Volume 115, Issue 2, February 2004
- acoustical news—usa
- acoustical news—international
- 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 
- transduction 
- structural acoustics and vibration 
- noise: its effects and control 
- architectural acoustics 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech production 
- music and musical instruments 
- bioacoustics 
Index of content:
- REVIEWS OF ACOUSTICAL PATENTS
115(2004); http://dx.doi.org/10.1121/1.1642629View 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
Comment on “Background noise in piezoresistive, electret condenser, and ceramic microphones” [J. Acoust. Soc. Am. 113, 3179–3187 (2003)] (L)115(2004); http://dx.doi.org/10.1121/1.1639329View Description Hide Description
This letter comments on the paper “Background noise in piezoresistive,electretcondenser, and ceramic microphones” [J. Acoust. Soc. Am. 113, 3179–3187 (2003)], which found low-frequency-weighted noise in microphones. One possible mechanism for this type of noise is proposed.
- GENERAL LINEAR ACOUSTICS 
115(2004); http://dx.doi.org/10.1121/1.1639905View Description Hide Description
In this paper, an explicit acoustical wave propagator technique is introduced to describe the time-domain evolution of acoustical waves in two-dimensional plates. A combined scheme with Chebyshev polynomial expansion and fast Fourier transformation is used to implement the operation of the acoustical wave propagator. Through this operation, the initial wave packet at is mapped into the wave packet at any instant By comparison of the results of the exact analytical solution and the Euler numerical method, we find that this new Chebyshev–Fourier scheme is highly accurate and computationally effective in predicting the acoustical wave propagation in thin plates. This method offers an opportunity for future study of dynamic stress concentration and time-domain energy flow in coupled structures.
115(2004); http://dx.doi.org/10.1121/1.1639907View Description Hide Description
For the Pochhammer dispersion relation can be replaced by an approximate equation which can be solved to obtain the dimensionless wave number explicitly as a function of the phase velocity. This equation is similar to the corresponding equation for the Lamb modes in plate. The two types of modes are interlaced, i.e., between every pair of modes of the plate there is a longitudinal mode of cylinder and vice versa.
115(2004); http://dx.doi.org/10.1121/1.1635410View Description Hide Description
Acoustic or electromagnetic fields induced in the interior of inhomogeneous penetrable bodies by external sources can be evaluated via well-known volume integral equations. For bodies of arbitrary shape and/or composition, for which separation of variables fails, a direct attack for the solution of these integral equations is the only available approach. In a previous paper by the same authors the scalar (acoustic) field in inhomogeneous spheres of arbitrary compressibility, but with constant density, was considered. In the present one the direct hybrid (analytical-numerical) method applied to the much simpler integral equation for spheres with constant density is generalized to densities that vary with r, θ, or even φ. This extension is by no means trivial, owing to the appearance of the derivatives of both the density and the unknown function in the volume integral, a fact necessitating a more subtle and accuracy-sensitive approach. Again, the spherical shape allows use of the orthogonal spherical harmonics and of Dini’s expansions of a general type for the radial functions. The convergence of the latter, shown to be superior to other possible sets of orthogonal expansions, can be further optimized by the proper selection of a crucial parameter in their eigenvalue equation.
115(2004); http://dx.doi.org/10.1121/1.1641790View Description Hide Description
A general analytic method for calculating the scattering of sound by multiple rigid circular cylinders arranged in an arbitrary parallel configuration is presented. The soundscattered by this collection of cylinders is generated by a time-periodic, spatially distributed, axisymmetric source located within the domain of interest. A Hankel transform method is used to calculate the incident field, while separation of variables is used to obtain the scattered fields from each cylinder in the collection. The unknown scattering coefficients are determined through the use of general addition theorems that allows the various fields to be readily transformed between coordinate systems. The method is validated using various two-, three-, and four-cylinder configurations, and the number of coefficients that must be retained in the truncated series is examined. Benchmark configurations consisting of two- and three-cylinder systems with cylinders of varying radii are also presented. These solutions have been used to validate computational aeroacoustic solvers developed for complex geometries.
Coherence function and mean field of plane and spherical sound waves propagating through inhomogeneous anisotropic turbulence115(2004); http://dx.doi.org/10.1121/1.1639339View Description Hide Description
Inhomogeneity and anisotropy are intrinsic characteristics of daytime and nighttime atmospheric turbulence. For example, turbulenteddies are often stretched in the direction of the mean wind, and the turbulence statistics depends on the height above the ground. Recent studies have shown that the log-amplitude and phase fluctuations of plane and spherical sound waves are significantly affected by turbulence inhomogeneity and anisotropy. The present paper is devoted to studies of the mean sound field and the coherence functions of plane and spherical sound waves propagating through inhomogeneous anisotropicturbulence with temperature and velocity fluctuations. These statistical moments of a sound field are important in many practical applications, e.g., for source detection, ranging, and recognition. Formulas are derived for the mean sound field and coherence function of initially arbitrary waveform. Using the latter formula, we also obtained formulas for the coherence functions of plane and spherical sound waves. All these formulas coincide with those known in the literature for two limiting cases: homogeneous isotropic turbulence with temperature and wind velocity fluctuations, and inhomogeneous anisotropicturbulence with temperature fluctuations only. Using the formulas obtained, we have numerically shown that turbulence inhomogeneity significantly affects the coherence functions of plane and spherical sound waves.
