Volume 119, Issue 2, February 2006
- jasa express letters
- acoustical news—usa
- acoustical news—international
- reviews of acoustical patents
- letters to the editor
- general linear acoustics 
- aeroacoustics, atmospheric sound 
- underwater sound 
- ultrasonics, quantum acoustics, and physical effects of sound 
- transduction 
- structural acoustics and vibration 
- acoustical measurements and instrumentation 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech production 
- speech perception 
- music and musical instruments 
- bioacoustics 
Index of content:
- JASA EXPRESS LETTERS
119(2006); http://dx.doi.org/10.1121/1.2152293View Description Hide Description
A spherically focused (no mirrors) capacitive-film, air-coupled ultrasonic transducer, constructed using a spherically deformed backplate and metalized polymer film, has been designed, fabricated, and its performance characterized. A diameter device has a center frequency of and a bandwidth of . Comparisons of field strength in the focal zone with theoretical calculations for a spherically focused piston show that the device achieves diffraction-limited focusing. The nominal focal point of lies within of the calculated value for this device.
Predicting perceived sharpness of broadband noise from multiple moments of the specific loudness distribution119(2006); http://dx.doi.org/10.1121/1.2152294View Description Hide Description
Equal sharpness contours for broadband noise were generated through matches made between a standard reference noise and comparison noise stimuli varying in spectral envelope. Based upon the results of the sharpness matching task, a set of 20 percussive broadband noise stimuli was constructed and presented to three subjects in a sharpness rating experiment using white noise as a standard stimulus. Predicting obtained sharpness ratings for these percussive broadband noise stimuli from first and second moments of the stimulus specific loudness distribution was more successful than conventional prediction based only upon the weighted first moment.
119(2006); http://dx.doi.org/10.1121/1.2161799View Description Hide Description
This paper investigates the applicability to sperm whales of the theory of sound radiating from a piston. The theory is applied to a physical model and to a series of sperm whale clicks. Results show that wave forms of off-axis signals can be reproduced by convolving an on-axis signal with the spatial impulse response of a piston. The angle of a recorded click can be estimated as the angle producing the spatial impulse response that gives the best match with the observation when convolved with the on-axis wave form. It is concluded that piston theory applies to sperm whale sonar click emission.
- REVIEWS OF ACOUSTICAL PATENTS
119(2006); http://dx.doi.org/10.1121/1.4736970View 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
119(2006); http://dx.doi.org/10.1121/1.2149842View Description Hide Description
This work is related to modeling of synthetic sonar images of naval mines or other objects. Considered here is the computation of high frequency scattering from the surface of a rigid 3D-object numerically represented by plane triangular facets. The far field scattered pressure from each facet is found by application of the Kirchhoff approximation. Fawcett [J. Acoust. Soc. Am.109, 1319–1320 (2001)] derived a time domain expression for the backscattered pressure from a triangular facet, but the expression encountered numerical problems at certain angles, and therefore, the effective ensonified area was applied instead. The effective ensonified area solution is exact at normal incidence, but at other angles, where singularities also exist, the scattered pressure will be incorrect. This paper presents a frequency domain expression generalized to bistatic scattering written in terms of sinc functions; it is shown that the expression improves the computational accuracy without loss of robustness.
Geometric sound propagation through an inhomogeneous and moving ocean: Scattering by small scale internal wave currents119(2006); http://dx.doi.org/10.1121/1.2159587View Description Hide Description
Ray equations appropriate for ocean acoustic propagation through an inhomogeneous and moving ocean are put forth with applications to sound scattering by internal waves. The result reveals the important role played by range dependent horizontal current shear. The Garrett–Munk internal wave model and observations of upper ocean shear and sound speed fluctuations suggest that inertial frequency upper ocean shear may play a comparable role to internal wave induced sound speed fluctuations as a source of upper ocean acoustic scattering.
Confirmation of the Biot theory for water-saturated sands at high frequencies and effects of scattering on the attenuation of sound waves119(2006); http://dx.doi.org/10.1121/1.2149770View Description Hide Description
Sound attenuation caused by the absorption and scattering of energy is studied. The Biot theory is used to predict the absorption coefficient. The scatteringattenuation applies the experimental result. The calculated attenuation coefficient is the sum of absorption and scattering components, and is in excellent agreement with data collected during the sediment acoustics experiment in 1999. This implies that the frequency dependence of the attenuation coefficient due to the fluid viscosity follows in the high-frequency range, as the Biot theory predicts. This also suggests that, at high frequencies, the attenuation coefficient is not linear in .
