Volume 136, Issue 2, August 2014
- jasa express letters
- letters to the editor
- general linear acoustics 
- nonlinear acoustics 
- aeroacoustics, atmospheric sound 
- underwater sound 
- ultrasonics, quantum acoustics, and physical effects of sound 
- noise: its effects and control 
- acoustical measurements and instrumentation 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech production 
- speech perception 
- speech processing and communication systems 
- music and musical instruments 
- animal bioacoustics 
- book reviews
- reviews of acoustical patents
Index of content:
- JASA EXPRESS LETTERS
136(2014); http://dx.doi.org/10.1121/1.4885486View Description Hide Description
Monostatic circular synthetic aperture sonar (CSAS) images are formed by processing azimuthal angle dependent backscattering from a target at a fixed distance from a collocated source/receiver. Typical CSAS imaging algorithms [Ferguson and Wyber, J. Acoust. Soc. Am. 117, 2915–2928 (2005)] assume scattering data are taken in the farfield. Experimental constraints may make farfield measurements impractical and thus require objects to be scanned in the nearfield. Left uncorrected this results in distortions of the target image and in the angular dependence of features. A fast approximate Hankel function based algorithm is presented to convert nearfield data to the farfield. Images and spectrograms of an extended target are compared for both cases.
136(2014); http://dx.doi.org/10.1121/1.4885480View Description Hide Description
Killer whales project short broadband biosonar clicks. The broadband nature of the clicks provides good temporal resolution of echo highlights and allows for the discriminations of salmon prey. The echoes contain many highlights as the signals reflect off different surfaces and parts of the fish body and swim bladder. The temporal characteristics of echoes from salmon are highly aspect dependent and six temporal parameters were used in a support vector machine to discriminate between species. Results suggest that killer whales can classify salmon based on their echoes and provide some insight as to which features might enable the classification.
136(2014); http://dx.doi.org/10.1121/1.4885541View Description Hide Description
For the analysis of non-stationary signals generated by a non-linear process like fault of an induction motor, empirical mode decomposition (EMD) is the best choice as it decomposes the signal into its natural oscillatory modes known as intrinsic mode functions (IMFs). However, some of these oscillatory modes obtained from a fault signal are not significant as they do not bear any fault signature and can cause misclassification of the fault instance. To solve this issue, a novel IMF selection algorithm is proposed in this work.
136(2014); http://dx.doi.org/10.1121/1.4885485View Description Hide Description
The response of the boundary layer over an airfoil with cavity to external acoustic forcing, across a sweep of frequencies, was measured. The boundary layer downstream of the cavity trailing edge was found to respond strongly and selectively at the natural airfoil tonal frequencies. This is considered to be due to enhanced feedback. However, the shear layer upstream of the cavity trailing edge did not respond at these frequencies. These findings confirm that an aeroacoustic feedback loop exists between the airfoil trailing edge and a location near the cavity trailing edge.
136(2014); http://dx.doi.org/10.1121/1.4885540View Description Hide Description
The influence of convection and temperature on the radiation impedance of an open duct termination exhausting a hot gas is commonly described by a complex theory. A simplified analytical expression is proposed for low frequencies. Both models assume a free jet with uniform velocity bounded by infinitely thin shear layers. The convective velocity that should be assumed when applying these models to a non-uniform outflow is uncertain. A simplified version of the so-called Vortex Sound Theory demonstrates that the convective velocity one should assume is lower than the jet centerline velocity.
136(2014); http://dx.doi.org/10.1121/1.4885481View Description Hide Description
A transfer matrix method to predict absorption coefficient and transmission loss of parallel assemblies of materials which can be expressed by a 2 × 2 transfer matrix was published recently. However, the usual method based on the sum of admittances is largely used to predict also surface admittance of parallel assemblies. This paper aims to highlight differences between both methods through three examples on a parallel assembly backed by (1) a rigid wall, (2) an air cavity, and (3) an anechoic termination.
