Volume 125, Issue 1, January 2009
- jasa express letters
- letters to the editor
- general linear acoustics 
- underwater sound 
- 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—usa
- acoustical standards news
- book reviews
- reviews of acoustical patents
Index of content:
- JASA EXPRESS LETTERS
125(2009); http://dx.doi.org/10.1121/1.3040021View Description Hide Description
Impedance measurements with a magneto-elastic active sensor are explored for inferring the magneto-mechanical impedance (MMI) of a metallic structure. It is shown that the MMI contains electrical response of the sensor and both electrical and mechanical structural responses. An analytical model is suggested that accounts for electrical characteristics of the sensor, sensor/structure electromagnetic interaction, and multimodal structural dynamic behavior. The model is validated with a set of MMI experiments demonstrating feasibility of deducing structural natural frequencies and structural vibration modes.
125(2009); http://dx.doi.org/10.1121/1.3040022View Description Hide Description
In this letter, a new feature extraction technique based on modulation spectrum derived from syllable-length segments of subband temporal envelopes is proposed. These subband envelopes are derived from autoregressive modeling of Hilbert envelopes of the signal in critical bands, processed by both a static (logarithmic) and a dynamic (adaptive loops) compression. These features are then used for machine recognition of phonemes in telephonespeech. Without degrading the performance in clean conditions, the proposed features show significant improvements compared to other state-of-the-art speech analysis techniques. In addition to the overall phoneme recognition rates, the performance with broad phonetic classes is reported.
125(2009); http://dx.doi.org/10.1121/1.3040024View Description Hide Description
The effects of time-reversed room acoustics on word recognition abilities were examined using virtual auditory space techniques, which allowed for temporal manipulation of the room acoustics independent of the speech source signals. Two acoustical conditions were tested: one in which room acoustics were simulated in a realistic time-forward fashion and one in which the room acoustics were reversed in time, causing reverberation and acoustic reflections to precede the direct-path energy. Significant decreases in speech intelligibility—from 89% on average to less than 25%—were observed between the time-forward and time-reversed rooms. This result is not predictable using standard methods for estimating speech intelligibility based on the modulation transfer function of the room. It may instead be due to increased degradation of onset information in the speech signals when room acoustics are time-reversed.
125(2009); http://dx.doi.org/10.1121/1.3040027View Description Hide Description
The detectability of a tone added to a masker is superior when the detection trial is preceded by the masker than the signal-plus-masker. This auditory enhancement can withstand long temporal gaps between the precursor and the trial, suggesting that for yes/no trials sensitivity may depend on the stimulus presented in the prior trial. The results from an experiment examining the detectability of a tone added to 6-tone maskers confirmed sequential effects on sensitivity. The values of were higher when the prior trial was a no-signal (masker alone) trial compared to a signal (signal-plus-masker) trial.
125(2009); http://dx.doi.org/10.1121/1.3040028View Description Hide Description
This study investigated the effects of anthropogenic sound exposure on the vocal behavior of free-ranging killer whales. Endangered Southern Resident killer whales inhabit areas including the urban coastal waters of Puget Sound near Seattle, WA, where anthropogenic sounds are ubiquitous, particularly those from motorized vessels. A calibrated recording system was used to measure killer whale call source levels and background noise levels . Results show that whales increased their call amplitude by for every increase in background noise levels. Furthermore, nearby vessel counts were positively correlated with these observed background noise levels.
125(2009); http://dx.doi.org/10.1121/1.3040031View Description Hide Description
Modulation detection thresholds of a sinusoidally amplitude-modulated tone were measured for two different positions of the low-level carrier relative to the fine structure of the threshold in quiet. Modulation detection thresholds were higher for a carrier at a fine-structure minimum than for a carrier at a fine-structure maximum, regardless of whether the carriers had the same sound pressure level or the same sensation level. This indicates that even for small variations of the carrier frequency, the sensitivity to amplitude modulation can vary substantially due to the frequency characteristics of the threshold in quiet.
