Volume 133, Issue 1, January 2013
- jasa express letters
- letters to the editor
- general linear acoustics 
- nonlinear acoustics 
- 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
Effect of perceptually irrelevant variance in head-related transfer functions on principal component analysis133(2013); http://dx.doi.org/10.1121/1.4769820View Description Hide Description
The significant amount of variance in head-related transfer functions (HRTFs) resulting from source location and subject dependencies have led researchers to use principal components analysis (PCA) to approximate HRTFs with a small set of basis functions. PCA minimizes a mean-square error, and consequently may spend modeling effort on perceptually irrelevant properties. To investigate the extent of this effect, PCA performance was studied before and after removal of perceptually irrelevant variance. The results indicate that from the sixth PCA component onward, a substantial amount of perceptually irrelevant variance is being accounted for.
Physiological evidence for auditory modulation filterbanks: Cortical responses to concurrent modulations133(2013); http://dx.doi.org/10.1121/1.4769400View Description Hide Description
Modern psychophysical models of auditory modulation processing suggest that concurrent auditory features with syllabic (∼5 Hz) and phonemic rates (∼20 Hz) are processed by different modulation filterbank elements, whereas features at similar modulation rates are processed together by a single element. The neurophysiology of concurrent modulation processing at speech-relevant rates is here investigated using magnetoencephalography. Results demonstrate expected neural responses to stimulus modulation frequencies; nonlinear interaction frequencies are also present, but, critically, only for nearby rates, analogous to “beating” in a cochlear filter. This provides direct physiological evidence for modulation filterbanks, allowing separate processing of concurrent syllabic and phonemic modulations.
133(2013); http://dx.doi.org/10.1121/1.4769399View Description Hide Description
The present study explored the acoustic characteristics of prosodic cues that indicate a speaker's reluctance when giving permission or agreement using a single word (“okay”). Eight speakers (four male, four female) produced the recorded materials that were subsequently validated through a listening experiment using 12 normal-hearing listeners. Acoustic analyses revealed that significantly longer word duration was the cue used most consistently across speakers to communicate reluctance. Voice quality, fundamental voice frequency, and intensity cues also differed significantly between the two prosodic conditions, but the manner in which these cues were applied varied greatly across speakers.
133(2013); http://dx.doi.org/10.1121/1.4769401View Description Hide Description
This letter demonstrates that the dominant coherent component of low-frequency (1 Hz < f < 20 Hz) ambient noise propagating between hydrophone pairs of the same hydroacoustic station, deployed in the deep sound channel of the Indian Ocean, is directional and mainly originates from Antarctica. However, the amplitude of the peak coherent noise arrivals, obtained using a 4-month-long averaging interval, was relatively low given the small hydrophones spacing hydrophones (<2 km). Hence, extracting similar coherent arrivals between two distinct hydroacoustic stations separated instead by thousands of kilometers for noise-based acoustic thermometry purposes seems unlikely, even using a year-long averaging.
133(2013); http://dx.doi.org/10.1121/1.4769398View Description Hide Description
The evaluation of sound pressure levels produced by submerged structures is a part of regulations on underwater noise pollution. The purpose of this work is the study of the underwater acoustic radiation of a stainless steel tube subjected to vibrations generated by a shock obtained by using a hammer. The vibrations of the tube, placed successively in air and in water, are measured by using accelerometers. In water, the acoustic radiation measurements are performed by using a hydrophone. Results are presented as frequency spectra and are confronted with results of the elastic theory.
Prior listening exposure to a reverberant room improves open-set intelligibility of high-variability sentences133(2013); http://dx.doi.org/10.1121/1.4771978View Description Hide Description
Previous studies have demonstrated that speech understanding in reverberant rooms improves when listeners are given prior exposure to the room. Results from these room-adaptation studies are limited, however, because they were conducted with materials that are not representative of the high acoustic variability observed in speech signals during everyday communication. Here, room adaptation effects were measured using an open-set speech corpus with high lexical and indexical variability and virtual auditory space techniques to simulate binaural listening in rooms. Room adaptation effects of comparable magnitude to previous studies were observed, suggesting general importance for facilitating speech intelligibility in reverberation.
