationmodels used in bottom volume scattering studies are evaluated and their results compared to the exact solution obtained through a numerical wave number integration technique. It is found that Hines’ approach [J. Acoust. Soc. Am. 88, 324–334 (1990)] works well for the two isovelocity half-space case except when the grazing angle is close to the critical angle. The far-field approximation, given by Ivakin [Sov. Phys. Acoust. 32(6), 492–496 (1986)] and Mourad and Jackson [J. Acoust. Soc. Am. 94, 344–358 (1993)], has a performance depending upon the sound speed structure in the sediment. For an isovelocity slow bottom, it agrees well with the exact solution. However, discrepancies arise for an isovelocity fast bottom or a bottom with a complex sound speed structure. In addition, the appropriateness of using the equivalent surface scattering strength as a function of grazing angle in volume scattering characterizations is studied. In conclusion, precautions need to be taken in modeling both the propagation effects and the scattering mechanisms associated with the bottom volume scattering process.
108(2000); http://dx.doi.org/10.1121/1.1308047View Description Hide Description
The bistatic scattering characteristics of two geologically distinct abyssal hills located on the western flank of the Mid-Atlantic Ridge, known as and are experimentally compared using data acquired with low-frequency towed-array systems at convergence zone (∼33 km) stand-off. The comparison is significant because the abyssal hills span the two classes of elevated seafloor crust that cover the Mid-Atlantic Ridge. The highly lineated feature is representative of abyssal hills composed of outside corner crust, the most commonly occurring category, whereas the domed promontory is representative of the rougher, low-aspect-ratio abyssal hills composed of inside corner crust. The latter are less common and usually restricted to segment valley margins. The mean biazimuthal scattering distributions of the two abyssal hills each exhibit Lambertian behavior with comparable albedos, suggesting that the distinction between abyssal hills composed of differing crust is not significant in modeling long-range reverberation. The adverse effect of using bathymetry that undersamples seafloor projected area in scattering strength analysis is also quantified with data from the ridge. Specifically, the use of undersampled bathymetry can lead to significant overestimates in the strength of seafloor scattering.
108(2000); http://dx.doi.org/10.1121/1.1289371View Description Hide Description
The Helmholtz–Kirchhoff integral and the Kirchhoff approximation are applied to model the penetration of sound waves into rough sandy seafloors at grazing angles above and below the critical angle. As the seafloor of interest is anisotropic, emphasis is placed on simulating the response from a two-dimensional interface. The analytical development of the method is first presented, followed by numerical examples. Simulations and data acquired at sea are in very good agreement in the 2–15 kHz band [Maguer et al., J. Acoust. Soc. Am. 107, 1215–1225 (2000)]. The model predicts, in agreement with the 2–15 kHz acoustic data, the contributions due to roughness effects that dominate the evanescent wave component over most of this frequency band. Secondary effects such as coherent (Bragg) influence patterns and the loss of signal coherence with grazing angle or depth are correctly predicted. The model simulations strongly suggest that roughness of the sediment interface is most likely the cause of anomalous sound penetration into the seabed.
108(2000); http://dx.doi.org/10.1121/1.1289669View Description Hide Description
In this paper, impulse response matching is proposed for source localization and environmental inversion. The ocean impulse response is estimated using a cross-correlation procedure applied to data from the propagation of a broadband pulse in a shallow-water environment. Source localization and geoacoustic parameter estimation are then performed through time-domain correlations between the estimated impulse responses at spatially separated phones and synthetic replica impulse responses. The method is both spatially and temporally coherent. Parameter space search uses a hierarchical scheme designed to exploit the sensitivity of the acoustic field to the unknown parameters. Tested on the SWellEX-96 and synthetic data, the proposed method is shown to be more robust than conventional (linear), incoherent, broadband matched field processing.
