Volume 122, Issue 3, September 2007
- jasa express letters
- acoustical news—usa
- acoustical standards news
- reviews of acoustical patents
- letters to the editor
- general linear acoustics 
- 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 
Index of content:
- JASA EXPRESS LETTERS
122(2007); http://dx.doi.org/10.1121/1.2761883View Description Hide Description
Hearing thresholds for pure tones between 16 and were measured by an adaptive method. The maximum presentation level at the entrance of the outer ear was about SPL. To prevent the listeners from detecting subharmonic distortions in the lower frequencies, pink noise was presented as a masker. Even at , threshold values were obtained from 3 out of 32 ears. No thresholds were obtained for tone. Between 20 and , the threshold tended to increase rather gradually, whereas it increased abruptly between 16 and .
Reliability and frequency specificity of auditory steady-state response detected by phase spectral analysis122(2007); http://dx.doi.org/10.1121/1.2761888View Description Hide Description
Automatic threshold detection techniques are described for auditory steady-state response (ASSR) elicited with a sinusoidally amplitude-modulated tone. The reliability and frequency specificity of ASSR are discussed. When applied to awake adults and detected by phase spectral analysis, 40-Hz ASSR threshold patterns closely resemble their corresponding audiograms. However, 40-Hz ASSR is insufficiently reliable for determining hearing thresholds in young children during sleep. On the other hand, 80-Hz ASSR is detected clearly in sleeping children. Moreover, 80-Hz ASSR threshold patterns also closely resemble the corresponding audiograms. Therefore, 80-Hz ASSR appears to be useful for objective audiometry in children.
122(2007); http://dx.doi.org/10.1121/1.2761896View Description Hide Description
This study investigated effects of a previous sound presentation at the absolute threshold of hearing. Changes in threshold were measured when a pure tone at SPL preceded a test tone in the contra- or ipsilateral ear. When the previous and test sounds both had the same frequency of , threshold decreased approximately in the contralateral ear, and increased slightly in the ipsilateral ear. On the other hand, when the frequency of the previous sound differed from that of the test sound, the threshold was decreased slightly in the ipsilateral ear.
122(2007); http://dx.doi.org/10.1121/1.2761918View Description Hide Description
Leibold et al.[J. Acoust. Soc. Am.121, 2822–2831 (2007)] examined the perceptual weight subjects assigned to individual components of a multitone complex while performing a loudness-matching task. Weights agreed with the Moore et al.loudnessmodel[J. Audio Eng. Soc.45, 224–237 (1997)], except when components were widely spaced in frequency. In an effort to account for the data, the just-noticeable-difference (jnd) for intensity discrimination was measured for each component and compared to the weight for that component. The model predicts greater improvement in intensity discrimination with increasing bandwidth than was observed in the data. jnds were not correlated with weights in the widest frequency-spacing condition.
122(2007); http://dx.doi.org/10.1121/1.2761922View Description Hide Description
Induced loudness reduction (ILR) is a phenomenon by which a preceding higher-level tone (an inducer tone) reduces the loudness of a lower-level tone (a test tone). The strength of this effect depends on a number of parameters, reviewed here. Some of the implications of ILR on loudness data are presented via the analysis of several studies in which ILR likely resulted in otherwise unexplained biases in data sets. These results serve as examples of the pervasiveness of ILR in loudnessmeasurements and indicate that it is necessary to consider ILR when designing any psychoacousticalexperiment in which level varies.
122(2007); http://dx.doi.org/10.1121/1.2761924View Description Hide Description
This letter reanalyzes data from the literature in order to test two loudness-growth models for listeners with hearing losses of primarily cochlear origin: rapid growth and softness imperception. Five different studies using different methods to obtain individual loudness functions were used: absolute magnitude estimation, cross-modality matching with string length, categorical loudness scaling, loudness functions derived from binauralloudness summation, and loudness functions derived from spectral summation of loudness. Results from each of the methods show large individual differences. Individual loudness-growth functions encompass a wide range of shapes from rapid growth to softness imperception.
122(2007); http://dx.doi.org/10.1121/1.2761927View Description Hide Description
The perceptual relevance of adopting the temporal envelope to model the frequency band of (highband) in wideband speech signal is described in this letter. Based on theoretical work in psychoacoustics, we find out that the temporal envelope can indeed be a perceptual cue for the high-band signal, i.e., a noiseless sound can be obtained if the temporal envelope is roughly preserved. Subjective listening tests verify that transparent quality can be obtained if the model is used for the band. The proposed model has the benefits of offering flexible scalability and reducing the cost for quantization in coding applications.
