Volume 133, Issue 3, March 2013
- jasa express letters
- review articles
- letters to the editor
- general linear acoustics 
- nonlinear acoustics 
- aeroacoustics, atmospheric sound 
- 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 
- speech perception 
- speech processing and communication systems 
- music and musical instruments 
- bioacoustics 
- acoustical news
- acoustical standards news
- reviews of acoustical patents
Index of content:
- JASA EXPRESS LETTERS
Synthetic array processing of ocean ambient noise for higher resolution seabed bottom loss estimation133(2013); http://dx.doi.org/10.1121/1.4774074View Description Hide Description
Predicting transmission loss in the ocean often strongly depends on the bottom loss. Bottom loss can be estimated using ocean noise and vertical array beam-forming [Harrison and Simons, J. Acoust. Soc. Am. 112, 1377–1389 (2002)]. With finite length arrays, the bottom loss estimate using this method can be smoothed due to beam widths. This paper describes how the noise coherence function can be synthetically expanded, which is similar to extending the length of an array. A full wave ocean noise model is used to demonstrate, in simulation, how this leads to improvements in the resolution of bottom loss estimates.
Gated photon correlation spectroscopy for acoustical particle velocity measurements in free-field conditions133(2013); http://dx.doi.org/10.1121/1.4789006View Description Hide Description
The measurement of acoustic pressure at a point in space using optical methods has been the subject of extensive research in airborne acoustics over the last four decades. The main driver is to reliably establish the acoustic pascal, thus allowing the calibration of microphones with standard and non-standard dimensions to be realized in an absolute and direct manner. However, the research work so far has mostly been limited to standing wave tubes. This Letter reports on the development of an optical system capable of measuring acoustic particle velocities in free-field conditions; agreement within less than 0.6 dB was obtained with standard microphone measurements during these initial experiments.
133(2013); http://dx.doi.org/10.1121/1.4789876View Description Hide Description
Many experiments in architectural acoustics require presenting listeners with simulations of different rooms to compare. Acoustic scale modeling is a feasible means to create accurate simulations of many rooms at reasonable cost. A critical component in a scale model room simulation is a receiver that properly emulates a human receiver. For this purpose, a scale model artificial head has been constructed and tested. This paper presents the design and construction methods used, proper equalization procedures, and measurements of its response. A headphone listening experiment examining sound externalization with various reflection conditions is presented that demonstrates its use for psycho-acoustic testing.
133(2013); http://dx.doi.org/10.1121/1.4789871View Description Hide Description
A methodology for the combined acoustic detection and discrimination of explosions, which uses three discriminants, is developed for the purpose of identifying weak explosion signals embedded in complex background noise. By utilizing physical models for simple explosions that are formulated as statistical hypothesis tests, the detection/discrimination approach does not require a model for the background noise, which can be highly complex and variable in practice. Fisher's Combined Probability Test is used to combine the p-values from all multivariate discriminants. This framework is applied to acoustic data from a 400 g explosion conducted at Los Alamos National Laboratory.
133(2013); http://dx.doi.org/10.1121/1.4789864View Description Hide Description
Foreign-accented speech can be difficult to understand but listeners can adapt to novel talkers and accents with appropriate experience. Previous studies have demonstrated talker-independent but accent-dependent learning after training on multiple talkers from a single language background. Here, listeners instead were exposed to talkers from five language backgrounds during training. After training, listeners generalized their learning to novel talkers from language backgrounds both included and not included in the training set. These findings suggest that generalization of foreign-accent adaptation is the result of exposure to systematic variability in accented speech that is similar across talkers from multiple language backgrounds.
133(2013); http://dx.doi.org/10.1121/1.4789863View Description Hide Description
The effects of different radial distributions of basilar membrane velocity on the fluid coupling in the cochlea are studied. Different mode shapes across the width of the basilar membrane, modeled as a beam, are simulated by assuming various boundary conditions. The results suggest that the fluid coupling is insensitive to the resulting differences in mode shape. This validates the assumption commonly made in cochlear models that the fluid coupling can be reasonably well predicted by assuming a single modal shape across the basilar membrane width, even if the exact form of the radial profile is not known.
133(2013); http://dx.doi.org/10.1121/1.4789866View Description Hide Description
This study sought to investigate the influence of temporal incoherence and inharmonicity on concurrent stream segregation, using performance-based measures. Subjects discriminated frequency shifts in a temporally regular sequence of target pure tones, embedded in a constant or randomly varying multi-tone background. Depending on the condition tested, the target tones were either temporally coherent or incoherent with, and either harmonically or inharmonically related to, the background tones. The results provide further evidence that temporal incoherence facilitates stream segregation and they suggest that deviations from harmonicity can cause similar facilitation effects, even when the targets and the maskers are temporally coherent.
133(2013); http://dx.doi.org/10.1121/1.4790820View Description Hide Description
Statistical evidence for various models relating day-night sound level (DNL) to community noise annoyance is assessed with the Akaike information criterion. In particular, community-specific adjustments such as the community tolerance level (CTL, the DNL at which 50% of survey respondents are highly annoyed) and community tolerance spread (CTS, the difference between the DNL at which 90% and 10% are highly annoyed) are considered. The results strongly support models characterizing annoyance on a community-by-community basis, rather than with complete pooling and analysis of all available surveys. The most likely model was found to be a 2-parameter logistic model, with CTL and CTS fit independently to survey data from each community.
