Volume 125, Issue 5, May 2009
- jasa express letters
- letters to the editor
- general linear 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 
- physiological acoustics 
- psychological acoustics 
- speech production 
- speech perception 
- speech processing and communication systems 
- music and musical instruments 
- bioacoustics 
- acoustical news—usa
- acoustical standards news
- reviews of acoustical patents
Index of content:
- JASA EXPRESS LETTERS
125(2009); http://dx.doi.org/10.1121/1.3104625View Description Hide Description
Milk contaminated with melamine resulted in an important health hazard that affected many babies in China recently. Ultrasonic characterization of adulterated milk may detect gross levels of melamine contamination. Sound speed and density measurements were made in skim milk as a function of melamine adulteration. An ultrasonic measurement technique to implement milk quality control is discussed.
125(2009); http://dx.doi.org/10.1121/1.3097679View Description Hide Description
Insonified microbubbles were observed in vessels within a gel with a Young’s modulus similar to that of tissue, demonstrating shape instabilities, liquid jets, and the formation of small tunnels. In this study, tunnel formulation occurred in the direction of the propagating ultrasound wave, where radiation pressure directed the contact of the bubble and gel, facilitating the activity of the liquid jets. Combinations of ultrasonic parameters and microbubble concentrations that are relevant for diagnosticimaging and drug delivery and that lead to tunnel formation were applied and the resulting tunnel formation was quantified.
125(2009); http://dx.doi.org/10.1121/1.3100641View Description Hide Description
Acoustic phased array has become an important testing tool in aeroacoustic research, where the conventional beamforming algorithm has been adopted as a classical processing technique. The computation however has to be performed off-line due to the expensive cost. An innovative algorithm with real-time capability is proposed in this work. The algorithm is similar to a classical observer in the time domain while extended for the array processing to the frequency domain. The observer-based algorithm is beneficial mainly for its capability of operating over sampling blocks recursively. The expensive experimental time can therefore be reduced extensively since any defect in a testing can be corrected instantaneously.
125(2009); http://dx.doi.org/10.1121/1.3104622View Description Hide Description
European vowels are mainly distinguished by the two lowest resonance frequencies ( and ) of the vocal tract. Once the pitch frequency exceeds the value of in normal speech, sopranos can deliberately “tune” to match . This increases loudness, uniformity of tone, and ease of singing, at some cost to intelligibility. Resonance tuning would be assisted if the pitch of the note written for a vowel corresponded with its usual range of . Analysis of several soprano roles indicates that Wagner aided the acoustics of the soprano voice at high pitch when setting text to music.
125(2009); http://dx.doi.org/10.1121/1.3104633View Description Hide Description
Finite-difference time-domain simulations of broadband sound propagation in a stratified atmosphere are presented. A method recently proposed to obtain an impedance time-domain boundary condition is implemented in a linearized Euler equations solver, which enables to study long range sound propagation over an impedance ground. Some features of the pressure pulse evolution with time are analyzed in both upward-and downward-refracting conditions, and the time-domain simulations are compared to parabolic equation calculations in the frequency domain to show the effectiveness of the proposed impedance boundary condition.
125(2009); http://dx.doi.org/10.1121/1.3113892View Description Hide Description
The pitch levels of female speech in two villages situated in a relatively remote area of China were compared. The dialects spoken in the two villages are similar to Standard Mandarin, and all subjects had learned to read and speak Standard Mandarin at school. Subjects read out a passage of roughly in Standard Mandarin, and pitch values were obtained at intervals. The overall pitch levels in the two villages differed significantly, supporting the conjecture that pitch levels of speech are influenced by a mental representation acquired through long-term exposure to the speech of others.
125(2009); http://dx.doi.org/10.1121/1.3104628View Description Hide Description
This paper shows that corrections for fluid loading must be undertaken to Earth-based calibrations for planetary probe sensors, which rely on accurate and precise predictions of mechanical vibrations. These sensors include acoustical instrumentation, and sensors for the mass change resulting from species accumulation upon oscillating plates. Some published designs are particularly susceptible (an example leading to around an octave error in the frequency calibration for Venus is shown). Because such corrections have not previously been raised, and would be almost impossible to incorporate into drop tests of probes, this paper demonstrates the surprising results of applying well-established formulations.