- ULTRASONICS, QUANTUM ACOUSTICS, AND PHYSICAL EFFECTS OF SOUND 
Kramers–Kronig relations applied to finite bandwidth data from suspensions of encapsulated microbubbles108(2000); http://dx.doi.org/10.1121/1.1312364View Description Hide Description
In this work, the Kramers–Kronig (K–K) relations are applied to experimental data of resonant nature by limiting the interval of integration to the measurement spectrum. The data are from suspensions of encapsulated microbubbles (Albunex®) and have the characteristics of an ultrasonicnotch filter. The goal is to test the consistency of this dispersion and attenuation data with the Kramers–Kronig relations in a strict manner, without any parameters from outside the experimental bandwidth entering in to the calculations. In the course of reaching the goal, the artifacts associated with the truncation of the integrals are identified and it is shown how their impacts on the results can be minimized. The problem is first approached analytically by performing the Kramers–Kronig calculations over a restricted spectral band on a specific Hilbert transform pair (Lorentzian curves). The resulting closed-form solutions illustrate the type of artifacts that can occur due to truncation and also show that accurate results can be achieved. Next, both twice-subtracted and lower-order Kramers–Kronig relations are applied directly to the attenuation and dispersion data from the encapsulated microbubbles. Only parameters from within the experimental attenuation coefficient and phase velocitydata sets are used. The twice-subtracted K–K relations produced accurate estimates for both the attenuation coefficient and dispersion across all 12 data sets. Lower-order Kramers–Kronig relations also produced good results over the finite spectrum for most of the data. In 2 of the 12 cases, the twice-subtracted relations tracked the data markedly better than the lower-order predictions. These calculations demonstrate that truncation artifacts do not overwhelm the causal link between the phase velocity and the attenuation coefficient for finite bandwidth calculations. This work provides experimental evidence supporting the validity of the subtracted forms of the acoustic K–K relations between the phase velocity and attenuation coefficient.
Transverse curvature of the acoustic slowness surface in crystal symmetry planes and associated phonon focusing cusps108(2000); http://dx.doi.org/10.1121/1.1315292View Description Hide Description
Conditions are derived for the existence of focusing cusps in ballisticphonon intensity patterns for propagation directions in crystal symmetry planes. Line caustics are known to be associated with lines of vanishing Gaussian curvature (parabolic lines) on the acoustic slowness surface, while cusps are associated specifically with points where the direction of vanishing principal curvature is parallel to the parabolic line. A parabolic line meets a crystal symmetry plane σ at a right angle, and so it is the vanishing of the slowness-surface curvature transverse to σ that conditions the existence of a cusp. A relation for the transverse curvature is derived and analyzed. It is shown that in an arbitrary symmetry plane σ there may be up to four pairs of inversion-equivalent cuspidal points for SH (out-of-plane polarized) waves, and up to eight pairs of cuspidal points associated with the in-plane polarized (usually quasi-transverse) waves. In tetragonal crystals, the symmetry planes containing the four-fold axis can have at most two pairs of cusps for the SH waves and up to six pairs of cusps for the in-plane waves. In cubic crystals, the face symmetry planes σ cannot have cuspidal points for SH waves, as is known, while four pairs of cusps for in-plane waves exist in σ if and only if the outer-most slowness sheet has a concave region embracing the four-fold axis. The points of vanishing transverse curvature on the slowness surface in symmetry planes of tetragonal and cubic media are identified by concise relations, facilitating their explicit analysis.
108(2000); http://dx.doi.org/10.1121/1.1315294View Description Hide Description
The development of Kramers–Krönig dispersion relations is typically carried out in the frequency domain. An alternative approach known as the time-causal theory develops dispersion relations for media with attenuation obeying a frequency power law through analysis in the time domain [T. L. Szabo, J. Acoust. Soc. Am. 96, 491–500 (1994)]. Although both approaches predict identical dispersion relations,it is perceived that these two approaches are distinct from each other. It is shown, however, that the time-causal theory is in essence a time-domain formulation of the Kramers–Krönig dispersion relations for the special case of media with attenuation obeying a frequency power law. Additionally, it is shown that time-domain representations of the Kramers–Krönig dispersion relations are available for a broader class of media than simply those with power law attenuation. The time-causal theory and the Kramers–Krönig dispersion relations can be viewed as two complementary, yet equivalent, approaches to the study of dispersion.
The effect of the physical properties of the tube wall on the attenuation of sound in evaporating and condensing gas–vapor mixtures108(2000); http://dx.doi.org/10.1121/1.1315293View Description Hide Description
An investigation of sound propagation in an air–water vapor mixture contained in a cylindrical tube with wet walls was recently completed [Hickey et al., J. Acoust. Soc. Am. 107, 1126–1130 (2000)]. A generalization to include the heat flux at the tube wall is presented here. The attenuation of sound in air–water vapor mixtures can be affected by the thermal properties of the tube wall. The controlling parameter is which is a proportionality constant that relates the heat flux per degree Kelvin for the substrate to that of the gas mixture. For a given amount of heat, provided by expansion and rarefaction of the working fluid, different substrates will undergo different temperature excursions. These temperature swings at the boundary change the vapor pressure of the condensate and thus reduce the diffusion of vapor to and from the boundary resulting in a reduction of the attenuation.