Comment on “The cochlear amplifier as a standing wave: ‘Squirting’ waves between rows of outer hair cells?” [J. Acoust. Soc. Am.116, 1016–1024 (2004)]119(2006); http://dx.doi.org/10.1121/1.2146087View Description Hide Description
Bell and Fletcher [J. Acoust. Soc. Am.116, 1016–1024 (Year: 2004)] proposed that one of the functions of activity of the outer hair cells (OHCs) might be a fluid-pumping action generating lateral fluid flow in the gap between the reticular membrane and the tectorial membrane and they supplied mathematical and descriptive justification for their theory which drew heavily upon the postulation (Gold, 1948) of the need for an active mechanism in the mammalian cochlea. In the 1970s there had been considerable speculation about how the inner hair cell (IHC) stereocilia are stimulated, whether they are stimulated in proportion to basilar membrane displacement or velocity or both, and whether the velocity dependence is due to subtectorial fluid flow. In 1977 experiments were conducted to investigate the possibility of subtectorial fluid flows using a dye as tracer. The work was not reported because it had been conducted at a time when visual observation of cochlear function had fallen out of favor in comparison with the more sensitive techniques thought necessary to observe submicroscopic phenomena, and secondly because it yielded a negative result. The essential details of those experiments are reported here to note for the record the extent to which this elaborate idea has already been tested.
119(2006); http://dx.doi.org/10.1121/1.2151802View Description Hide Description
A technique for modifying vocal tract area functions is developed by using sum and difference combinations of acoustic sensitivity functions to perturb an initial vocal tract configuration. First, sensitivity functions [e.g., Fant and Pauli, Proc. Speech Comm. Sem.74, 1975] are calculated for a given area function, at its specific formant frequencies. The sensitivity functions are then multiplied by scaling coefficients that are determined from the difference between a desired set of formant frequencies and those supported by the current area function. The scaled sensitivity functions are then summed together to generate a perturbation of the area function. This produces a new area function whose associated formant frequencies are closer to the desired values than the previous one. This process is repeated iteratively until the coefficients are equal to zero or are below a threshold value.
Absolute pitch among American and Chinese conservatory students: Prevalence differences, and evidence for a speech-related critical perioda)119(2006); http://dx.doi.org/10.1121/1.2151799View Description Hide Description
Absolute pitch is extremely rare in the U.S. and Europe; this rarity has so far been unexplained. This paper reports a substantial difference in the prevalence of absolute pitch in two normal populations, in a large-scale study employing an on-site test, without self-selection from within the target populations. Music conservatory students in the U.S. and China were tested. The Chinese subjects spoke the tone language Mandarin, in which pitch is involved in conveying the meaning of words. The American subjects were nontone language speakers. The earlier the age of onset of musical training, the greater the prevalence of absolute pitch; however, its prevalence was far greater among the Chinese than the U.S. students for each level of age of onset of musical training. The findings suggest that the potential for acquiring absolute pitch may be universal, and may be realized by enabling infants to associate pitches with verbal labels during the critical period for acquisition of features of their native language.
119(2006); http://dx.doi.org/10.1121/1.2159228View Description Hide Description
Two-tailpipe mufflers have become a usual solution for flow noise abatement in turbocharged Diesel engines, since the mean flow velocity at the exhaust outlet may be reduced without increasing the tailpipe diameter, which would give rise to an increase of noise associated with engine orders. In this communication, the acoustic characteristics of mufflers with two tailpipes are studied. First, a global representation of the muffler acoustics in terms of three reflection coefficients and six transmission coefficients is presented, and a procedure to obtain, from such representation, a conventional two-port transfer matrix by setting the reflection coefficient at one of the outlet pipes is provided. A procedure based on the extension of the impulse method as applied to single inlet-single outlet mufflers was devised for the experimental determination of the transmission and reflection coefficients, and experiments on a nonsymmetric oval expansion chamber allowed one to check the suitability of the representation. The results indicate that nonsymmetries in the location of the tailpipes may be relevant for the design of realistic mufflers, as they may affect the source located at each tailpipe outlet and thus the resulting exhaust noise radiated.
- GENERAL LINEAR ACOUSTICS 
Elastoacoustic model with uncertain mechanical properties for ultrasonic wave velocity prediction: Application to cortical bone evaluation119(2006); http://dx.doi.org/10.1121/1.2146110View Description Hide Description
The axial transmission technique can measure the longitudinal wavevelocity of an immersed solid. An elementary model of the technique is developed with a set of source and receivers placed in a semi-infinite fluid coupled at a plane interface with a semi-infinite solid. The acoustic fluid is homogeneous. The solid is homogeneous, isotropic, and linearly elastic. The work is focused on the prediction of the measuredvelocity (apparent velocity) when the solid is considered to have random material properties. The probability density functions of the random variables modeling each mechanical parameter of the solid are derived following the maximum entropy principle. Specific attention is paid to the modeling of Poisson’s ratio so that the second-order moments of the velocities remain finite. The stochastic solver is based on a Monte Carlo numerical simulation and uses an exact semianalytic expression of the acoustic response derived with the Cagniard–de Hoop method. Results are presented for a solid with the material properties of cortical bone. The estimated mean values and confidence regions of the apparent velocity are presented for various dispersion levels of the random parameters. A sensibility analysis with respect to the source and receivers locations is presented.
119(2006); http://dx.doi.org/10.1121/1.2159292View Description Hide Description
Two closely related problems of diffraction are solved by use of the probabilistic random walk method. The first concerns diffraction by a boundary of a half-space with a piecewise constant boundary impedance, and the second solves the problem of diffraction by a finite segment with different impedances on its sides. The solutions are represented as superpositions of predefined geometric fields with several diffracted fields, which are explicitly represented as mathematical expectations of certain functionals along the trajectories of specified random motions running across multisheet analytic manifolds associated with the boundary conditions. Numerical examples confirm the feasibility of the solutions.