115(2004); http://dx.doi.org/10.1121/1.1635414View Description Hide Description
We report an experimental study of the backscattering of a sound wave of frequency f by a surface vibrating harmonically at frequency and amplitude A in the regime where the Doppler effect overcomes bulk nonlinear effects. When the duration of the analyzedtime series of the scatteredwave is small compared to the vibration period, the power spectrum of the backscatteredwave is proportional to the probability density function of the scatterer velocity, which presents two peaks shifted from f by roughly On the contrary, when sidebands at frequencies (n integer) appear in the power spectrum, which are due to the phase modulation of the backscatteredwave induced by its reflection on a moving boundary. We use the backscattered power spectrum to validate the phase modulation theory of the Doppler effect in the latter case for and where c is the wave velocity) and we test the validity of an acoustic nonintrusive estimator of A as a function of power spectrum bandwidth and of A itself.
115(2004); http://dx.doi.org/10.1121/1.1636465View Description Hide Description
An exact analytical solution for the scattering of antiplane elastic waves by a layered elastic circular cylinder is obtained. The solution and its degenerate cases are compared with other simpler models of circular cylindrical scatterers. The effects of the geometrical and physical properties of the interphase are studied. Numerical results confirm the existence of a resonance mode in which the scatterer’s core undergoes a rigid-body motion when the outer layer of the scatterer is very compliant. This resonance mode has been attributed [Liu et al., Science 289, 1734 (2000)] to a new mechanism for the band gap formed in the extremely low frequency range for phononic crystals made of layered spherical scatterers. Numerical results also show the existence of a similar resonance mode when the outer layer of the scatterer has very high mass density.
115(2004); http://dx.doi.org/10.1121/1.1642625View Description Hide Description
The determination of the depth of surface-breaking cracks in concrete specimens using an ultrasounddiffusion technique is discussed. Experiments were carried out on precracked concrete specimens of varying crack depths (0%–40% of the specimen thickness). Contact transducers were placed at the specimen surface with source and receiver separated by the crack. Tone-burst excitations over a frequency range of 400–600 kHz were used. At these frequencies, ultrasound is scattered considerably by the heterogeneities in the concrete. In the limit of many scattering events, the evolution of energy may be modeled as a diffusion process. The arrival of the peak diffuse energy at the receiver is delayed due to the presence of crack. This delay is the prime indicator used for determining crack depth. Numerical and analytical analyses were also used for comparison. These results are in basic agreement with the experiments. In addition, these analyses are used to study the limits of this technique. In particular, it is shown that this technique is applicable to cracks greater than the scattering mean-free path, which is estimated at about 1 cm for these specimens. Aspects of practical implementation are also discussed.
115(2004); http://dx.doi.org/10.1121/1.1636464View Description Hide Description
In this paper the secular equation for the Rayleigh wave speed in an incompressible orthotropic elastic solid is obtained in a form that does not admit spurious solutions. It is then shown that inequalities on the material constants that ensure positive definiteness of the strain–energy function guarantee existence and uniqueness of the Rayleigh wave speed. Finally, an explicit formula for the Rayleigh wave speed is obtained.
On the calculation of the transmission line parameters for long tubes using the method of multiple scales115(2004); http://dx.doi.org/10.1121/1.1639323View Description Hide Description
The present paper deals with the classical problem of linear sound propagation in tubes with isothermal walls. The perturbation technique of the method of multiple scales in combination with matched asymptotic expansions is applied to derive the first-order solutions and, in addition, the second-order solutions representing the correction due to boundary layer attenuation. The propagation length is assumed to be so large that in order to obtain asymptotic solutions which extend over the whole spatial range the first-order corrections to the classical attenuation rates of the different modes come into play as well. Starting with the case of the characteristic wavelength being large compared to the characteristic dimension of the duct, the analysis is then extended to the case where both of these quantities are of the same order of magnitude. Furthermore, the transmission line parameters and the transfer functions relating the sound pressures at the ends of the duct to the axial velocities are calculated.
