Volume 130, Issue 5, November 2011
- 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 
- 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 
- bioacoustics 
- acoustical news
- acoustical standards news
- reviews of acoustical patents
- part 2 special issue on the acoustics of bubbles and cavitation
- underwater sound 
- part 2 special issue on the acoustics of bubbles and cavitation
Index of content:
- JASA EXPRESS LETTERS
Cross-language acoustic similarity predicts perceptual assimilation of Canadian English and Canadian French vowels130(2011); http://dx.doi.org/10.1121/1.3632043View Description Hide Description
Monolingual Peruvian Spanish listeners identified natural tokens of the Canadian French (CF) and Canadian English (CE) /ɛ/ and /æ/, produced in five consonantal contexts. The results demonstrate that while the CF vowels were mapped to two different native vowels, /e/ and /a/, in all consonantal contexts, the CE contrast was mapped to the single native vowel /a/ in four out of five contexts. Linear discriminant analysis revealed that acoustic similarity between native and target language vowels was a very good predictor of context-specific perceptual mappings. Predictions are made for Spanish learners of the /ɛ/-/æ/ contrast in CF and CE.
130(2011); http://dx.doi.org/10.1121/1.3637364View Description Hide Description
The detection of multicomponent signals for which the components are not equidetectable is precisely investigated as a function of the level difference ΔL i/j between components. The detection thresholds are determined for a seven-tone complex signal with random starting phases masked by white noise. Level differences between the components are examined. A model for non-equidetectable conditions based on the statistical summation model is described. The improvement in detection is calculated from the level difference between components that is related to the thresholds for single components. The model predictions are in accordance with the experimental results.
130(2011); http://dx.doi.org/10.1121/1.3638223View Description Hide Description
Coherence masking protection (CMP) refers to the phenomenon in which a target formant is labeled at lower signal-to-noise levels when presented with a stable cosignal consisting of two other formants than when presented alone. This effect has been reported primarily for adults with first-formant (F1) targets and F2/F3 cosignals, but has also been found for children, in fact in greater magnitude. In this experiment, F2 was the target and F1/F3 was the cosignal. Results showed similar effects for each age group as had been found for F1 targets. Implications for auditory prostheses for listeners with hearing loss are discussed.
Cross-language specialization in phonetic processing: English and Hindi perception of /w/-/v/ speech and nonspeech130(2011); http://dx.doi.org/10.1121/1.3632048View Description Hide Description
This study examined the perceptual specialization for native-language speechsounds, by comparing native Hindi and English speakers in their perception of a graded set of English /w/-/v/ stimuli that varied in similarity to natural speech. The results demonstrated that language experience does not affect general auditory processes for these types of sounds; there were strong cross-language differences for speech stimuli, and none for stimuli that were nonspeech. However, the cross-language differences extended into a gray area of speech-like stimuli that were difficult to classify, suggesting that the specialization occurred in phonetic processing prior to categorization.
130(2011); http://dx.doi.org/10.1121/1.3638927View Description Hide Description
This paper presents a subspace approach for voice activity detection(VAD). The proposed approach is based on an embedded prewhitening scheme for the simultaneous diagonalization of the clean speech and noise covariance matrices to provide a decision rule based on likelihood ratio test in signal subspace domain. Experimental results show that the proposed subspace-based VAD algorithm outperforms the method using a Gaussian model in a conventional discrete Fourier transform domain at the low signal-to-noise conditions.
130(2011); http://dx.doi.org/10.1121/1.3642644View Description Hide Description
Preliminary measurements and numerical predictions reveal that simple, and relatively small, horns generate remarkable amplification of acoustic particle velocity. For example, below 2 kHz, a 2.5 cm conical horn has a uniform velocity amplification ratio (throat-to-mouth) factor of approximately 3, or, in terms of a decibel level, 9.5 dB. It is shown that the velocity amplification factor depends on the horn’s mouth-to-throat ratio as well as, though to a lesser degree, the horn’s flare rate. A double horn configuration provides limited additional gain, approximately an increase of up to 25%.
Waveguide invariant analysis for modeling time-frequency striations in a range-dependent environment130(2011); http://dx.doi.org/10.1121/1.3646025View Description Hide Description
The waveguide invariant is a useful parameter for understanding the behavior of interference patterns (e.g., striations in time–frequency plots) resulting from broadband acoustic sources in shallow water waveguides. It is possible to model these striations for range-dependent environments using conventional parabolic equation methods; although this approach can be computationally intensive as a full field must be created for each frequency and azimuthally dependent geometry. This letter discusses the formulation and use of a range-dependent waveguide invariant distribution that can be used to describe spectral striation patterns using a fraction of the computing power required by parabolic equation methods.