- REVIEWS OF ACOUSTICAL PATENTS
122(2007); http://dx.doi.org/10.1121/1.2760212View Description Hide Description
The purpose of these acoustical patent reviews is to provide enough information for a Journal reader to decide whether to seek more information from the patent itself. Any opinions expressed here are those of the reviewers as individuals and are not legal opinions. Printed copies of United States Patents may be ordered at $3.00 each from the Commissioner of Patents and Trademarks, Washington, DC 20231. Patents are available via the Internet at http://www.uspto.gov.
- LETTERS TO THE EDITOR
A robust noniterative method for obtaining scattering strengths of multiply scattering point targets122(2007); http://dx.doi.org/10.1121/1.2764464View Description Hide Description
A noniterative method based on the least squares technique is presented in this letter to obtain the scattering strengths of multiply scattering point targets. Benefiting from the least squares’ optimization property, this new method achieves a good estimation of the scattering strengths. Compared with the noniterative method proposed in a recent paper [E. A. Marengo and F. K. Gruber “Noniterative analytical formula for inverse scattering of multiply scattering point targets,” J. Acoust. Soc. Am.120, 3782–3788 (2006)], the new method produces more accurate results in the presence of noise.
122(2007); http://dx.doi.org/10.1121/1.2756167View Description Hide Description
Intensity-discrimination thresholds were measured for a , pure tone for pedestal levels from 40 to sound pressure level (SPL) with and without a forward masker ( narrowband Gaussian noise,). When the masker was present, the masker and probe were separated by of silence. Unmasked and masked thresholds were measured in a two-interval monaural procedure and, separately, in a single-interval interaural procedure in which the pedestal and incremented pedestals were presented simultaneously to opposite ears. While the monaural thresholds were elevated markedly by the forward masker for mid-level pedestals, interaural thresholds were nearly unaffected by the masker across pedestal levels. The results argue against the notion that the monaural elevation in forward-masked thresholds is due to degraded encoding of intensity information at early stages of auditory processing.
122(2007); http://dx.doi.org/10.1121/1.2754063View Description Hide Description
Japanese infants at the ages of 6, 12, and were tested on their ability to discriminate three nonsense words with different phonotactic status: canonical keetsu, noncanonical but possible keets, and noncanonical and impossible keet. The results showed that 12 and olds discriminate the keets/keetsu pair, but infants in all age groups fail to discriminate the keets/keet pair. Taken together with the findings in our previous study [Kajikawa et al., J. Acoust. Soc. Am.120(4), 2278–2284 (2006)], these results suggest that Japanese infants develop the perceptual sensitivity for native phonotactics after of age, and that this sensitivity is limited to canonical patterns at this early developmental stage.
Effects of periodic interruptions on the intelligibility of speech based on temporal fine-structure or envelope cues122(2007); http://dx.doi.org/10.1121/1.2756161View Description Hide Description
The intelligibility of speech signals processed to retain either temporal envelope (E) or fine structure (TFS) cues within 16 0.4-oct-wide frequency bands was evaluated when processed stimuli were periodically interrupted at different rates. The interrupted E- and TFS-coded stimuli were highly intelligible in all conditions. However, the different patterns of results obtained for E- and TFS-coded speech suggest that the two types of stimuli do not convey identical speech cues. When an effect of interruption rate was observed, the effect occurred at low interruption rates and was stronger for E- than TFS-coded speech, suggesting larger involvement of modulation masking with E-coded speech.
- GENERAL LINEAR ACOUSTICS 
122(2007); http://dx.doi.org/10.1121/1.2747207View Description Hide Description
Multiple scattering of acoustic waves in a planar horizontal waveguide by finite-length cylinders is considered. Cylinder height equals the waveguide depth, and both are vertically constrained by the pressure-release boundaries. An analytically exact solution is obtained via normal mode expansion method in conjunction with the concept of the matrix. The problem is decomposed into an infinite number of two-dimensional multiple scattering problems, modulated by waveguide mode shapes. Examples are presented for an isovelocity waveguide in which the medium is uniform and the waveguide depth is constant. It is found that, in numerical computations, including one or two evanescent modes captures the essence of the evanescent modes. Multiple scattering in the waveguide is compared with the corresponding two-dimensional case. It is concluded that, in low frequencies, the wave patterns in the two cases are very similar, with a shift in the frequency. The similarity diminishes when there are multiple propagating modes. Despite the mode mixing, some key features in the scattering as observed in the two-dimensional problem remain observable in the waveguide case.