- LETTERS TO THE EDITOR
125(2009); http://dx.doi.org/10.1121/1.3097839View Description Hide Description
The acoustic radiation force exerted on a perfect absorber in a lossless fluid has recently been calculated for the case of a rectangular transducer emitting a static (i.e., “frozen”) ultrasonic field in the forward direction. The calculation is extended here, at least approximately, to the case of an oblique beam. This is important for measuring the ultrasonic power of scanning diagnostic devices.
125(2009); http://dx.doi.org/10.1121/1.3095807View Description Hide Description
For the purpose of investigation on acoustic properties of fractals, the sound absorption coefficients are experimentally measured by using the Menger sponge which is one of typical three-dimensional fractals. From the two-microphone measurement, the frequency range of effectively absorbing sound waves is shown to broaden with degree of fractality, which comes from the fractalproperty of the homothetic character. It is shown that experimental features are qualitatively explained by an electrical equivalent circuit model for the Menger sponge.
Quantitative evaluation of fracture healing process of long bones using guided ultrasound waves: A computational feasibility study125(2009); http://dx.doi.org/10.1121/1.3106526View Description Hide Description
The feasibility of monitoring changes in guided waves’ characteristics in a fractured long bone as modeled by a hollow cylinder and a callus at different healing stages is studied. Various guided wave modes are detected and extracted from a broadband signal at several discrete locations. The energy-spectrum and (effective velocity of the first energy peak in callus region) of guided modes are found sensitive to the healing process in different aspects and stages. The healing process may be divided into several sub-courses, each of which can be evaluated by different combinations of guided wave modes. The energy-spectrum indicates that the longitudinal tube modes L(0,1) and L(0,2) are suitable for early healing; L(0,1), L(0,2), L(0,3), and L(0,5) for midway-course; and L(0,1) and L(0,3) for late consolidation, while L(0,2), L(0,5), and L(0,8) are suitable for detecting the change in callus geometrics. The results suggest that L(0,5) for monitoring early-course; L(0,3) and L(0,7) for midway process; L(0,2) for later consolidation, and L(0,7) for monitoring geometrical variation.
- GENERAL LINEAR ACOUSTICS 
A simple method avoiding non-uniqueness in the boundary element method for acoustic scattering problem125(2009); http://dx.doi.org/10.1121/1.3111856View Description Hide Description
The boundary element method(BEM) is widely used for sound field analysis problems; however, it has a non-uniqueness problem in the exterior domain. Various methods to avoid this problem have been developed; however, these are not easily applied to the BEM. In this paper, a simple method called the “ICA-Ring (inner cavity ringing) method” is proposed for avoiding the non-uniqueness problem, and this method is applied to the BEM in both single and plural domains. The concept of the ICA-Ring method is that a scatterer in free space is hollowed as a shell and the volume is smaller; the eigenfrequencies are shifted to a higher range. Next, the mechanism of the non-uniqueness problem in plural domains and a reason of the application of the ICA-Ring method to the case of plural domains are explained. Finally, some results calculated by the BEM using the ICA-Ring method are shown. The calculational condition is that a cylinder with radius floats in two-dimensional free space. In this case, no calculational errors exist in in both single and plural domains, when the thickness of the shell is . The ICA-Ring method does not need to modify an existing computer program of conventional BEM.
- UNDERWATER SOUND 
125(2009); http://dx.doi.org/10.1121/1.3089218View Description Hide Description
The debate on the sound speed dispersion and the frequency dependence of sound attenuation in seabottoms has persisted for decades, mainly due to the lack of sufficient experimental data in the low-frequency (LF) to high-frequency speed/attenuation transition band. This paper analyzes and summarizes a set of LF measurements in shallow water that have resulted in the identification of nonlinear frequency dependence of sound attenuation in the effective media of sandy seabottoms. The long-range acoustic measurements were conducted at 20 locations in different coastal zones around the world. The seabed attenuations, inverted from different acoustic field measurements and characteristics, exhibit similar magnitude and nonlinear frequency dependence below . The resulting effective sound attenuation can be expressed by for . The corresponding average sound speed ratio at the bottom-water interface in the range is . Both the LF-field-derived sound speed and attenuation can be well described by the Biot–Stoll model with parameters that are consistent with either theoretical considerations or experimental measurements. A combination of the LF-field-inverted data with the SAX99, SAX04, and other high-frequency measurements offers a reference broadband data set in the range for sonar prediction and sediment acoustics modeling.