Robust and low complexity localization algorithm based on head-related impulse responses and interaural time difference133(2013); http://dx.doi.org/10.1121/1.4771972View Description Hide Description
This article introduces a biologically inspired localization algorithm using two microphones, for a mobile robot. The proposed algorithm has two steps. First, the coarse azimuth angle of the sound source is estimated by cross-correlation algorithm based on interaural time difference. Then, the accurate azimuth angle is obtained by cross-channel algorithm based on head-related impulse responses. The proposed algorithm has lower computational complexity compared to the cross-channel algorithm. Experimental results illustrate that the localization performance of the proposed algorithm is better than those of the cross-correlation and cross-channel algorithms.
133(2013); http://dx.doi.org/10.1121/1.4771975View Description Hide Description
This letter applies trans-dimensional Bayesian geoacoustic inversion to quantify the uncertainty due to model selection when inverting bottom-loss data derived from wind-driven ambient-noise measurements. A partition model is used to represent the seabed, in which the number of layers, their thicknesses, and acoustic parameters are unknowns to be determined from the data. Exploration of the parameter space is implemented using the Metropolis–Hastings algorithm with parallel tempering, whereas jumps between parameterizations are controlled by a reversible-jump Markov chain Monte Carlo algorithm. Sediment uncertainty profiles from inversion of simulated and experimental data are presented.
133(2013); http://dx.doi.org/10.1121/1.4773223View Description Hide Description
Acoustic-phonetic approaches to forensic voice comparison often include human-supervised measurement of vowel formants, but the reliability of such measurements is a matter of concern. This study assesses the within- and between-supervisor variability of three sets of formant-trajectory measurements made by each of four human supervisors. It also assesses the validity and reliability of forensic-voice-comparison systems based on these measurements. Each supervisor's formant-trajectory system was fused with a baseline mel-frequency cepstral-coefficient system, and performance was assessed relative to the baseline system. Substantial improvements in validity were found for all supervisors' systems, but some supervisors' systems were more reliable than others.
133(2013); http://dx.doi.org/10.1121/1.4773199View Description Hide Description
Very long-range underwater acoustic communication (UAC) is crucial for long cruising (>1000 km) autonomous underwater vehicles (AUVs). Very long-range UAC source for AUV must exhibit high electro-acoustic efficiency (>60%) and compactness. This paper describes the Janus-Hammer Bell (JHB) transducer that has been designed for this purpose and meets those requirements. The transducer works on the 450–550 Hz bandwidth and reaches source level above 200 dB (ref. 1 μPa at 1 m) with 1 kW excitation and full immersion capability. JHB source has been used for communication experiments by the Japanese institute for marine technology (Japan Agency for Marine-Earth Science and Technology) achieving a baud rate of 100 bits/s at 1000 km.
- LETTERS TO THE EDITOR
Comparing the effect of pause duration on threshold interaural time differences between exponential and squared-sine envelopes (L)133(2013); http://dx.doi.org/10.1121/1.4768876View Description Hide Description
Recently two studies [Klein-Hennig et al., J. Acoust. Soc. Am. 129, 3856–3872 (2011); Laback et al., J. Acoust. Soc. Am. 130, 1515–1529 (2011)] independently investigated the isolated effect of pause duration on sensitivity to interaural time differences (ITD) in the ongoing stimulus envelope. The steepness of the threshold ITD as a function of pause duration functions differed considerably across studies. The present study, using matched carrier and modulation frequencies, directly compared threshold ITDs for the two envelope flank shapes from those studies. The results agree well when defining the metric of pause duration based on modulation depth sensitivity.
Comment on “Resonant acoustic scattering by swimbladder-bearing fish” [J. Acoust. Soc. Am. 64, 571–580 (1978)] (L)133(2013); http://dx.doi.org/10.1121/1.4770261View Description Hide Description
Love's model for the acoustic scattering by a spherical viscous fluid shell filled with gas and surrounded by inviscid liquid [J. Acoust. Soc. Am. 64, 571–580 (1978)] is reviewed. For certain material parameters, discrepancies are observed in Love's scattering cross section when compared with the exact solution near resonance. Those errors are corrected in this study. It is shown that there is excellent agreement between the corrected formulation and the exact solution in the resonance region where and ϵ = b/a ≥ 2.5, where k is the acoustic wavenumber, and a and b are the inner and outer radii of the shell, respectively. Errors between Love's equation and the exact solution are not significant for the case of swimbladder-bearing fish where the bubble radius is typically greater than about 0.05 m, but could be large for bubbles and gas-bearing zooplankton where the radius is less than about 0.05 m.