Monitoring progressive damage in polymer-based composite using nonlinear dynamics and acoustic emission125(2009); http://dx.doi.org/10.1121/1.2993755View Description Hide Description
In this work quantitative results of applying nonlinear acoustic dynamics to study progressive damage in a polymer-based composite SMC (sheet molding compound) are presented. Via carefully controlled resonant plate experiment, nonlinear slow dynamics (SNLD) response of SMC in terms of relaxation time and frequency shift has been shown to be very sensitive to gradual damage induced using three-point bending tests. Besides, acoustic emission monitoring is used to characterize damage through the elastic energy released by SMC at every damage step. Interesting logarithmlike changes of the SNLD parameters as a function of the acoustic emission cumulated energy are found.
125(2009); http://dx.doi.org/10.1121/1.2965550View Description Hide Description
Measurements of temporal and spatial coherence are most always confounded by the presence of multipath interference. Here, two sets of data are presented that allow separation of arrivals from individual propagating modes and then unambiguous computations of temporal and spatial coherence free of multipath effects. A consistent finding for surface reflected bottom reflected (SRBR) modes is that lower order mode are more coherent in both time and space than higher order (steeper) modes. Also, SRBR paths are much more coherent than refracted bottom reflected mode groups that cannot be separated in time and are affected by multi-mode interference.
- LETTERS TO THE EDITOR
125(2009); http://dx.doi.org/10.1121/1.3035901View Description Hide Description
The solution to the problem of plane wave and point source scattering by two concentric fluid spheres is derived. The effect of differences in sound speed, density, and absorption coefficient is taken into account. The scattered field is then found in the limit as the outer sphere becomes an infinitely thin shell and compared to the solution for a single fluid sphere for verification. A simulation is then performed using the concentric fluid sphere solution as an approximation to the human head and compared to the solution of a single fluid sphere with the properties of either bone or water. The solutions were found to be similar outside of the spheres but differ significantly inside the spheres.
Toward the acoustical characterization of asphalt pavements: Analysis of the tire/road sound from a porous surface125(2009); http://dx.doi.org/10.1121/1.3025911View Description Hide Description
Sound level in close proximity to the contact patch of the tire and road is analyzed as a function of the vehicle speed in the acoustic frequency range, showing different behavior depending on frequency. At least two regions are observed; one at low frequencies, where the variation in sound with speed (coefficient ) increases with frequency, and the other at higher frequencies, where such sound/speed variation does not increase significantly with frequency. The dependence of at low frequencies seems to be correlated with the high sound absorption of this porous surface.
125(2009); http://dx.doi.org/10.1121/1.3035830View Description Hide Description
A recent paper [Higley et al. , J. Acoust. Soc. Am.118, 2365–2372 (Year: 2005)] investigated synthetic aperture communications in shallow water exploiting the relative motion between a source and a receiver. This letter presents a feasibility study of synthetic aperture communications at global distances using the acoustic data from the Heard Island Feasibility Test conducted in January 1991 [Baggeroer and Munk, Phys. Today45, 22–30 (Year: 1992)]. Specifically, a reception at Ascension Island, about from the source ship moving at about near Heard Island, is analyzed by treating the 255-digit -sequence tomography signal as a binary-phase shift-keying communication signal with an information rate of . The performance using a single receiver combining three consecutive receptions spaced apart indicates that synthetic aperture acoustic communications is feasible at global distances.