136(2014); http://dx.doi.org/10.1121/1.4885771View Description Hide Description
This study compares bone conduction (BC) thresholds obtained with two bone vibrators (BV): The Radioear B71 and an advanced BV, the Radioear B81. B81 has less distortion and is capable of higher output levels. Two tests with 20 normal hearing subjects were conducted to determine if the low distortion of B81 offers any advantages for audiometry. Hearing threshold differences between B71 and B81 are only significant at 250 Hz for levels between 20 dB hearing level (HL) and 30 dB HL. At other frequencies and higher levels, where B81 also performs with less distortion than B71, tactile responses interfere before B81 can be advantageous.
136(2014); http://dx.doi.org/10.1121/1.4885479View Description Hide Description
A planewave, incident on a panel, produces an acoustic trace wavelength that propagates along the surface of the panel. The trace wavelength excites the panel into vibration, creating structural waves within the panel that propagate. These structural waves can be purposely Bragg scattered, creating replicas of the trace wavenumber. The replicas are shifted in wavenumber precisely by the inverse of the periodic separation distance . Hence, in principle, it should be possible to resolve the acoustic trace wavelength from one of the shifted replicas of the panel's response. The incident angle can then be ascertained from the replicated trace wavelengths.
136(2014); http://dx.doi.org/10.1121/1.4885483View Description Hide Description
Tone normalization has been observed in Mandarin listeners, who contrastively adjust tone recognition using context pitch cues. This study tested the effect of context duration on Mandarin tone normalization. The target tones varied from Tone 1 (high-flat) to Tone 2 (mid-rising). The preceding phrase was modified to have different durations with 160- or 200-Hz mean fundamental frequencies (F0s). The results showed that the high-F0 context elicited significantly more Tone-2 responses than the low-F0 context, even when the contexts were 125 ms. The contrastive context effect saturated with the 250-ms contexts, indicating a 250-ms critical context duration for robust tone normalization.
136(2014); http://dx.doi.org/10.1121/1.4885482View Description Hide Description
Aging affects temporal characteristics of speech. It is still a question how these changes occur in different speech styles which require various cognitive skills. In this paper speech rate, articulation rate, and pauses of 20 young and 20 old speakers are analyzed in four speech styles: spontaneous narrative, narrative recalls, a three-participant conversation, and reading aloud. Results show that age has a significant effect only on speech rate, articulation rate, and frequency of pauses. Speech style has a higher effect on temporal parameters than speakers' age.
136(2014); http://dx.doi.org/10.1121/1.4885768View Description Hide Description
This paper proposes an automatic acoustic-phonetic method for estimating voice-onset time of stops. This method requires neither transcription of the utterance nor training of a classifier. It makes use of the plosion index for the automatic detection of burst onsets of stops. Having detected the burst onset, the onset of the voicing following the burst is detected using the epochal information and a temporal measure named the maximum weighted inner product. For validation, several experiments are carried out on the entire TIMIT database and two of the CMU Arctic corpora. The performance of the proposed method compares well with three state-of-the-art techniques.
136(2014); http://dx.doi.org/10.1121/1.4890197View Description Hide Description
This paper implements a weighted ensemble Kalman filter for tracking time-evolving sound speed profiles. The approach first updates the particles following the procedure of the ensemble Kalman filter and then resamples the updated particles according to their importance weights. The weights are evaluated by the classical geoacoustic inversion likelihood obtained from the Bartlett power objective functions. Example illustrates that the new method outperforms the ensemble with a comparable computational load.
136(2014); http://dx.doi.org/10.1121/1.4890202View Description Hide Description
Acoustical coupling between architectural spaces can be implemented by sliding or hinged doors. This study compares the effects of these variable coupling area designs on the sound field using temporal energy decay curve analysis. Varying the aperture size alters the multi-slope decay curve properties such as the decay rate of each slope and their point of intersection (time and level). A predictive model is proposed, based on a geometrical approach and statistical theory for coupled volumes. Differences between scale model measurements and analytical predictions are quantified by means of deviations of acoustical parameters; reasonable agreement is found.