115(2004); http://dx.doi.org/10.1121/1.1639331View Description Hide Description
Resonantultrasoundspectroscopy relies on comparisons of experimentally determined vibrational spectra to theoretically computed spectra for the extraction of the elastic moduli of the solid samples. To determine the pressure dependence of these moduli,resonant spectra are taken for samples pressurized by a surrounding gas and knowledge of the contribution of the surface loading of the sample by the gas is needed in order to extract the intrinsic pressure dependence of the moduli. To facilitate the required comparisons, a Rayleigh–Ritz variational calculation of the vibrational spectrum is formulated which includes the loading of the solid by the pressurizing fluid. This formalism is used to compute the effect of gas loading on the vibrational spectrum of an isotropic, solid parallelepiped.
- NONLINEAR ACOUSTICS 
A new method to predict the evolution of the power spectral density for a finite-amplitude sound wave115(2004); http://dx.doi.org/10.1121/1.1639902View Description Hide Description
A method to predict the effect of nonlinearity on the power spectral density of a plane wave traveling in a thermoviscous fluid is presented. As opposed to time-domain methods, the method presented here is based directly on the power spectral density of the signal, not the signal itself. The Burgers equation is employed for the mathematical description of the combined effects of nonlinearity and dissipation. The Burgers equation is transformed into an infinite set of linear equations that describe the evolution of the joint moments of the signal. A method for solving this system of equations is presented. Only a finite number of equations is appropriately selected and solved by numerical means. For the method to be applied all appropriate joint moments must be known at the source. If the source condition has Gaussian characteristics (it is a Gaussian noise signal or a Gaussian stationary and ergodic stochastic process), then all the joint moments can be computed from the power spectral density of the signal at the source. Numerical results from the presented method are shown to be in good agreement with known analytical solutions in the preshock region for two benchmark cases: (i) sinusoidal source signal and (ii) a Gaussian stochastic process as the source condition.
115(2004); http://dx.doi.org/10.1121/1.1621858View Description Hide Description
A nonlinear model in the form of the Rayleigh–Plesset equation is developed for a gas bubble in an essentially incompressible elastic medium such as a tissue or rubberlike medium. Two constitutive laws for the elastic medium are considered: the Mooney potential, and Landau’s expansion of the strain energy density. These two constitutive laws are compared at quadratic order to obtain a relation between their respective elastic constants. Attention is devoted to the relative importance of shear stress on the bubble dynamics, allowing for the equilibrium gas pressure in the bubble to differ substantially from the pressure at infinity. The model for the bubble motion is approximated to quadratic order to assess the importance of shear stress in the surrounding medium relative to that of the gas pressure in the bubble. Relations are derived for the value of the shear wave speed at which the two contributions are comparable, which provide an assessment of when shear stress in the surrounding medium must be taken into account when modeling bubble dynamics.
- UNDERWATER SOUND 
115(2004); http://dx.doi.org/10.1121/1.1635417View Description Hide Description
The van Cittert–Zernike theorem is used to generate models for the spatialcoherence of a sound field that has been forward scattered from the sea surface. The theorem relates the spatialcoherence of an observed wave field to the distant source intensity distribution associated with this field. In this case, the sea surface upon ensonification is taken to be the source, and the sea-surface bistatic cross section corrected for transmission loss is taken as a surrogate for the source intensity distribution. Improvements in methodology for generating an estimate of the 2D autocorrelation function for sea surface waveheight variation, necessary to compute the bistatic cross section, are documented in the Appendix. Upon invoking certain approximations, simple expressions for the characteristic length scales of vertical, horizontal, and horizontal–longitudinal coherence, are derived from the theorem. The three coherence length scales identify a coherence volume for the spatialcoherence of a sound field arriving via the surface bounce channel. Models for spatialcoherence derived from the van Cittert–Zernike theorem without these approximations compare reasonably well with measurements of complex vertical coherence made at 8 kHz and 20 kHz in the East China Sea as part of the 2001 ASIAEX field program. In terms of the ASIAEX field geometries and sea-surface conditions, at frequency of 20 kHz the coherence volume is a vertical layer 0.5 m thick by 3 m in each of the two horizontal dimensions; at 8 kHz these dimensions increase by a factor of 2.5, representing the ratio of the two frequencies.
115(2004); http://dx.doi.org/10.1121/1.1640389View Description Hide Description
Recently, adaptivity was introduced to time-reversal mirror to steer the nulls, and referred to as an adaptive time-reversal mirror (ATRM) [J. S. Kim, H. C. Song, and W. A. Kuperman, J. Acoust. Soc. Am. 109, 1817–1825 (2001)]. In this study, ATRM is extended to simultaneous multiple focusing in an oceanwaveguide. The multiple focusing is achieved by imposing a set of constraints in the formulation to find the weight vectors. The algorithm is applied to the long-range underwater acoustic communication to show, via simulation, that the simultaneous pulse compression at multiple receiving locations is achieved.