125(2009); http://dx.doi.org/10.1121/1.3106524View Description Hide Description
This paper applies nonlinear Bayesian inference theory to quantify the information content of reverberation and short-range propagation data, both individually and in joint inversion, to resolve seabed geoacoustic and scattering properties. The inversion of reverberation data alone is shown to poorly resolve seabed properties because of strong multi-dimensional correlations between parameters. Inversion of propagation data alone is limited by different correlations, but better constrains the geoacoustic parameters. However, propagation data are insensitive to scattering parameters such as Lambert’s scattering coefficient. In each case the parameter correlations are inherent in the physics of the forward problem (reverberation and propagation) and cannot be overcome by processing or inversion techniques; rather, the inversion of more informative data is required. This is accomplished here by joint inversion of reverberation and propagation data, weighted according to their respective maximum-likelihood error estimates. Joint inversion of reverberation and propagation data collected on the Malta Plateau (Strait of Sicily) resolves both geoacoustic and scattering properties and achieves smaller uncertainties for all parameters than obtained by the inversion of either data set alone.
125(2009); http://dx.doi.org/10.1121/1.3097770View Description Hide Description
This paper investigates the influence of water column variability on the estimates of geoacoustic model parameters obtained from matched field inversions. The acoustic data were collected on the New Jersey continental shelf during shallow water experiments in August 2006. The oceanographic variability was evident when the data were recorded. To quantify the uncertainties of the geoacoustic parameter estimates in this environment, Bayesian matched field geoacoustic inversion was applied to multi-tonal continuous wave data. The spatially and temporally varying water column sound speed is parametrized in terms of empirical orthogonal functions and included in the inversion. Its impact on the geometric and geoacoustic parameter estimates is then analyzed by the inter-parameter correlations. Two different approaches were used to obtain information about the variation of the water sound speed. One used only the profiles collected along the experimental track during the experiment, and the other also included observations collected over a larger area. The geoacoustic estimates from both the large and small sample sets are consistent. However, due to the diversity of the oceanic sound speed, more empirical orthogonal functions are needed in the inversion when more sound speed profile samples are used.
125(2009); http://dx.doi.org/10.1121/1.3097473View Description Hide Description
Herring (Clupea pallasii and C. harengus) have been observed to release gas from their bladders during vertical migration likely to adjust buoyancy and also when under strong predation pressure. Based on recently measured and modeled sound for individual fish, spectral levels are estimated for entire herring schools in the ocean for both scenarios, and the feasibility of passive detection is explored. For a typical school of migrating herring near-surface spectral levels of about rel., at are predicted. If wind conditions are calm where migrating herring are found, such as for Pacific herring in Prince William Sound, Alaska, passive detection is very likely. For an exemplary 10 metric ton compact school, peak spectral source levels of about rel. ref. are predicted, yielding a range of detection against calm wind background of about . Field measurements of potential gas-release events agree with the predictions for the compact school scenario with regard to levels and spectral shape and indicate that passive acoustic monitoring is feasible and could be a prime tool to study predator-prey interactions.
125(2009); http://dx.doi.org/10.1121/1.3097495View Description Hide Description
This paper develops an approach to three-dimensional source tracking in an uncertain ocean environment using a horizontal line array (HLA). The tracking algorithm combines matched-field focalization for environmental (seabed and water column) and source-bearing model parameters with the Viterbi algorithm for range-depth estimation and includes physical constraints on source velocity. The ability to track a source despite environmental uncertainty is examined using synthetic test cases for various track geometries and with varying degrees of prior information for environmental parameters. Performance is evaluated for a range of signal-to-noise ratios in terms of the probability of estimating a track within acceptable position/depth errors. The algorithm substantially outperforms tracking with poor environmental estimates and generally obtains results close to those obtained with exact environmental knowledge. The approach is also applied to measured narrowband data recorded on a bottom-moored HLA in shallow water (the Barents Sea) and shown to successfully track both a towed submerged source and a surface ship in cases where simpler tracking algorithms failed.