Audiovisual training is better than auditory-only training for auditory-only speech-in-noise identification136(2014); http://dx.doi.org/10.1121/1.4890200View Description Hide Description
The effects of audiovisual versus auditory training for speech-in-noise identification were examined in 60 young participants. The training conditions were audiovisual training, auditory-only training, and no training (n = 20 each). In the training groups, gated consonants and words were presented at 0 dB signal-to-noise ratio; stimuli were either audiovisual or auditory-only. The no-training group watched a movie clip without performing a speech identification task. Speech-in-noise identification was measured before and after the training (or control activity). Results showed that only audiovisual training improved speech-in-noise identification, demonstrating superiority over auditory-only training.
136(2014); http://dx.doi.org/10.1121/1.4890205View Description Hide Description
In recent years, the concept of the Acoustic Black Hole has been developed as an efficient passive, lightweight absorber of bending waves in plates and beams. Theory predicts greater absorption for a higher thickness taper power. However, a higher taper power also increases the violation of an underlying theory smoothness assumption. This paper explores the effects of high taper power on the reflection coefficient and spatial change in wave number and discusses the normalized wave number variation as a spatial design parameter for performance, assessment, and optimization.
136(2014); http://dx.doi.org/10.1121/1.4890213View Description Hide Description
The solutions of pattern synthesis are derived for circular sensor arrays based on the criterion of minimizing the mean square error between the desired and synthesized beampatterns. Specifically, the optimal weighting vector, the output beam, and the minimum mean square error are all expressed in closed-form exactly when the desired beampattern is properly formulated. These results provide a more effective and convenient scheme for designing practical frequency-invariant beamformers. Simulations and experimental results demonstrate the performance of the proposed approach.
136(2014); http://dx.doi.org/10.1121/1.4890664View Description Hide Description
Localizing a source of radial movement at moderate range using a single hydrophone can be achieved in the reliable acoustic path by tracking the time delays between the direct and surface-reflected arrivals (D-SR time delays). The problem is defined as a joint estimation of the depth, initial range, and speed of the source, which are the state parameters for the extended Kalman filter (EKF). The D-SR time delays extracted from the autocorrelation functions are the measurements for the EKF. Experimental results using pseudorandom signals show that accurate localization results are achieved by offline iteration of the EKF.
136(2014); http://dx.doi.org/10.1121/1.4890175View Description Hide Description
The perceived duration of 1-kHz pure tones with increasing or decreasing intensity profiles was measured. The ratio between the down- and up-ramp durations at equal subjective durations was examined as a function of the sound duration (50, 100, 200, 500, 1000, 2000 ms). At 50 and 100 ms, the ratio was constant and equaled about 1.7, then it logarithmically decreased from 100 to 1000 ms to reach a constant value of 1 at 1 and 2 s. The different mechanisms proposed in the literature to explain the perceived duration asymmetry between up-ramp and down-ramp were discussed in the light of the dependence of this ratio on duration.
136(2014); http://dx.doi.org/10.1121/1.4890207View Description Hide Description
Many features of auditory perception are positively altered in musicians. Traditionally auditory mechanisms in musicians are investigated using the Western-classical musician model. The objective of the present study was to adopt an alternative model—Indian-classical music—to further investigate auditory temporal processing in musicians. This study presents that musicians have significantly lower across-channel gap detection thresholds compared to nonmusicians. Use of the South Indian musician model provides an increased external validity for the prediction, from studies on Western-classical musicians, that auditory temporal coding is enhanced in musicians.
136(2014); http://dx.doi.org/10.1121/1.4890196View Description Hide Description
The motions of a rigid and unconstrained prolate spheroid subjected to plane sound waves are computed using preliminary analytic derivation and numerical approach. The acoustically induced motions are found comprising torsional motion as well as translational motion in the case of acoustic oblique incidence and present great relevance to the sound wavelength, body geometry, and density. The relationship between the motions and acoustic particle velocity is obtained through finite element simulation in terms of sound wavelengths much longer than the overall size of the prolate spheroid. The results are relevant to the design of inertial acoustic particle velocity sensors based on prolate spheroids.