- jasa express letters
- letters to the editor
- general linear acoustics 
- nonlinear acoustics 
- aeroacoustics, atmospheric sound 
- underwater 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 standards news
- acoustical news
- reviews of acoustical patents
Index of content:
Volume 132, Issue 5, November 2012
- JASA EXPRESS LETTERS
132(2012); http://dx.doi.org/10.1121/1.4754419View Description Hide Description
This paper presents an analysis of the acoustic emissions emitted by an underway REMUS-100 autonomous underwater vehicle(AUV) that were obtained near Honolulu Harbor, HI using a fixed, bottom-mounted horizontal line array (HLA). Spectral analysis,beamforming, and cross-correlation facilitate identification of independent sources of noise originating from the AUV. Fusion of navigational records from the AUV with acoustic data from the HLA allows for an aspect-dependent presentation of calculated source levels of the strongest propulsion tone.
132(2012); http://dx.doi.org/10.1121/1.4754808View Description Hide Description
The potential operating conditions of acoustic dual-negative refraction (ADNR) are investigated by band structuretheory for scatterers with different shapes and symmetries. Specifically, two types of lattices (triangular and honeycomb) and four different shapes of scatterers (circle, hexagon, square and triangle) are considered. Based on the generation mechanism of the ADNR effect, which is dependent on the frequency of the incident wave at the overlapping second and third Bloch bands, the optimum operating frequencies of ADNR with different crystal structures are given. The calculations demonstrate that the ADNR effect can be generated at the normalized frequency from 0.8 to 1.05.
A three-dimensional parabolic equation model of sound propagation using higher-order operator splitting and Padé approximants132(2012); http://dx.doi.org/10.1121/1.4754421View Description Hide Description
An alternating direction implicit (ADI) three-dimensional fluid parabolic equationsolution method with enhanced accuracy is presented. The method uses a square-root Helmholtz operator splitting algorithm that retains cross-multiplied operator terms that have been previously neglected. With these higher-order cross terms, the valid angular range of the parabolic equationsolution is improved. The method is tested for accuracy against an image solution in an idealized wedge problem. Computational efficiency improvements resulting from the ADI discretization are also discussed.
132(2012); http://dx.doi.org/10.1121/1.4757698View Description Hide Description
The study investigated the perception of speech produced to counter the effects of adverse listening conditions. Participants completed a problem-solving task with an interlocutor in good listening conditions (NB) or with the interlocutor hearing them via a vocoder (VOC) or babble (BAB). Keywords extracted from recordings were presented in babble for initial consonant identification. BAB tokens were identified faster than VOC or NB tokens even though VOC and BAB tokens were rated as similarly clear. Acoustic measures showed clarifications to be global rather than specifically enhancing phonological contrasts. These results suggest that clear speaking styles are tailored to listeners' needs.
132(2012); http://dx.doi.org/10.1121/1.4757729View Description Hide Description
This study investigated the contribution of low-frequency harmonics to identifying Mandarin tones in natural and vocoded speech in quiet and noisy conditions. Results showed that low-frequency harmonics of natural speech led to highly accurate tone identification; however, for vocoded speech, low-frequency harmonics yielded lower tone identification than stimuli with full harmonics, except for tone 4. Analysis of the correlation between tone accuracy and the amplitude-F0 correlation index suggested that “more” speech contents (i.e., more harmonics) did not necessarily yield better tone recognition for vocoded speech, especially when the amplitude contour of the signals did not co-vary with the F0 contour.
Selective attention in an overcrowded auditory scene: Implications for auditory-based brain-computer interface design132(2012); http://dx.doi.org/10.1121/1.4757696View Description Hide Description
Listeners are good at attending to one auditory stream in a crowded environment. However, is there an upper limit of streams present in an auditory scene at which this selective attention breaks down? Here, participants were asked to attend one stream of spoken letters amidst other letter streams. In half of the trials, an initial primer was played, cueing subjects to the sound configuration. Results indicate that performance increases with token repetitions. Priming provided a performance benefit, suggesting that stream selection, not formation, is the bottleneck associated with attention in an overcrowded scene. Results' implications for brain-computer interfaces are discussed.
English sentence recognition in speech-shaped noise and multi-talker babble for English-, Chinese-, and Korean-native listeners132(2012); http://dx.doi.org/10.1121/1.4757730View Description Hide Description
This study aimed to investigate English sentence recognition in quiet and two types of maskers, multi-talker babble (MTB) and long-term speech-shaped noise (LTSSN), with varied signal-to-noise ratios, for English-, Chinese-, and Korean-native listeners. Results showed that first, sentence recognition for non-native listeners was affected more by background noise than that for native listeners; second, the masking effects of LTSSN were similar between Chinese and Korean listeners, but the masking effects of MTB were greater for Chinese than for Korean listeners, suggesting possible interaction effects between the non-native listener's native language and speech-like competing noise in sentence recognition.
