Volume 134, Issue 2, August 2013
- jasa express letters
- letters to the editor
- 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 
- speech processing and communication systems 
- music and musical instruments 
- bioacoustics 
- acoustical news
- book reviews
- reviews of acoustical patents
- part 2 special issue on therapeutic ultrasound
Index of content:
- JASA EXPRESS LETTERS
134(2013); http://dx.doi.org/10.1121/1.4812434View Description Hide Description
Spontaneous swallowing in dysphagic individuals has been shown to occur at a lower rate compared to healthy controls, and passive swallowing detection may function as a valid screening test to identify dysphagia in at-risk populations. To automate swallow identification, acoustic source and vocal tract features were extracted from two types of swallows and eight upper airway movements from nine healthy subjects. Swallow vs non-swallow classification accuracy was 96.3 ± 1.1%. The results provide useful methods for further development of automated tools for identification of patients with swallowing impairment.
134(2013); http://dx.doi.org/10.1121/1.4812435View Description Hide Description
The present study examined the effect of improving lexical tone identification abilities on Cantonese tone-word learning. Native English non-musicians received training on Cantonese tones before learning the meanings of words distinguished by these tones. Their results were compared to English non-musicians and musicians who received no tone training. The tone-trainees obtained a similar level of word identification proficiency as musicians by the end of training and were significantly better than non-tone trained non-musicians. These results lend support for phonetic-phonological-lexical continuity in learning because enhancing listeners' perception of lower-level tonal information significantly contributed to success in a higher-level linguistic task.
134(2013); http://dx.doi.org/10.1121/1.4812437View Description Hide Description
The integrated backscatter power (IBP) from Cochlodinium polykrikoides was measured every 15 min by a 5-MHz acoustic system during a 5-day cultivation with an irradiation cycle. IBP increased by 0.6 dB in 5 days, but varied by 0.83 dB during the irradiation cycle. The daily increase and diel variation in IBP were postulated to be affected by an increase in cell numbers and a diel variation in cell biovolume or density via photosynthesis, respectively. Cell division/separation might also affect a total variation in IBP. This study suggests that high-frequency acoustics may be a potential tool for investigating phytoplankton cell functions.
134(2013); http://dx.doi.org/10.1121/1.4812441View Description Hide Description
Numerous studies have described improvements in speech understanding when interaural time differences (ITDs) and interaural level differences (ILDs) are present. The present study aimed to investigate whether either cue in isolation can elicit spatial release from masking (SRM) in a speech-on-speech masking paradigm with maskers positioned symmetrically around the listener. Twelve adults were tested using three presentations of the Listening in Spatialized Noise–Sentences Test, with each presentation modified to contain different interaural cues in the stimuli. Results suggest that ILDs provide a similar amount of SRM as ITDs and ILDs combined. ITDs alone provide significantly less benefit.
134(2013); http://dx.doi.org/10.1121/1.4812446View Description Hide Description
This manuscript presents some recent results on directivity control and efficiency of parametric loudspeakers utilizing horns. Horns act both like an acoustic transformer and a directivity control method. An experimental device has been built and measurements have revealed that the horn has a clear influence on the audible sound levels and directivity of the parametric loudspeakers. When compared with a conventional megaphone, a much more flat frequency response is obtained and the resulting directivity is shown to be almost frequency independent.
134(2013); http://dx.doi.org/10.1121/1.4812447View Description Hide Description
In performing arts venues, the spectra of direct and reflected sound at a receiving location differ, due to seat dip effect, diffusive and absorptive surfaces, and source directivity. This paper examines the influence of differing lead and lag spectral contents on echo suppression threshold. The results indicate, that for a highpass filtered direct sound and a broadband reflection, attenuation of low frequencies initially results in an increase in echo suppression threshold, while for higher cutoff frequencies echo suppression threshold drastically decreases. For broadband direct sound and filtered reflections, the echo suppression threshold is inversely related to high frequency content.
Influence of preparation time and pitch separation in switching of auditory attention between streams134(2013); http://dx.doi.org/10.1121/1.4812439View Description Hide Description
The ability to consciously switch attention between speakers of interest is necessary for communication in many environments, especially when multiple talkers speak simultaneously. Segregating sounds of interest from the background, which is necessary for selective attention, depends on stimulus acoustics such as differences in spectrotemporal properties of the target and masker. However, the relationship between top-down attention control and bottom-up stimulus segregation is not well understood. Here, two experiments were conducted to examine the time necessary for listeners to switch auditory attention, and how the ability to switch attention relates to the pitch separation cue available for bottom-up stream segregation.