133(2013); http://dx.doi.org/10.1121/1.4791710View Description Hide Description
An approach to hearing aid design is described, and preliminary acoustical and perceptual measurements are reported, in which an acoustic beam-forming microphone array is coupled to an eye-glasses-mounted eye-tracker. This visually guided hearing aid (VGHA)—currently a laboratory-based prototype—senses direction of gaze using the eye tracker and an interface converts those values into control signals that steer the acoustic beam accordingly. Preliminary speech intelligibility measurements with noise and speech maskers revealed near- or better-than normal spatial release from masking with the VGHA. Although not yet a wearable prosthesis, the principle underlying the device is supported by these findings.
133(2013); http://dx.doi.org/10.1121/1.4792255View Description Hide Description
Two speech functions have traditionally been ascribed to the velum: opening and closing the velopharyngeal port and providing a passive surface against which the tongue can produce oral constrictions. Contrary to this passive oral function, the present x-ray study finds that a substantial portion of the velum moves to constrict the oropharyngeal isthmus for French uvular /ʁ/. This substructure, designated the velic traverse, functions independently of the parts of the velum used for velopharyngeal port closure, thus acting as an oral articulator. An active velic traverse challenges methods for estimating vocal tract shapes based on tongue posture alone.
The impact of glottal area discontinuities on block-type vocal fold models with asymmetric tissue properties133(2013); http://dx.doi.org/10.1121/1.4790662View Description Hide Description
Block-type lumped-element models of the vocal folds are widely used for speech investigations due in part to the rich dynamics exhibited over a range of input parameters, particularly for asymmetric tissue properties. While self-consistent in derivation and application, block-type models of the vocal fold masses are inherently susceptible to non-physical aerodynamic loading conditions when vocal fold motion is highly asymmetric. A standard block-type model is compared against two modified models that disallow the non-physiological loading condition. These minor modifications toward a more physiologically relevant aerodynamic model alter the specific vibration regimes and prevalence of chaos, though bifurcations still exist.
- REVIEW ARTICLES
133(2013); http://dx.doi.org/10.1121/1.4788978View Description Hide Description
Geometrical acoustics are used as a standard model for room acoustic design and consulting. Research on room acoustic simulation focuses on a more accurate modeling of propagation effects such as diffraction and other wave effects in rooms, and on scattering. Much progress was made in this field so that wave models also (for example, the boundary element method and the finite differences in time domain) can now be used for higher frequencies. The concepts and implementations of room simulation methods are briefly reviewed. After all, simulations in architectural acoustics are indeed powerful tools, but their reliability depends on the skills of the operator who has to create an adequate polygon model and has to choose the correct input data of boundary conditions such as absorption and scattering. Very little is known about the uncertainty of this input data. With the theory of error propagation of uncertainties it can be shown that prediction of reverberation times with accuracy better than the just noticeable difference requires input data in a quality which is not available from reverberation room measurements.
- LETTERS TO THE EDITOR
133(2013); http://dx.doi.org/10.1121/1.4789893View Description Hide Description
A decision weight analysis is used to investigate transition bandwidths [Berg (2007). J. Acoust. Soc. Am. 121, 3639–2645]. The psychophysical task is similar to a standard profile analysis experiment except that the spacing of the tones comprising the stimuli is linear and very narrow (e.g., 20 Hz). An increment in the level of the central tone constitutes the signal. Pitch cues and single channel energy cues are degraded with randomization procedures. Thresholds increase as the number of tones comprising the stimulus (n) increases up to a transition bandwidth and then decrease or stay constant with further increases in n. It is proposed that the transition bandwidth reflects a discrete change in the underlying process, with a temporal process (e.g., envelope processor) dominating for stimulus bandwidths less than the transition bandwidth and a process of spectral profile analysis at wider bandwidths. Estimates of decision weights support the proposal.
Influence of the scattering and absorption coefficients on homogeneous room simulations that use a diffusion equation model133(2013); http://dx.doi.org/10.1121/1.4789928View Description Hide Description
The diffusion equation model was used for room acoustic simulations to predict the sound pressure level and the reverberation time. The technical literature states that the diffusion equation method accurately models the late portion of the room impulse response if the energy is sufficiently scattered. This work provides conclusions on the validity of the diffusion equation model for rooms with homogeneous dimensions in relation to the scattering coefficients of the boundaries. A systematic evaluation was conducted out to determine the ranges of the absorption and scattering coefficient values that result in low noticeable differences between the predictions from a geometrical acoustic model and those from the diffusion equation model.
Comment on “On Dowell's simplification for acoustic cavity-structure interaction and consistent alternatives [J. Acoust. Soc. Am.127, 22–32 (2010)]”133(2013); http://dx.doi.org/10.1121/1.4788981View Description Hide Description
This Letter describes a correction to the equations used in Ginsberg [J. Acoust. Soc. Am. 127, 22–32 (2010)] to include the rigid-body (Helmholtz) cavity mode in the modal series solution when using Dowell's method. While the correction is easy to implement, it significantly affects the results and the conclusions when using the modal series solution. Specifically, the correct formulation of Dowell's method now predicts results that agree very well with the exact solution even to the lowest frequencies.