125(2009); http://dx.doi.org/10.1121/1.3106530View Description Hide Description
An absolute calibration method has been developed based on the method of three-transducer spherical-wave reciprocity for the calibration of hydrophones when immersed in sandy sediment. The method enables the determination of the magnitude of the free-field voltage receive sensitivity of the hydrophone. Adoption of a co-linear configuration allows the acoustic attenuation within the sediment to be eliminated from the sensitivity calculation. Example calibrations have been performed on two hydrophones inserted into sandy sediment over the frequency range from . In general, a reduction in sensitivity was observed, with average reductions over the frequency range tested of 3.2 and with respect to the equivalent water-based calibrations for the two hydrophones tested. Repeated measurements were undertaken to assess the robustness of the method to both the influence of the sediment disturbance associated with the hydrophone insertion and the presence of the central hydrophone. A simple finite element model, developed for one of the hydrophone designs, shows good qualitative agreement with the observed differences from water-based calibrations. The method described in this paper will be of interest to all those undertaking acoustic measurements with hydrophones immersed in sediment where the absolute sensitivity is important.
- ULTRASONICS, QUANTUM ACOUSTICS, AND PHYSICAL EFFECTS OF SOUND 
125(2009); http://dx.doi.org/10.1121/1.3106129View Description Hide Description
An ultrasonic technique for estimating viscoelastic properties of hydrogels, including engineered biological tissues, is being developed. An acoustic radiation force is applied to deform the gel locally while Doppler pulses track the induced movement. The system efficiently couples radiation force to the medium through an embedded scattering sphere. A single-element, spherically-focused, circular piston element transmits a continuous-wave burst to suddenly apply and remove a radiation force to the sphere. Simultaneously, a linear array and spectral Doppler technique are applied to track the position of the sphere over time. The complex shear modulus of the gel was estimated by applying a harmonic oscillator model to measurements of time-varying sphere displacement. Assuming that the stress-strain response of the surrounding gel is linear, this model yields an impulse response function for the gel system that may be used to estimate material properties for other load functions. The method is designed to explore the force-frequency landscape of cell-matrix viscoelasticity. Reported measurements of the shear modulus of gelatin gels at two concentrations are in close agreement with independent rheometer measurements of the same gels. Accurate modulus measurements require that the rate of Doppler-pulse transmission be matched to a priori estimates of gel properties.
125(2009); http://dx.doi.org/10.1121/1.3097767View Description Hide Description
The theory of thermoacoustic mixture separation is extended to include the effect of a nonzero axial temperature gradient. The analysis yields a new term in the second-order mole flux that is proportional to the temperature gradient and to the square of the volumetric velocity and is independent of the phasing of the wave. Because of this new term, thermoacoustic separation stops at a critical temperature gradient and changes direction above that gradient. For a traveling wave, this gradient is somewhat higher than that predicted by a simple four-step model. An experiment tests the theory for temperature gradients from 0 to 416 K/m in 50–50 He–Ar mixtures.
125(2009); http://dx.doi.org/10.1121/1.3106125View Description Hide Description
This research investigates the influence of partial reflection on the measurement of the absolute ultrasonic attenuation coefficient using contact transducers. The partial, frequency-dependent reflection arises from the thin fluid-layer interface formed between the transducer and specimen surface. It is experimentally shown that neglecting this reflection effect leads to a significant overestimation in the measured attenuation coefficient. A systematic measurement procedure is proposed that simultaneously obtains the ultrasonic signals needed to calculate both the reflection coefficient of the interface and the attenuation coefficient, without disturbing the existing coupling conditions. The true attenuation coefficient includes a correction based on the measured reflection coefficient—this is called the reflection correction. It is shown that including the reflection correction also reduces the variation (random error) in the measured attenuation coefficient. The accuracy of the proposed method is demonstrated for a material with a known attenuation coefficient. The proposed method is then used to measure the high attenuation coefficient of a cement-based material.