132(2012); http://dx.doi.org/10.1121/1.4757697View Description Hide Description
To study the role of harmonic structure in pitch perception, normal-hearing listeners were tested using noise-vocoded harmonic tone complexes. When tested in a magnitude judgment procedure using vocoded versions generated with 2–128 channels, judgments of pitch strength increased systematically as the number of channels increased and reflected acoustic cues based on harmonic peak-to-valley ratio, but not cues based on periodicity strength. When tested in a fundamental frequency discrimination task, listeners correctly recognized the direction of pitch change with as few as eight noise-vocoded channels. The results suggest that spectral processing contributes substantially to pitch perception in normal-hearing listeners.
132(2012); http://dx.doi.org/10.1121/1.4758764View Description Hide Description
A proposed signal processing technique for incipient real time bearing fault detection based on kurtogram analysis is presented in this paper. The kurtogram is a fourth-order spectral analysis tool introduced for detecting and characterizing non-stationarities in a signal. This technique starts from investigating the resonance signatures over selected frequency bands to extract the representative features. The traditional spectral analysis is not appropriate for non-stationary vibration signal and for real time diagnosis. The performance of the proposed technique is examined by a series of experimental tests corresponding to different bearing conditions. Test results show that this signal processing technique is an effective bearing fault automatic detection method and gives a good basis for an integrated induction machine condition monitor.
132(2012); http://dx.doi.org/10.1121/1.4758985View Description Hide Description
A bandgap cannot be enlarged sufficiently enough to suppress a broad-band noise only with a single type of finite-length phononic crystals. Here, a hybrid phononic crystal consisting of a bi-prism and an inverted bi-prism is proposed for noise control in a broad band; a stop band is formed in a central frequency range while positive-positive and positive-negative refractions occur in lower and higher frequency ranges to concentrate acoustic energy in a central localized zone. Thereby, the remaining zone becomes little affected by the noise. Analysis and numerical simulations are given for the justification of the proposed configuration.
Vocalization of echolocation-like pulses for interindividual interaction in horseshoe bats (Rhinolophus ferrumequinum)132(2012); http://dx.doi.org/10.1121/1.4757695View Description Hide Description
Although much is known about the echolocation of horseshoe bats (Rhinolophus spp.), little is known about the characteristics and function of their communication calls. This study focused on a stereotyped behavior of a bat approaching a companion animal in the colony, and examined their interaction and vocalization during this behavior. The bats emit echolocation-like vocalizations when approaching each other and these vocalizations contain a “buildup” pulse sequence, in which the frequency of the pulse increases gradually to normal echolocation pulse frequencies. The results suggest that the echolocation-like pulses serve an important role in communication within the colony.
132(2012); http://dx.doi.org/10.1121/1.4758779View Description Hide Description
Including ocean noise in marine spatial planning requires predictions of noise levels on large spatiotemporal scales. Based on a simple sound transmission model and ship track data (Automatic Identification System, AIS), cumulative underwater acoustic energy from shipping was mapped throughout 2008 in the west Canadian Exclusive Economic Zone, showing high noise levels in critical habitats for endangered resident killer whales, exceeding limits of “good conservation status” under the EU Marine Strategy Framework Directive. Error analysis proved that rough calculations of noise occurrence and propagation can form a basis for management processes, because spending resources on unnecessary detail is wasteful and delays remedial action.
132(2012); http://dx.doi.org/10.1121/1.4758770View Description Hide Description
In cochlear implants (CIs), melodicpitch perception is limited by the spectral resolution, which in turn is limited by the number of spectral channels as well as interactions between adjacent channels. This study investigated the effect of channel interaction on melodic contour identification (MCI) in normal-hearing subjects listening to novel 16-channel sinewave vocoders that simulated channel interaction in CIsignal processing. MCI performance worsened as the degree of channel interaction increased. Although greater numbers of spectral channels may be beneficial to melodicpitch perception, the present data suggest that it is also important to improve independence among spectral channels.
132(2012); http://dx.doi.org/10.1121/1.4758826View Description Hide Description
Frequency domain linear prediction (FDLP) is a technique for auto-regressive modeling of Hilbert envelopes. In this letter, the resolution properties of the FDLP model are investigated using synthetic signals with impulses immersed in noise. The effect of various factors are studied which affect the temporal resolution and this analysis suggests ways to improve the resolution of the FDLP envelopes in noisy speech. The high resolution FDLP envelopes are used to derive robust features for phoneme recognition in noisy and reverberant speech. In these experiments, the FDLP features derived from high resolution envelopes provide significant improvements.