130(2011); http://dx.doi.org/10.1121/1.3645966View Description Hide Description
Printed English is highly redundant as demonstrated by readers’ facility at guessing which letter comes next in text. However, such findings have been generalized to perception of connected speech without any direct assessment of phonemic redundancy. Here, participants guessed which phoneme or printed character came next throughout each of four unrelated sentences. Phonemes displayed significantly lower redundancy than letters, and possible contributing factors (task difficulty, experience, context) are discussed. Of three models tested, phonemic guessing was best approximated by word-initial and transitional probabilities between phonemes. Implications for information-theoretic accounts of speech perception are considered.
130(2011); http://dx.doi.org/10.1121/1.3645968View Description Hide Description
A general finding of psychoacoustic studies is that detectability of a noisy signal grows less than optimally with the number N of independent observations of the signal. Competing accounts implicate internal noise common to all observations or nonoptimal decision weights given to observations. A discriminant analysis of listeners’ trial-by-trial responses in a multitone level-discrimination task favored the latter account.
130(2011); http://dx.doi.org/10.1121/1.3646024View Description Hide Description
Three-dimensional impedance maps (3DZMs) are computational models of acoustic impedance of tissue constructed from histology images. 3DZMs can be analyzed to estimate model-based quantitative ultrasound parameters such as effective scatterer diameter (ESD). In this study, 3DZMs were constructed from normal and fatty rabbit livers. Estimates of ESD were made using the fluid-filled sphere scattering model. Weighting toward smaller scatterer sizes produced ESD estimates of 7.5 ± 1.3 and 7.0 ± 0.3 μm for normal and fatty liver, respectively, approximately the size of a liver cell nucleus. This suggests the nucleus could be a primary source of scattering in liver.
130(2011); http://dx.doi.org/10.1121/1.3646026View Description Hide Description
Sounds from Longman’s beaked whale, Indopacetus pacificus, were recorded during shipboard surveys of cetaceans surrounding the Hawaiian Islands archipelago; this represents the first known recording of this species. Sounds included echolocation clicks and burst pulses. Echolocation clicks were grouped into three categories, a 15 kHz click (n = 106), a 25 kHz click (n = 136), and a 25 kHz pulse with a frequency-modulated upsweep (n = 70). The 15 and 25 kHz clicks were relatively short (181 and 144 ms, respectively); the longer 25 kHz upswept pulse was 288 ms. Burst pulses were long (0.5 s) click trains with approximately 240 clicks/s.
130(2011); http://dx.doi.org/10.1121/1.3647866View Description Hide Description
A recent study on perceptual difference in simulated concert halls showed that a concert hall renders stronger sound with more bass when the temporal envelope of a signal is preserved in the reflections [Lokki et al., J. Acoust. Soc. Am. 129, EL223–EL228 (2011)]. In the same study the lateral reflections were shown to contribute to the perceived envelopment and openness. Moreover, the listening test results suggest that lateral reflections contribute to perception of sound source distance. Here, it is shown that lateral reflections are beneficial due to their increasing effect on binaural loudness—the phenomenon known well in psychoacoustics, but not in architectural acoustics. The reflections from the side are amplified more than median plane reflections, in particular at high frequencies, due to the shape of the human head.
130(2011); http://dx.doi.org/10.1121/1.3647264View Description Hide Description
To the extent that sensorineural systems are efficient, stimulus redundancy should be captured in ways that optimize information transmission. Consistent with this principle, neural representations of sounds have been proposed to become “non-isomorphic,” increasingly abstract and decreasingly resembling the original (redundant) input. Here, non-isomorphism is tested in perceptual learning using AXB discrimination of novel sounds with two highly correlated complex acoustic properties and a randomly varying third dimension. Discrimination of sounds obeying the correlation became superior to that of sounds violating it despite widely varying physical acoustic properties, suggesting non-isomorphic representation of stimulus redundancy.
130(2011); http://dx.doi.org/10.1121/1.3647263View Description Hide Description
Listeners’ ability to discriminate interaural time difference(ITD) changes in low-frequency noise was determined as a function of differences in the noise spectra delivered to each ear. An ITD was applied to Gaussian noise, which was bandpass filtered using identical high-pass, but different low-pass cutoff frequencies across ears. Thus, one frequency region was dichotic, and a higher-frequency region monotic. ITD thresholds increased as bandwidth to one ear (i.e., monotic bandwidth) increased, despite the fact that the region of interaural spectral overlap remained constant. Results suggest that listeners can process ITD differences when the spectra at two ears are moderately different.
