Volume 132, Issue 4, October 2012
- jasa express letters
- letters to the editor
- education in acoustics 
- 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 
- acoustical measurements and instrumentation 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech production 
- speech perception 
- music and musical instruments 
- bioacoustics 
- acoustical news
- reviews of acoustical patents
- part 2 special issue on acoustic metamaterials
Index of content:
- JASA EXPRESS LETTERS
132(2012); http://dx.doi.org/10.1121/1.4748269View Description Hide Description
The coincidence effect is manifested by maximal sound transmission at angles at which trace wave number matching occurs. Coincidence effect theory is well-defined for unbounded thin plates using plane-wave excitation. However, experimental results for finite bars are known to diverge from theory near grazing angles. Prior experimental work has focused on pulse excitation. An experimental setup has been developed to observe coincidence using continuous- wave excitation and phased-array methods. Experimental results with an aluminum bar exhibit maxima at the predicted angles, showing that coincidence is observable using continuous waves. Transmission near grazing angles is seen to diverge from infinite plate theory.
132(2012); http://dx.doi.org/10.1121/1.4748281View Description Hide Description
A physics-based method for beamforming signals measured on a horizontal array is developed with an application to underwater active sonar systems. The proposed striation-based beamformer coherently combines the pressure from each element in the array at different frequencies, and these frequencies are selected based on a striation hypothesis. The linear frequency shift and corresponding phase term introduced in the array weight vector accounts for multipath-induced fading, producing beam output with increased signal gain. The method is demonstrated using data collected on an array towed in the North Atlantic. The combination of the striation-based beamformer with the waveguide invariant concept to improve tracker performance is discussed.
Corrected contact dynamics for the Steinecke and Herzel asymmetric two-mass model of the vocal folds132(2012); http://dx.doi.org/10.1121/1.4734013View Description Hide Description
The simplified two-mass model of human vocal folds, proposed by Steinecke and Herzel [J. Acoust. Soc. Am. 97(3), 1874–1884 (1995)], has seen widespread use throughout the speech community. Herein, an error is corrected in the contact loadings on colliding vocal folds with asymmetric tissue properties, as arises clinically in cases of unilateral paralysis. A revised contact model is proposed that remediates the erroneous asymmetric contact forces. The vibration regime map presented in Steinecke and Herzel illustrating the dynamical behavior of the system is revised using the corrected collision model.
132(2012); http://dx.doi.org/10.1121/1.4748343View Description Hide Description
This study aims to evaluate how speech quality is affected by noise which varies in modulation from 0% (the lowest correlation with the speech envelope) to 100% (the highest correlation with the speech envelope). Using a scaled paired-comparison forced-choice procedure, ten normal-hearing listeners rated overall preference, noisiness, and distortion of speech stimuli with different noise modulation percentages at 0, 10, and 20 dB signal-to-noise ratios. As noise modulation percentage increased, ratings for overall preference increased, ratings for distortion increased, and ratings for noisiness decreased. The noise modulation effects on quality ratings were significant, even at the same signal-to-noise ratio.
132(2012); http://dx.doi.org/10.1121/1.4747273View Description Hide Description
A range estimation scheme is proposed when a moving object is located within the forward scattering coverage. It is based on acoustic field aberrations of the stable arrival caused by forward scattering of the moving object. The durations of acoustic field aberration are measured by transmitting a signal continuously, and then the range of the moving object is estimated if a priori knowledge of the moving speed is supposed to be known. The acoustic field aberrations of the experimental data are clearly observed after matched filtering, and the estimated ranges of the object agree well with the true values.
132(2012); http://dx.doi.org/10.1121/1.4747815View Description Hide Description
During a recent experiment in Kauai, Hawaii, reciprocal transmissions were conducted between two acoustic transceivers mounted on the seafloor at a depth of 100 m. The passage of moving surface wave crests was shown to generate focused and intense coherent acoustic returns, which had increasing or decreasing delay depending on the direction of propagation relative to the direction of surface wave crests. It is shown that a rough surface two-dimensional parabolic equation model with an evolving sea surface can produce qualitative agreement with data for the dynamic surface returns.