119(2006); http://dx.doi.org/10.1121/1.2151769View Description Hide Description
Dispersion due to internal frictions as wave propagates is a consequence of the second principle of thermodynamics. When the wavelengths are several times higher than the mesoscopic inhomogeneities, internal diffractions can be ignored and the propagation medium can then be considered as a continuum at the scale of these wavelengths. Here, we consider the dissipation mechanism due to viscosity only. By mean of Laplace transforms both on time and space, a causal analysis leads us to a closed-form solution, which we think is the simplest analytical form. This is illustrated by searching the viscoelasticGreen’s function associated with the horizontal shear wave generated by a uniform impulsive line source in an infinite homogeneous medium, whose example is almost mathematically equivalent to the study of the scalar wave generated in viscous fluid. The described method is thus restricted to one-wave propagation problems and is probably not generally applicable when the source generates several waves. In the course to obtain a transient analytical expression of pulsed wave through a dispersive medium, this study proposes a method for transient cylindrical waves, while most previous methods concern plane waves.
A two-dimensional model of a directional microphone: Calculation of the normal force and moment on the diaphragm119(2006); http://dx.doi.org/10.1121/1.2149838View Description Hide Description
It has been shown that the parasitoid fly Ormia Ochracea exhibits exceptional sound localization ability achieved through the mechanical coupling of its eardrums [R. N. Miles et al., J. Acoust. Soc. Am.98, 3059–3070 (1995)]. Based on this biological system a new directional microphone has been designed, having as a basic element a special diaphragm undergoing a rocking motion. This paper considers a 2D model of the microphone in which the diaphragm is considered as a 2D plate having slits on the sides. The slits lead to a backing volume limited by an infinite rigid wall parallel to the diaphragm in its neutral position. The reflection and diffraction of an incoming plane wave by this system are studied to determine the resultant force and resultant moment of pressure upon the diaphragm. The results show that such a microphone will be driven better in the case of narrow slits and deep cavities.
119(2006); http://dx.doi.org/10.1121/1.2146107View Description Hide Description
Recently, an acoustic technique has been proposed to measure the scattering strength and the dynamics of weak moving scatterers in a reverberant cavity: diffusing reverberant acoustic wave spectroscopy (DRAWS). Both parameters are obtained from the correlations of the reverberated-scattered transient pressure fields for different scatterers positions. This technique is based on a diffusive field theory [de Rosny et al. , Phys. Rev. Lett., 90, 094302 (Year: 2003)]. Here, a more systematic approach of the DRAWS technique properties is presented. Moreover, an important extension is proposed using the fourth-order moment of the field, or the variance of the correlation estimator. Contrary to the correlations (second-order moment) that allow the measurement of the scattering cross section, its variance (fourth-order moment) is shown to be mainly sensitive to the scatterer displacement. The robustness of DRAWS is discussed using different configurations: a computer simulation of a moving scatterer in a two-dimensional cavity. Experiments were also carried out with a -diameter copper sphere moved by stepping motors in of water, and finally a human walking in a reverberant room.
Viscous scattering of a pressure wave: Calculation of the fluid tractions on a biomimetic acoustic velocity sensor119(2006); http://dx.doi.org/10.1121/1.2146108View Description Hide Description
In the paper we give a method for calculating the tractions (local forces) of the fluid motion determined by an incoming plane pressure wave on an artificial hair cell transducer structure. The sensing element of the transducer is a standing high aspect ratio cilium in the shape of a narrow thin curved beam (tape-like), which can be easily fabricated in micro-/nanotechnology. The method is based on considering the system of partial differential equations describing the motion of the compressible viscous fluid in an acoustic linearized approximation, and representation of the velocity field as a viscous acoustic single-layer potential. The boundary conditions, stating the cancellation of the velocity components on the solid beam, yield a two-dimensional (2-D) system of three integral equations over the beam’s surface for the traction components. In the case of a narrow cilium, the system of integral equations furnishes a system of two 1-D integral equations over the symmetry curve of the structure for obtaining the tangential and normal components of the traction. This system is solved numerically by a finite (boundary) element method. The numerical code written for solving the problem was applied to some particular structures. The last structure is similar to the trichobothrium of a spider Cupiennius salei. The results obtained show that the curvature of the hair is enhancing sensitivity to flows directed normal to the main shaft of the hair confirming the assertion of Barth et al. [Philos. Trans. R. Soc. London, Ser. B340, 445–461 (Year: 1993)].
119(2006); http://dx.doi.org/10.1121/1.2159293View Description Hide Description
Exact solution for the cumulative number of modes in a rectangular volume with reflective walls is compared with asymptotic estimates and limit cases. At low frequencies, the asymptotic expressions do not provide the correct limits and deviate appreciably from the exact results and the exact solution offers a computationally efficient alternative. The results are extended to two-dimensional regimes, membranes, plates, beams, and strings.