134(2013); http://dx.doi.org/10.1121/1.4812821View Description Hide Description
Lexical neighbors (words sharing phonological structure with a target word) have been shown to influence the expression of phonetic contrasts for vowels and initial voiceless consonants. Focusing on minimal pair neighbors (e.g., bud—but), this research extends this work by examining the production of voiced as well as voiceless stops in both initial and final syllable/word position. The results show minimal pair neighbors can result both in enhancement and reduction of voicing contrasts (in initial vs final position), and differentially affect voiced vs voiceless consonants. These diverse effects of minimal pair neighbors serve to constrain interactive theories of language processing.
Assessing the perceptual contributions of vowels and consonants to Mandarin sentence intelligibility134(2013); http://dx.doi.org/10.1121/1.4812820View Description Hide Description
This study investigated the perceptual contributions of vowels and consonants to Mandarin sentence intelligibility. Mandarin sentences were edited using a noise-replacement paradigm to preserve various amounts of segmental information and presented to normal-hearing listeners to recognize. The vowel-only Mandarin sentences yielded a remarkable 3:1 intelligibility advantage over the consonant-only sentences. This advantage is larger than that obtained with English sentences, suggesting that vowels may have a greater contribution to sentence intelligibility in Mandarin than in English. Although providing information redundant to contributions from vowel centers, a little vowel-consonant boundary transition would significantly improve the intelligibility of the consonant-only Mandarin sentences.
134(2013); http://dx.doi.org/10.1121/1.4812823View Description Hide Description
In the present report, the noise-shielding efficiency of balconies with ceiling-mounted reflectors on the façades of high-rise buildings is examined through full-scale field measurements. The reflectors are designed to reflect direct and diffracted waves incident on the balcony ceiling outside the balcony. Field measurements are conducted to investigate the performance of the reflectors on intermediate floors of a high-rise dwelling adjacent to a railway. The reflectors reduce railway noise by approximately 5 dB, in A-weighted sound pressure level, compared to an ordinary balcony. The noise-shielding efficiency of a balcony equipped with reflectors is greater than that of an absorbing balcony.
134(2013); http://dx.doi.org/10.1121/1.4812817View Description Hide Description
The numerical application of the statistical reduced isometry property (StRIP) and statistical null space property (SNSP) is presented and demonstrated for the design of underwater acoustic line arrays. This recent approach predicts the theoretical utility of specific subsampled arrays for compressive sensing. Three subsamplings are presented: Random, Golomb, and Wichmann. The Golomb array has no repeated spacings. The Wichmann array includes every possible interval of spacings. The SNSP is shown insensitive to the cases presented. The StRIP of the Golomb array predicts superior invertibility and is shown to perform well using at-sea data.
134(2013); http://dx.doi.org/10.1121/1.4812862View Description Hide Description
The large subaqueous sand dunes on the upper continental slope of the South China Sea are expected to couple acoustic propagating normal modes. In this letter, the criterion of adiabatic invariance is extended to the case of a waveguide possessing bedforms. Using the extended criterion to examine mode propagation over the bedforms observed in the sand dune field in 2012, results demonstrate that bedforms increase mode coupling strength such that the criterion for adiabatic propagation is exceeded for waveguides with small bedform amplitude to water depth ratios; increasing bedform amplitude enhances mode coupling. Numerical simulations confirm the extended criterion parameterization.
134(2013); http://dx.doi.org/10.1121/1.4812818View Description Hide Description
To address growing concern over the impact of anthropogenic sound on fishes, a series of experiments was conducted that exposed several fish species to high-intensity low-frequency naval sonar. This study extends auditory findings by adding largemouth bass, yellow perch, and channel catfish. No effects on hearing were found in largemouth bass and yellow perch and only small effects in channel catfish (a fish with morphological adaptations for enhanced pressure reception). Together with prior findings, these results suggest limited impact on hearing from high-intensity sonar. Susceptibility may be due to genetic stock, developmental conditions, seasonal variation, and/or buoyancy during exposure.