132(2012); http://dx.doi.org/10.1121/1.4751989View Description Hide Description
Phase velocity and normalized broadband ultrasound attenuation (nBUA) were measured in 22 marrow-filled and water-filled bovine femoral trabecular bone samples. Replacement of marrow by water led to a significant increase in the mean phase velocity of 47 ± 12 m/s (+3.1%), but a decrease in the mean nBUA of 10.4± 2.9 dB/cm/MHz (−38.9%). All the ultrasonicproperties in the marrow-filled and water-filled samples exhibited significant negative Pearson's correlation coefficients of r = −0.87 to −0.92 with porosity. High correlations were also observed between pairs of the ultrasonicproperties, with r = 0.85 to 0.93.
132(2012); http://dx.doi.org/10.1121/1.4747325View Description Hide Description
This paper proposes a statistical voice activity detection method in a high-dimensional kernel feature space by a nonlinear mapping. A Gaussian density model is presented using kernel principal component analysis to represent the nonlinear characteristics of the speech signal. The proposed approach offers a decision rule based on a multiple observation likelihood ratio test in the kernel space.
Passive acoustic detection of closed-circuit underwater breathing apparatus in an operational port environment132(2012); http://dx.doi.org/10.1121/1.4751985View Description Hide Description
Divers constitute a potential threat to waterside infrastructures. Active diver detectionsonars are available commercially but present some shortcomings, particularly in highly reverberant environments. This has led to research on passive sonar for diver detection. Passive detection of open-circuit UBA (underwater breathing apparatus) has been demonstrated. This letter reports on the detection of a diver wearing closed-circuit UBA (rebreather) in an operational harbor. Beamforming is applied to a passive array of 10 hydrophones in a pseudo-random linear arrangement. Experimental results are presented demonstrating detection of the rebreather at ranges up to 120 m and are validated by GPS ground truth.
132(2012); http://dx.doi.org/10.1121/1.4747816View Description Hide Description
This letter introduces an algorithm for automatic detection of minke whale boing sounds. This method searches for frequency features of boings without calculating the continuous spectrogram of the data, thereby reducing computational time. The detector has been tested on 8 h of acoustic data recorded at the Station ALOHA Cabled Observatory in March 2007. This dataset was previously analyzed using the cross-correlation detector of xbat and was verified by a human listener, as reported in Oswald et al. [(2011). J. Acoust. Soc. Am. 129, 3353–3360]. A comparison of results indicates that the detector introduced here generates fewer false alarms, and it recognizes low-SNR calls that are missed by xbat.
Aperiodicity effects on sound transmission through arrays of identical cylinders perpendicular to the ground132(2012); http://dx.doi.org/10.1121/1.4751991View Description Hide Description
Results of laboratory measurements of sound transmission through 5 × 10 arrays of meter long polyvinyl chloride pipes with lattice constants of 5 and 10 cm with filling fractions of 13% and 50% located either on medium density fibreboard or a layer of felt are reported. Ground effects and sonic crystal effects are found to be additive. Measurements and predictions show that, while there is little broadband advantage in a periodic configuration compared with a random one, a quasi-periodic arrangement in which the perturbation has a standard deviation equal to the scatterer diameter gives the best overall attenuation.
132(2012); http://dx.doi.org/10.1121/1.4751987View Description Hide Description
Codebook-based speech enhancement methods that use trained codebooks of speech and noise spectra provide good performance even under non-stationary noise conditions. A drawback, however, is their high computational cost. For every pair of speech and noise codebook vectors, a likelihood score indicating how well that pair matches the observation is computed. In this paper, a method that identifies and performs only relevant likelihood computations by imposing a hierarchical structure on the speech codebook is proposed. The performance of the proposed method is shown to be close to that of the original scheme but at a significantly lower computational cost.
Comparing live to recorded speech in training the perception of spectrally shifted noise-vocoded speech132(2012); http://dx.doi.org/10.1121/1.4754432View Description Hide Description
Two experimental groups were trained for 2 h with live or recorded speech that was noise-vocoded and spectrally shifted and was from the same text and talker. These two groups showed equivalent improvements in performance for vocoded and shifted sentences, and the group trained with recorded speech showed consistently greater improvements than untrained controls. Another group trained with unshifted noise-vocoded speech improved no more than untrained controls. Computer-based training thus appears at least as effective as labor-intensive live-voice training for improving the perception of spectrally shifted noise-vocoded speech, and by implication, for training of users of cochlear implants.