Comment on “A theoretical framework for quantitatively characterizing sound field diffusion based on scattering coefficient and absorption coefficient of walls” [J. Acoust. Soc. Am. 128, 1140–1148 (2010)] (L)133(2013); http://dx.doi.org/10.1121/1.4768884View Description Hide Description
The relationship between the acoustic scattering characteristics of materials and the degree of diffusion in enclosed acoustic spaces has recently attracted considerable research attention. Hanyu [J. Acoust. Soc. Am. 128(3), 1140–1148 (2010)] introduced a theoretical framework, in which the diffusion time in an enclosure is expressed as a function of a material's average scattering coefficient. In this letter, a modification of this theory is proposed. The decay process of the sound energy through scattering is divided into discrete sub-processes, specifically, a purely scattering process, and alternating scattering and specular reflections. The behavior of each process is examined for different scattering coefficients.
133(2013); http://dx.doi.org/10.1121/1.4770249View Description Hide Description
Arweiler and Buchholz [J. Acoust. Soc. Am. 130, 996–1005 (2011)] showed that, while the energy of early reflections (ERs) in a room improves speech intelligibility, the benefit is smaller than that provided by the energy of the direct sound (DS). In terms of integration of ERs and DS, binaural listening did not provide a benefit from ERs apart from a binaural energy summation, such that monaural auditory processing could account for the data. However, a diffuse speech shaped noise (SSN) was used in the speech intelligibility experiments, which does not provide distinct binaural cues to the auditory system. In the present study, the monaural and binaural benefit from ERs for speech intelligibility was investigated using three directional maskers presented from 90° azimuth: a SSN, a multi-talker babble, and a reversed two-talker masker. For normal-hearing as well as hearing-impaired listeners, the directional and/or fluctuating (speech) maskers produced a similar benefit from ERs as obtained with the diffuse SSN, suggesting a monaural integration of the ERs and the DS for both types of maskers.
- GENERAL LINEAR ACOUSTICS 
Using dispersion equation for orthotropic media to model antiplane coherent wave propagation in cracked solids133(2013); http://dx.doi.org/10.1121/1.4770257View Description Hide Description
Attention is focused on the propagation of antiplane coherent wave obliquely incident on mutually parallel and randomly distributed cracks. A fundamental question in this study concerns the ability of describing the coherent wave propagation in all directions from the knowledge of the effective material properties along the effective principal directions, only. Its relevance is illustrated by considering two cases of coherent wave propagation: homogeneous and inhomogeneous waves. For both cases, the effective phase slownesses approximated from the dispersion equation specific for orthotropic homogeneous media are compared to reference results obtained from a direct calculation considering waves obliquely incident on cracks. This work reveals that the effective stiffnesses of this dispersion equation have to be dependent on the propagation direction of the incident wave in order to make this equation consistent.
- NONLINEAR ACOUSTICS 
133(2013); http://dx.doi.org/10.1121/1.4770256View Description Hide Description
This work aims to model the acoustic radiation forces acting on an elastic sphere placed in an inviscid fluid. An expression of the axial and transverse forces exerted on the sphere is derived. The analysis is based on the scattering of an arbitrary acoustic field expanded in the spherical coordinate system centered on the spherical scatterer. The sphere is allowed to be arbitrarily located. The special case of high order Bessel beams, acoustical vortices, are considered. These types of beams have a helicoidal wave front, i.e., a screw-type phase singularity and hence, the beam has a central dark core of zero amplitude surrounded by an intense ring. Depending on the sphere's radius, different radial equilibrium positions may exist and the sphere can be set in rotation around the beam axis by an azimuthal force. This confirms the pseudo-angular moment transfer from the beam to the sphere. Cases where the axial force is directed opposite to the direction of the beam propagation are investigated and the potential use of Bessel beams as tractor beams is demonstrated. Numerical results provide an impetus for further designing acoustical tweezers for potential applications in particle entrapment and remote controlled manipulation.