125(2009); http://dx.doi.org/10.1121/1.2950090View Description Hide Description
Recently, a paper by Lakashkin et al. (2007) (“Power amplification in the mammalian cochlea,” Curr. Biol.17, 1340–1344) was published on how power can be measured in the mammalian cochlea. The general subject is of current widespread interest, so the question of whether the method used by Lakashkin et al. is valid may be of interest to the readers of this journal. Power generation in the cochlea can account for the extraordinary sensitivity of hearing. Lukashkin et al. claimed to provide a direct proof of cochlear power generation. A first-order spring-dashpot system was used to model the organ of Corti. The power flux direction can be derived from the sign of the phase difference between the force and displacement, which can be presented as a “hysteresis plot.” Basilar membrane (BM) vibration near the characteristic frequency (CF) was measured while applying a low-frequency modulation tone together with the CF tone. A force was derived from the modulation profile of the BM CF vibration and when plotted versus the displacement at the modulation frequency, the function had a counterclockwise direction of hysteresis, suggesting power generation. In this letter, we present comments on the analysis in the report: (1) that it is not appropriate to analyze at the modulation frequency to derive the power generation at CF; (2) that the derivation of a force from just the displacement profile is not justified, followed by an alternative interpretation of the experimental data.
Reduced contribution of a nonsimultaneous mistuned harmonic to residue pitch: The role of harmonic number125(2009); http://dx.doi.org/10.1121/1.3026327View Description Hide Description
Listeners adjusted a matching sound so that its pitch equaled that of a subsequent complex tone (12 harmonics of a ), whose mistuned harmonic was presented either simultaneously with or after the other harmonics. The third or the fourth harmonic was mistuned. For both harmonics, pitch shifts were significantly smaller when the mistuned harmonic was presented after rather than simultaneously with the remainder of the target complex and when the component corresponding to the mistuned harmonic was absent (as opposed to present) from the matching sound. Presenting the mistuned component after the remainder of the complex generally reduced the pitch shifts more for the third than for the fourth harmonic; the nonsimultaneous presentation reduced shifts by a factor of 2.8 (third) and 1.7 (fourth) in the presence, and 6.4 (third) and 1.9 (fourth) in the absence of the nominally mistuned harmonic from the matching sound. The results are discussed in terms of an analytical listening and matching strategy that results in larger pitch shifts for a nonsimultaneous mistuned harmonic that has an octave or double-octave relationship to the than for one that does not, without it necessarily being temporally integrated into the residue pitch of the complex.
125(2009); http://dx.doi.org/10.1121/1.3033740View Description Hide Description
The purpose of this study was to determine the degree to which synthetic vowel samples based on previously reported vocal tract area functions of eight speakers could be accurately identified by listeners. Vowels were synthesized with a wave-reflection type of vocal tract model coupled to a voice source. A particular vowel was generated by specifying an area function that had been derived from previous magnetic resonance imaging based measurements. The vowel samples were presented to ten listeners in a forced choice paradigm in which they were asked to identify the vowel. Results indicated that the vowels [i], [æ], and [u] were identified most accurately for all of speakers. The identification errors of the other vowels were typically due to confusions with adjacent vowels.
125(2009); http://dx.doi.org/10.1121/1.3025915View Description Hide Description
Many of the items in the “Speech, Spatial, and Qualities of Hearing” scale questionnaire [S. Gatehouse and W. Noble, Int. J. Audiol.43, 85–99 (2004)] are concerned with speech understanding in a variety of backgrounds, both speech and nonspeech. To study if this self-report data reflected informational masking, previously collected data on 414 people were analyzed. The lowest scores (greatest difficulties) were found for the two items in which there were two speech targets, with successively higher scores for competing speech (six items), energetic masking (one item), and no masking (three items). The results suggest significant masking by competing speech in everyday listening situations.