- LETTERS TO THE EDITOR
132(2012); http://dx.doi.org/10.1121/1.4757643View Description Hide Description
Structured soundsequences produced by humpback whales are described in the literature as hierarchically organized songs. Despite the prevalence of such descriptions, there is no direct evidence that humpback songs are hierarchically structured. It is suggested here that songs may instead be heterarchically structured, in which case traditional approaches to analyzingsongs may obscure their organizational and acoustical features. An alternative framework for characterizing patterns within songs is presented, derived from models of humpback whale sound production, that characterizes rhythmic and sequential regularities in the soundsequences produced by singing whales in terms of interacting cycles of breathing and internal air recirculation.
132(2012); http://dx.doi.org/10.1121/1.4756923View Description Hide Description
Sound absorption by openings has been rarely considered in room acoustics. In fact, information about small openings (such as ventilation grids) may sometimes be found, but nothing is said about larger openings, possibly as a consequence of the less likely occurrence in a design. In order to fill this gap, measurements were carried out in scale models,measuring the equivalent absorption due to different openings and comparing it with theoretical results. A “practical” model, showing a simple dependence on the opening dimension, was finally obtained and subsequently validated by measurements in a real room.
Humpback whale (Megaptera novaeangliae) singers in Hawaii are attracted to playback of similar song (L)132(2012); http://dx.doi.org/10.1121/1.4757739View Description Hide Description
The use of playback experiments to study humpback whale song was assessed. Singers clearly detected playback song while singing and with other singers in the distance. Singers approached or joined song similar to their own from as far as 800 m but did not do so for a different (foreign) song. In one compound trial, on the playback of different song, the singer moved away and continued singing; when the playback was changed to similar song, it stopped singing and joined the playback speaker. Song playback experiments on the breeding grounds are viable and may provide insight into song function.
132(2012); http://dx.doi.org/10.1121/1.4757750View Description Hide Description
Detection thresholds were measured for interaural time differences(ITDs) and interaural level differences (ILDs) that were carried by probe segments embedded in otherwise diotic broadband noise (fringe). The duration of the probe was varied between 5 and 200 ms, and the duration of the fringe was between 5 and 100 ms. Consistent with results of Akeroyd and Bernstein [(2001). J. Acoust. Soc. Am. 110, 2516–2526], it was found that a 5-ms fringe placed before a 5-ms probe (forward fringe) led to a larger threshold elevation than a 5-ms fringe placed after the probe (backward fringe). As suggested by Akeroyd and Bernstein, this effect was accounted for by a model providing an onset emphasis of a factor of 2. In contrast, for longer probe and fringe durations, which have not been tested before, a backward fringe had a stronger effect than a forward fringe. This surprising effect was accounted for by an extended model that provided an offset emphasis of a factor of 11 for a 50-ms probe and a 100-ms fringe.
- GENERAL LINEAR ACOUSTICS 
132(2012); http://dx.doi.org/10.1121/1.4757971View Description Hide Description
In this paper the recently developed, bi-velocity model of fluid mechanics based on the principles of linear irreversible thermodynamics (LIT) is applied to sound propagation in gases taking account of first-order thermal and viscous dissipation effects. The results are compared and contrasted with the classical Navier–Stokes–Fourier results of Pierce for this same situation cited in his textbook. Comparisons are also made with the recent analyses of Dadzie and Reese, whose molecularly based sound propagation calculations furnish results virtually identical with the purely macroscopic LIT-based bi-velocity results below, as well as being well-supported by experimental data. Illustrative dissipative sound propagation examples involving application of the bi-velocity model to several elementary situations are also provided, showing the disjoint entropy mode and the additional, evanescent viscous mode.
132(2012); http://dx.doi.org/10.1121/1.4756949View Description Hide Description
A one-dimensional problem of propagation of plane harmonic wave in macroscopically inhomogeneous materials is analyzed. A general description is proposed for the material of the equivalent fluid type characterized locally by two acoustical parameters: the wavenumber and the acoustical impedance. The coupled system of ordinary differential equations for amplitudes of forward and backward waves is derived. As an example the problem of wave interaction with a layer of inhomogeneous material placed between two homogeneous halfspaces is considered. The analytical solution and explicit expressions for reflection and transmission coefficients are obtained. It is shown that the presence of the inhomogeneous transition layer causes strong frequency dependence on both coefficients.