- UNDERWATER SOUND 
Horizontal ducting of sound by curved nonlinear internal gravity waves in the continental shelf areas133(2013); http://dx.doi.org/10.1121/1.4770240View Description Hide Description
The acoustic ducting effect by curved nonlinear gravity waves in shallow water is studied through idealized models in this paper. The internal wave ducts are three-dimensional, bounded vertically by the sea surface and bottom, and horizontally by aligned wavefronts. Both normal mode and parabolic equation methods are taken to analyze the ducted sound field. Two types of horizontal acoustic modes can be found in the curved internal wave duct. One is a whispering-gallery type formed by the sound energy trapped along the outer and concave boundary of the duct, and the other is a fully bouncing type due to continual reflections from boundaries in the duct. The ducting condition depends on both internal-wave and acoustic-source parameters, and a parametric study is conducted to derive a general pattern. The parabolic equation method provides full-field modeling of the sound field, so it includes other acoustic effects caused by internal waves, such as mode coupling/scattering and horizontal Lloyd's mirror interference. Two examples are provided to present internal wave ducts with constant curvature and meandering wavefronts.
133(2013); http://dx.doi.org/10.1121/1.4765300View Description Hide Description
One of the difficulties in validating sediment models has been the lack of reliable low frequency dispersion measurements. A reflection method is presented that yields in situ dispersion without sediment disturbance over a broad range of frequencies and can explicitly disentangle frequency-dependent effects of vertical structure, e.g., layers and gradients. Measurements on the outer shelf from 300 to 3000 Hz show that dispersion is a strong function of depth in the sediment column. The depth and frequency-dependent results generally agree well with independent measurements on core data. Cohesive sediments in the upper few meters exhibit a nearly frequency-independent sound speed and a nearly linear frequency dependence of attenuation. In the lower part of the sediment column the sediments are more granular: the lowest layer exhibits an attenuation with a peak frequency at 1100 Hz, where its dependence below and above trends to f 2 and f 1/2, respectively. While Biot theory predicts this dependence, its underlying physical explanation, fluid flow through interstitial pores, does not seem plausible for this sediment due to the unreasonable permeability value required. Viscous grain shearing theory also predicts this dependence, but it is not known whether the parameter values are reasonable.
133(2013); http://dx.doi.org/10.1121/1.4768885View Description Hide Description
In 2009, as part of PhilSea09, the instrument platform known as Deep Sound was deployed in the Philippine Sea, descending under gravity to a depth of 6000 m, where it released a drop weight, allowing buoyancy to return it to the surface. On the descent and ascent, at a speed of 0.6 m/s, Deep Sound continuously recorded broadband ambient noise on two vertically aligned hydrophones separated by 0.5 m. For frequencies between 1 and 10 kHz, essentially all the noise was found to be downward traveling, exhibiting a depth-independent directional density function having the simple form cos θ, where θ ≤ 90° is the polar angle measured from the zenith. The spatial coherence and cross-spectral density of the noise show no change in character in the vicinity of the critical depth, consistent with a local, wind-driven surface-source distribution. The coherence function accurately matches that predicted by a simple model of deep-water, wind-generated noise, provided that the theoretical coherence is evaluated using the local sound speed. A straightforward inversion procedure is introduced for recovering the sound speed profile from the cross-correlation function of the noise, returning sound speeds with a root-mean-square error relative to an independently measured profile of 8.2 m/s.
Validation of finite element computations for the quantitative prediction of underwater noise from impact pile driving133(2013); http://dx.doi.org/10.1121/1.4768886View Description Hide Description
The acoustic radiation from a pile being driven into the sediment by a sequence of hammer strikes is studied with a linear, axisymmetric, structural acoustic frequency domain finite element model. Each hammer strike results in an impulsive sound that is emitted from the pile and then propagated in the shallow water waveguide. Measurements from accelerometers mounted on the head of a test pile and from hydrophones deployed in the water are used to validate the model results. Transfer functions between the force input at the top of the anvil and field quantities, such as acceleration components in the structure or pressure in the fluid, are computed with the model. These transfer functions are validated using accelerometer or hydrophone measurements to infer the structural forcing. A modeled hammer forcing pulse is used in the successive step to produce quantitative predictions of sound exposure at the hydrophones. The comparison between the model and the measurements shows that, although several simplifying assumptions were made, useful predictions of noise levels based on linear structural acoustic models are possible. In the final part of the paper, the model is used to characterize the pile as an acoustic radiator by analyzing the flow of acoustic energy.