Abnormal processing of temporal fine structure in speech for frequencies where absolute thresholds are normal125(2009); http://dx.doi.org/10.1121/1.2939125View Description Hide Description
The identification of nonsense syllables that were lowpass filtered at was compared for subjects with normal hearing and subjects with mild-to-severe hearing loss at high frequencies but with normal or near-normal hearing at low frequencies. Absolute thresholds were mostly within the normal range (hearing level) for both groups for frequencies below . Performance was assessed with intact speech,speech that had been processed to preserve only temporal envelope cues in a few frequency bands (E speech), and speech that had been processed to remove envelope cues as far as possible while preserving temporal fine structure cues, again in a few frequency bands (TFS speech). For the intact speech and E speech, the hearing-impaired subjects performed slightly more poorly than the normal-hearing subjects, but this effect was significant only for the intact speech. For the TFS speech, the hearing-impaired subjects performed significantly more poorly than the normal-hearing subjects, with 12 out of 16 of the former performing at chance. The results indicate that, for people with hearing loss at medium to high frequencies, the processing of the TFS of speech can be degraded for frequencies where absolute thresholds are within the normal range.
- GENERAL LINEAR ACOUSTICS 
Sound transmission loss of rectangular and slit-shaped apertures: Experimental results and correlation with a modal model125(2009); http://dx.doi.org/10.1121/1.3003084View Description Hide Description
Among noise control techniques, enclosures are widely used. It is known that enclosure acoustic efficiency is strongly influenced by the presence of openings or leaks. Modeling of diffuse field sound transmission loss (TL) of apertures and slits is therefore critical when the enclosure acoustic performance characteristics need to be predicted with confidence either for design or for modifying existing enclosures. Recently, a general model for diffuse field sound TL of rectangular and circular apertures has been developed and validated with respect to existing analytical or numerical models. This paper presents an experimental validation of this new model. The aim was to develop a simple, reliable tool for predicting enclosure insertion loss using statistical energy analysis. Twelve out of the 15 test configurations were found to be reliable and were compared with theoretical models, which in fact correlate closely (without adjustment) with the experimental work.
125(2009); http://dx.doi.org/10.1121/1.3035839View Description Hide Description
Some further refinements are described for the -matrix approach to acoustic scattering. From the structure of the matrices involved, one can infer the Rayleigh limit explicitly for objects having no density contrast. One finds , where the -matrix involves integrals of the regular spherical wave functions over the object’s surface. The index of refraction and loss factor can be chosen as desired, and energy balance and reciprocity requirements are found to be met. The derivation can be extended to obtain the Rayleigh expansion, effectively describing as a series in ascending powers of the ratio of object size to wavelength. In trial cases, the series converges throughout the Rayleigh region and somewhat beyond. Bodies of high aspect ratio are also considered, where difficulties arise due to precision loss during numerical integration. Loss ranges from 4 or 5 significant figures (2:1 spheroid) to 22 figures (40:1 spheroid) or more. A class of surfaces has been found for which this problem can be avoided, however, enabling one to treat a variety of body shapes up to aspect ratios of 100:1 with no difficulty.
- UNDERWATER SOUND 
125(2009); http://dx.doi.org/10.1121/1.3025903View Description Hide Description
A three-dimensional (3D) propagation and scatteringmodel is developed for an offset acoustic source in an ocean with axisymmetric bathymetry. Based on the same theoretical foundation as the formulation presented by Taroudakis [M. I. Taroudakis, “A coupled-mode formulation for the solution in the presence of a conical sea-mount,” J. Comput. Acoust.4, 101–121 (1996)], the present approach combines a spectral decomposition in azimuth with a coupled-mode theory for two-way, range-dependent propagation. However, the earlier formulations were severely limited in terms of frequency, size, and geometry of the seamount, the seabed composition, and the distance between the source and the seamount, and were therefore severely limited in regard to realistic seamount problems. Without changing the fundamental theoretical foundation, the present approach applies a number of modifications to the numerical formulation, leading to orders of magnitude in numerical efficiency for realistic problems. Further, by using a standard normal modemodel for determining the fundamental modal solutions and coupling matrices, and by applying a simple superposition principle, the computational requirements are made independent of the distance between the seamount and the source and receivers, and dependent only on the geometry of the seamount and the source frequency. Therefore, realistic propagation and scattering scenarios can be modeled, including effects of seamount roughness and realistic sedimentary structure.