- NONLINEAR ACOUSTICS 
122(2007); http://dx.doi.org/10.1121/1.2767420View Description Hide Description
A three-dimensional model of the forward propagation of nonlinear sound beams in inhomogeneous media, a generalized Khokhlov-Zabolotskaya-Kuznetsov equation, is described. The Texas time-domain code (which accounts for paraxial diffraction, nonlinearity, thermoviscous absorption, and absorption and dispersion associated with multiple relaxation processes) was extended to solve for the propagation of nonlinear beams for the case where all medium properties vary in space. The code was validated with measurements of the nonlinear acoustic field generated by a phased array transducer operating at in water. A nonuniform layer of gel was employed to create an inhomogeneous medium. There was good agreement between the code and measurements in capturing the shift in the pressure distribution of both the fundamental and second harmonic due to the gel layer. The results indicate that the numerical tool described here is appropriate for propagation of nonlinear sound beams through weakly inhomogeneous media.
Nonlinear phenomena in the vocalizations of North Atlantic right whales (Eubalaena glacialis) and killer whales (Orcinus orca)122(2007); http://dx.doi.org/10.1121/1.2756263View Description Hide Description
Nonlinear phenomena or nonlinearities in animal vocalizations include features such as subharmonics, deterministic chaos, biphonation, and frequency jumps that until recently were generally ignored in acoustic analyses. Recent documentation of these phenomena in several species suggests that they may play a communicative role, though the exact function is still under investigation. Here, qualitative descriptions and quantitative analyses of nonlinearities in the vocalizations of killer whales (Orcinus orca) and North Atlantic right whales (Eubalaena glacialis) are provided. All four nonlinear features were present in both species, with at least one feature occurring in 92.4% of killer and 65.7% of right whale vocalizations analyzed. Occurrence of biphonation varied the most between species, being present in 89.0% of killer whale vocalizations and only 20.4% of right whale vocalizations. Because deterministic chaos is qualitatively and quantitatively different than random or Gaussian noise, a program designed specifically to identify deterministic chaos to confirm the presence of this nonlinearity was used. All segments tested in this software indicate that both species do indeed exhibit deterministic chaos. The results of this study provide confirmation that such features are common in the vocalizations of cetacean species and lay the groundwork for future studies.
- AEROACOUSTICS, ATMOSPHERIC SOUND 
Proper orthogonal decomposition and cluster weighted modeling for sensitivity analysis of sound propagation in the atmospheric surface layer122(2007); http://dx.doi.org/10.1121/1.2756176View Description Hide Description
Outdoor sound propagation predictions are compromised by uncertainty and error in the atmosphere and terrain representations, and sometimes also by simplified or incorrect physics. A model’s predictive power, i.e., its accurate representation of the sound propagation, cannot be assessed without first quantifying the ensemble sound pressure variability and sensitivity to uncertainties in the model’s governing parameters. This paper describes fundamental steps toward this goal for a single-frequency point source. The atmospheric surface layer is represented through Monin-Obukhov similarity theory and the acoustic ground properties with a relaxation model.Sound propagation is predicted with the parabolic equation method. Governing parameters are modeled as independent random variables across physically reasonable ranges. Latin hypercube sampling and proper orthogonal decomposition (POD) are employed in conjunction with cluster-weighted models to develop compact representations of the sound pressure random field. Full-field sensitivity of the sound pressure field is computed via the sensitivities of the POD mode coefficients to the system parameters. Ensemble statistics of the full-field sensitivities are computed to illustrate their relative importance at every down range location. The central role of sensitivity analysis in uncertainty quantification of outdoor sound propagation is discussed and pitfalls of sampling-based sensitivity analysis for outdoor sound propagation are described.
122(2007); http://dx.doi.org/10.1121/1.2764476View Description Hide Description
The determination of appropriate sound speed profiles in the modeling of near-ground propagation using a ray tracing method is investigated using a ray tracingmodel which is capable of performing axisymmetric calculations of the sound field around an isolated source. Eigenrays are traced using an iterative procedure which integrates the trajectory equations for each ray launched from the source at a specific direction. The calculation of sound energy losses is made by introducing appropriate coefficients to the equations representing the effect of ground and atmospheric absorption and the interaction with the atmospheric turbulence. The model is validated against analytical and numerical predictions of other methodologies for simple cases, as well as against measurements for nonrefractive atmospheric environments. A systematic investigation for near-ground propagation in downward and upward refractive atmosphere is made using experimental data. Guidelines for the suitable simulation of the wind velocity profile are derived by correlating predictions with measurements.