Applying diffuse ultrasound under dynamic loading to improve closed crack characterization in concrete134(2013); http://dx.doi.org/10.1121/1.4813847View Description Hide Description
Recent studies show the ability of diffuse ultrasound to characterize surface breaking cracks in concrete. However, derived parameters are sensitive to the presence of partially opened zones along the crack whose pattern may differ from one sample to another. The aim of this letter is to study the variation of diffuse ultrasound parameters while the sample is driven by a low frequency bending load which alternatively opens and closes the crack, allowing to access supplementary information about its morphology. The results show the sensitivity of the method for various crack depths and highlight its potential for concrete nondestructive evaluation.
134(2013); http://dx.doi.org/10.1121/1.4813802View Description Hide Description
Poor spectral resolution can be a limiting factor for hearing impaired listeners, particularly for complex listening tasks such as speech understanding in noise. Spectral ripple tests are commonly used to measure spectral resolution, but these tests contain a number of potential confounds that can make interpretation of the results difficult. To measure spectral resolution while avoiding those confounds, a modified spectral ripple test with dynamically changing ripples was created, referred to as the spectral-temporally modulated ripple test (SMRT). This paper describes the SMRT and provides evidence that it is sensitive to changes in spectral resolution.
134(2013); http://dx.doi.org/10.1121/1.4813592View Description Hide Description
The well-established static head-related transfer function (HRTF) measurement approaches using maximum length sequences and sine sweeps are compared with a recent HRTF estimation approach using normalized least mean square adaptive filters, which enables a continuous movement of the person to be measured during the recording of the excitation signal. By using continuous movement HRTF measurement, a huge amount of time for the individual HRTF estimation can be saved to create a dense HRTF database for headphone-based sound synthesis or applications such as crosstalk cancellation for loudspeaker-based sound synthesis. The different approaches are implemented and experimentally compared by objective and subjective evaluation.
134(2013); http://dx.doi.org/10.1121/1.4813846View Description Hide Description
In many oceanic waveguides, acoustic propagation is characterized by a parameter called waveguide invariant. This property is used in many passive and active sonar applications where knowledge of the waveguide invariant value is required. The waveguide invariant is classically considered as scalar but several studies show that it is better modeled by a distribution because of its dependence on frequency and mode pairs. This paper presents a new method for estimating the waveguide invariant distribution. Using the noise radiated by a distant ship and a single hydrophone, the proposed methodology allows estimating the waveguide invariant for each pair of modes in shallow water. Performance is evaluated on simulated data.
134(2013); http://dx.doi.org/10.1121/1.4813591View Description Hide Description
Sound streams were generated by randomly choosing the levels of tone pips from two different distributions, A and B. Of the 18 tone pips, the first nine were drawn from distribution A and the second nine from distribution B, or the opposite. The listeners' task was to indicate order, A-B or B-A. In two conditions the A and B distributions differed in mean (condition 1) or variance (condition 2). In contrast to an ideal observer, listeners' strategies were consistent across the two conditions. Analyses suggest that listeners relied primarily on the more intense tone pips in making their decisions.
134(2013); http://dx.doi.org/10.1121/1.4814945View Description Hide Description
Two rectangular 1/3-octave passbands were derived from different spectral regions of everyday sentences, with the intelligibility of one band approximately twice the others. Both passbands were then filtered to produce a series of narrower rectangular passbands. Each of the original 1/3-octave passbands in turn served as the fixed bandwidth “pedestal” and was paired with each of the series of narrower passbands of the other band. Remarkably, dual band intelligibilities were the same, regardless of which band served as pedestal, so the summed bandwidths determined intelligibility: The summed intelligibilities were irrelevant. Implications of this paradoxical “summed bandwidth rule” are discussed.
134(2013); http://dx.doi.org/10.1121/1.4813852View Description Hide Description
A higher-order square-root operator splitting algorithm is employed to derive a tangent linear solution for the three-dimensional parabolic wave equation due to small variations of the sound speed in the medium. The solution shown in this paper unifies other solutions obtained from less accurate approximations. Examples of three-dimensional acoustic ducts are presented to demonstrate the accuracy of the solution. Future work on the applications of associated adjoint models for acoustic inversions is proposed and discussed.