132(2012); http://dx.doi.org/10.1121/1.4754429View Description Hide Description
Rising underwater noise levels from shipping have raised concerns regarding chronic impacts to marine fauna. However, there is a lack of consensus over how to average local shipping noise levels for environmental impact assessment. This paper addresses this issue using 110 days of continuous data recorded in the Strait of Georgia, Canada. Probability densities of 1-s samples in selected 1/3 octave bands were approximately stationary across one-month subsamples. Median and mode levels varied with averaging time. Mean sound pressure levels averaged in linear space, though susceptible to strong bias from outliers, are most relevant to cumulative impact assessment metrics.
- LETTERS TO THE EDITOR
132(2012); http://dx.doi.org/10.1121/1.4746030View Description Hide Description
In a recent study, Kastelein et al. [(2010) J. Acoust. Soc. Am. 127, 1135–1145] reported auditory integration times for harbor seals (Phoca vitulina) exceeding 3000 ms for 200 Hz tonal signals. This finding is unexpected and potentially significant given that time constants measured in mammals for tones above 1 kHz are typically less than 500 ms. To further explore this result, the hearing of another harbor seal was measured in air and water for 200 Hz tones with durations of 500 and 2500 ms. Threshold comparisons, as well as reaction time measures, revealed no gain in audibility as signal duration increased above 500 ms.
132(2012); http://dx.doi.org/10.1121/1.4746021View Description Hide Description
The approach proposed here requires that for each parameter combination in a search space only a minimum processor value (over frequencies) be retained. Thus all frequencies considered at that point will have processor values at least as great as the final value. Consequently, (1) the frequency most sensitive to a parameter dominates the search automatically and (2) resolution has improved with major sidelobe reduction. The method is intended primarily for geoacoustic inversion methods (where the signal-to-noise levels are high).
Comment on plate modal wavenumber transforms in Sound and Structural Vibration [Academic Press (1987, 2007)] (L)132(2012); http://dx.doi.org/10.1121/1.4747012View Description Hide Description
The wavenumber transform for rectangular, simply supported, isotropic thin plates has been rederived to correct a technical error found in the text Sound and Structural Vibration (Academic Press, 1985/2007) by Fahy/Fahy and Gardonio. The text states that the modal wavenumber corresponds to the peak of the wavenumber spectrum. While this is approximately true for higher-order modes, it does not hold for lower-order modes due to coupling between positive and negative wavenumber energy. The modal wavenumber is shown to be related to the zeros in the wavenumber spectrum by an integer multiple of normalized by the plate length.
132(2012); http://dx.doi.org/10.1121/1.4747019View Description Hide Description
An alternative formula for determining the volume-referenced, projector-transducer figure of merit, FOM v , is developed allowing an evaluation based on well known parameters that may be readily calculated or measured. This formula is also reduced to the special case of piezoelectric or magnetostrictive materials, allowing a FOM v comparison of transducermaterials in addition to an evaluation of specific transducer designs. Sample results are given for transducermaterials alone and a PZT-8 driven modal projector transducer operated in the monopole mode.
132(2012); http://dx.doi.org/10.1121/1.4748583View Description Hide Description
A lumped parameter equivalent circuit basis for calculating and allocating heat power sources in a transducer is presented along with experimental results. The simple model allows heat power calculations at resonance based on readily attainable parameters for transducers with uniform fields. Measured and finite element analysis of steady state thermal results are compared for the monopole mode of the single crystal driven modal transducer projector. The model serves as a physical and computational aid in the evaluation of piezoelectric transducer heating and may be used for evaluating highly coupled single crystal as well as ceramicpiezoelectric transducers.
Extraction of statistical properties of the point source response of a reverberant plate and application to parameter estimation (L)132(2012); http://dx.doi.org/10.1121/1.4750495View Description Hide Description
The point source response of a reverberant solid plate is modeled through a nonstationary Poisson process based on the image-source method. The theoretical expectation of the envelope is then derived, taking into account the dispersive nature of plate waves, and validated by numerical results. Least-square curve-fitting applied to an ensemble average over N realizations can then be used to identify useful parameters such as wave velocity, plate surface, or source-receiver distance. It is shown that even values of N down to 1 (no averaging) allow a satisfying identification. Application to the estimation of the source-receiver distance using a single sensor is finally highlighted to illustrate the promising potentialities of the measurement principle proposed.