- GENERAL LINEAR ACOUSTICS 
Acoustic attenuation, phase and group velocities in liquid-filled pipes III: Nonaxisymmetric propagation and circumferential modes in lossless conditions133(2013); http://dx.doi.org/10.1121/1.4773863View Description Hide Description
Equations for the nonaxisymmetric modes that are axially and circumferentially propagating in a liquid-filled tube with elastic walls surrounded by air/vacuum are presented using exact elasticity theory. Dispersion curves for the axially propagating modes are obtained and verified through comparison with measurements. The resulting theory is applied to the circumferential modes, and the pressures and the stresses in the liquid-filled pipe are calculated under external forced oscillation by an acoustic source. This provides the theoretical foundation for the narrow band acoustic bubble detector that was subsequently deployed at the Target Test Facility (TTF) of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL), TN.
Stabilization of time domain acoustic boundary element method for the exterior problem avoiding the nonuniqueness133(2013); http://dx.doi.org/10.1121/1.4774377View Description Hide Description
The time domain boundary element method (TBEM) to calculate the exterior sound field using the Kirchhoff integral has difficulties in non-uniqueness and exponential divergence. In this work, a method to stabilize TBEM calculation for the exterior problem is suggested. The time domain CHIEF (Combined Helmholtz Integral Equation Formulation) method is newly formulated to suppress low order fictitious internal modes. This method constrains the surface Kirchhoff integral by forcing the pressures at the additional interior points to be zero when the shortest retarded time between boundary nodes and an interior point elapses. However, even after using the CHIEF method, the TBEM calculation suffers the exponential divergence due to the remaining unstable high order fictitious modes at frequencies higher than the frequency limit of the boundary element model. For complete stabilization, such troublesome modes are selectively adjusted by projecting the time response onto the eigenspace. In a test example for a transiently pulsating sphere, the final average error norm of the stabilized response compared to the analytic solution is 2.5%.
Surface wave measurements using a single continuously scanning laser Doppler vibrometer: Application to elastography133(2013); http://dx.doi.org/10.1121/1.4789929View Description Hide Description
A continuous scanning laser Doppler vibrometry (CSLDV) obtained sweeping a single laser beam along a periodic scan pattern allows measuring surface vibrations at many points simultaneously by demultiplexing the CSLDV signal. This known method fundamentally differs from conventional scanning laser vibrometry techniques in which the laser beam is kept at a fixed point during each measurement and then moved to a new position prior to the next measurement. This article demonstrates the use of a CSLDV for measuring in a non-contact fashion the velocity of low-frequency surface waves (f < 100 Hz) propagating over soft materials, namely here gel surfaces—mimicking human body soft tissues—and skeletal muscles, to develop an affordable and noninvasive elastography modality. The CSLDV vibration measurements obtained with a single laser beam, linearly scanned over the test surface at 200 Hz over lengths up to 6 cm, were validated using an array of three fixed laser Doppler vibrometers distributed along the same scan line. Furthermore, this CSLDV setup was used to measure the increase in surface wave velocity over the biceps brachii muscle which was directly correlated to the actual stiffening of the biceps occurring while a subject was performing voluntary contractions at an increasing level.
- NONLINEAR ACOUSTICS 
133(2013); http://dx.doi.org/10.1121/1.4776178View Description Hide Description
To model nonlinear viscous dissipative motions in solids, acoustical physicists usually add terms linear in , the material time derivative of the Lagrangian strain tensor , to the elastic stress tensor derived from the expansion to the third (sometimes fourth) order of the strain energy density . Here it is shown that this practice, which has been widely used in the past three decades or so, is physically wrong for at least two reasons and that it should be corrected. One reason is that the elastic stress tensor is not symmetric while is symmetric, so that motions for which will give rise to elastic stresses that have no viscous pendant. Another reason is that is frame-invariant, while is not, so that an observer transformation would alter the elastic part of the total stress differently than it would alter the dissipative part, thereby violating the fundamental principle of material frame indifference. These problems can have serious consequences for nonlinear shear wave propagation in soft solids as seen here with an example of a kink in almost incompressible soft solids.
Rotation of non-spherical micro-particles by amplitude modulation of superimposed orthogonal ultrasonic modes133(2013); http://dx.doi.org/10.1121/1.4776209View Description Hide Description
Contactless rotation of non-spherical particles has been modeled and experimentally achieved using ultrasonic manipulation. For this purpose an acoustic radiation torque was generated by a time-varying pressure field resulting in a change of orientation of the potential well. The rotation method is based on amplitude modulation of two orthogonal ultrasonic modes. The force potential field has been used to evaluate the different modes and actuations to achieve rotation. Experiments have been performed in micro devices with copolymer particles and glass fibers at frequencies in the megahertz range. A continuous rotation was successfully demonstrated and the method allowed to stop the rotation at arbitrary angular positions.