130(2011); http://dx.doi.org/10.1121/1.3651095View Description Hide Description
Covariation among vowel height effects on vowel intrinsic fundamental frequency (IF0), voice onset time (VOT), and voiceless interval duration (VID) is analyzed to assess the plausibility of a common physiological mechanism underlying variation in these measures. Phrases spoken by 20 young adults, containing words composed of initial voiceless stops or /s/ and high or low vowels, were produced in habitual and voluntarily increased F0 conditions. High vowels were associated with increased IF0 and longer VIDs. VOT and VID exhibited significant covariation with IF0 only for males at habitual F0. The lack of covariation for females and at increased F0 is discussed.
- LETTERS TO THE EDITOR
130(2011); http://dx.doi.org/10.1121/1.3640849View Description Hide Description
An exact integral equation approach to solving scattering from a finite section of roughness in an otherwise infinitely flat surface was described in DeSanto and Martin [J. Acoust. Soc. Am. 102, 67–77]. In this letter, the details of a numerical implementation of this approach are presented for a rough pressure release surface. An example comparing the results from this method to those from a standard, truncated integral approach is given.
130(2011); http://dx.doi.org/10.1121/1.3641402View Description Hide Description
An acoustic method based on sound transmission is proposed for deducing the static thermal permeability and the inertial factor of porous materials having a rigid frame at low frequencies. The static thermal permeability of porous material is a geometrical parameter equal to the inverse trapping constant of the solid frame [Lafarge et al., J. Acoust. Soc. Am. 102, 1995 (1997)] and is an important characteristic of the porous material. The inertial factor [Norris., J. Wave Mat. Interact. 1, 365 (1986)] describes the fluid structure interactions in the low frequency range (1-3 kHz). The proposed method is based on a temporal model of the direct and inverse scattering problems for the propagation of transient audible frequency waves in a homogeneous isotropic slab of porous material having a rigid frame. The static thermal permeability and the inertial factor are determined from the solution of the inverse problem. The minimization between experiment and theory is made in the time domain. Tests are performed using industrial plastic foams. Experimental and theoretical data are in good agreement. Furthermore, the prospects are discussed. This method has the advantage of being simple, rapid, and efficient.
130(2011); http://dx.doi.org/10.1121/1.3641410View Description Hide Description
To examine the role of perceived gender on fricative identification, a study was conducted in which listeners identified /s/-/∫/ and /s/-/θ/ continua combined with vowels produced by a man and a woman. These were acoustically modified to be consistent with different-sized vocal tracts(VT), and were presented with pictures of men or women. Listeners identified more tokens of /s/ in the /s/-/∫/ and more tokens of /θ/ in the /s/-/θ/ continuum when these sounds were combined with men’s vowels, with vowels consistent with a 17 cm VT, and with pictures of men. Results support the hypothesis that listeners incorporate information about talker gender during fricative perception.
130(2011); http://dx.doi.org/10.1121/1.3643813View Description Hide Description
The effect of temporal asymmetry on amplitude modulation detection was studied using sawtooth modulators with rising (ramped) or falling (damped) temporal envelopes within each period of modulation. For pure-tone carriers, damped modulation was more detectable than ramped modulation for a 5-kHz carrier (by a threshold difference of 3.2 dB on average) but not for a 1-kHz carrier. The threshold difference obtained at 5 kHz between the ramped and damped modulators was consistent across modulation rates (8–128 Hz). This carrier frequency dependence suggests that the effect of temporally asymmetry on modulation detection originates from envelope-based, within-channel mechanisms.
- GENERAL LINEAR ACOUSTICS 
Experimental source characterization techniques for studying the acoustic properties of perforates under high level acoustic excitation130(2011); http://dx.doi.org/10.1121/1.3641398View Description Hide Description
This paper discusses experimental techniques for obtaining the acoustic properties of in-duct samples with non-linear acoustic characteristic. The methods developed are intended both for studies of non-linear energy transfer to higher harmonics for samples only accessible from one side such as wall treatment in aircraft engine ducts or automotive exhaust systems and for samples accessible from both sides such as perforates or other top sheets. When harmonic sound waves are incident on the sample nonlinear energy transfer results in sound generation at higher harmonics at the sample (perforate) surface. The idea is that these sources can be characterized using linear system identification techniques similar to one-port or two-port techniques which are traditionally used for obtaining source data for in-duct sources such as IC-engines or fans. The starting point will be so called polyharmonic distortion modeling which is used for characterization of nonlinear properties of microwave systems. It will be shown how acoustic source data models can be expressed using this theory. Source models of different complexity are developed and experimentally tested. The results of the experimental tests show that these techniques can give results which are useful for understanding non-linear energy transfer to higher harmonics.