Volume 128, Issue 1, July 2010
- 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 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech production 
- speech perception 
- music and musical instruments 
- bioacoustics 
- acoustical news
- acoustical standards news
- advanced-degree dissertation abstracts
- reviews of acoustical patents
Index of content:
- JASA EXPRESS LETTERS
128(2010); http://dx.doi.org/10.1121/1.3436498View Description Hide Description
As previously suggested, attention may increase segregation via enhancement and suppression sensory mechanisms. To test this hypothesis, we proposed an interleaved melody paradigm with two rhythm conditions applied to familiar target melodies and unfamiliar distractor melodies sharing pitch and timbre properties. When rhythms of both target and distractor were irregular, target melodies were identified above chance level. A sensory enhancement mechanism guided by listeners’ knowledge may have helped to extract targets from the interleaved sequence. When the distractor was rhythmically regular, performance was increased, suggesting that the distractor may have been suppressed by a sensory suppression mechanism.
128(2010); http://dx.doi.org/10.1121/1.3425742View Description Hide Description
The Balinese gamelan gong ageng wadon produces distinct acoustic beating (called ombak) when struck. This phenomenon is explored using both acoustical and vibrometry measurements. The measurements have revealed the beating has two sources. First, there are four closely spaced modes that, given their asymmetric vibration patterns, might have been deliberately hammered into the response of the gong. Second, and more importantly, a nonlinear structural response of the gong causes the fundamental axisymmetric mode to produce harmonics. The second harmonic of the fundamental mode interacts with the second axisymmetric mode with relative amplitudes such that strong beating is produced.
128(2010); http://dx.doi.org/10.1121/1.3442725View Description Hide Description
Continuous volcanic infrasound signal was recorded on a three-microphone network at Kilauea in July 2008 and inverted for near-surface horizontal winds. Inter-station phase delays, determined by signal cross-correlation, vary by up to 4% and are attributable to variable atmospheric conditions. The results suggest two predominant weather regimes during the study period: (1) 6–9 m/s easterly trade winds and (2) lower-intensity 2–5 m/s mountain breezes from Mauna Loa. The results demonstrate the potential of using infrasound for tracking local averaged meteorological conditions, which has implications for modeling plume dispersal and quantifying gas flux.
128(2010); http://dx.doi.org/10.1121/1.3443568View Description Hide Description
A numerical thought experiment was conducted to assess whether stimulus-specific, short-term changes in auditory neural responsiveness could explain the formation of auditory objects underlying the auditory continuity illusion. A tonotopic, two-layer feedforward network model with one time constant for synaptic weight augmentation based on firing rate, and an independent time constant for synaptic weight decay was presented with classical continuity illusion stimuli. The results suggest that the continuity illusion could, in principle, be explained by basic, duration-dependent auditory circuit behavior, which could emerge at either early or later stages of processing.
The role of segmentation difficulties in speech-in-speech understanding in older and hearing-impaired adults128(2010); http://dx.doi.org/10.1121/1.3443570View Description Hide Description
Older people often complain of difficulties in understanding speech in noisy circumstances. The current study tested the hypothesis that problems segmenting speech may contribute to these difficulties. Segmentation ability was measured in young normal-hearing, older normal-hearing and older hearing-impaired listeners. Listeners were presented with sentences in competing speech and resultant misperceptions were analyzed in terms of their accordance with the metrical segmentation strategy. While strong support for this strategy was indicated, no difference in the use of this strategy was found across the three listener groups, suggesting older listeners were unlikely to be experiencing segmentation difficulties at the sub-lexical level.
128(2010); http://dx.doi.org/10.1121/1.3448022View Description Hide Description
This study examined whether listeners align to reduced speech. Participants were asked to shadow sentences from a casual speech corpus containing canonical and reduced targets. Participants’ productions showed alignment: durations of canonical targets were longer than durations of reduced targets; and participants often imitated the segment types (canonical versus reduced) in both targets. The effect sizes were similar to previous work on alignment. In addition, shadowed productions were overall longer in duration than the original stimuli and this effect was larger for reduced than canonical targets. A possible explanation for this finding is that listeners reconstruct canonical forms from reduced forms.
128(2010); http://dx.doi.org/10.1121/1.3448024View Description Hide Description
The aim of the present letter is to identify the contribution of a macroscopic source of elastic nonlinearity in concrete, a medium which by nature is nonlinear, and belongs to the nonlinear mesoscopic class of materials. The influence of real, localized macro-cracks is characterized with respect to the intrinsic nonlinearity of the material. The influence of the size of the source on the amplitude of the measured nonlinearity is qualitatively demonstrated. A comparison is made between the changes in linear and nonlinear parameters.
128(2010); http://dx.doi.org/10.1121/1.3431102View Description Hide Description
Southern French listeners were trained on the word final Standard French /e/-/ɛ/ contrast that does not exist in their dialect. They learned to associate minimal pairs of new words with visual shapes. Although final training session performance was relatively high, the learning did not transfer to a lexical decision task with phonological priming. Thus successful training on a phonemic contrast did not guarantee the efficient use of this contrast in spoken word recognition tasks. These findings are discussed in light of abstractionist and exemplarist models.
Differences in distortion product otoacoustic emission phase recorded from human neonates using two popular probes128(2010); http://dx.doi.org/10.1121/1.3453415View Description Hide Description
DPOAE phase was measured across a 3-octave frequency range from two groups of newborns using and ER10C probe microphones. A marked phase shift was noted in the mid-to-high frequency range for newborn data recorded with the ER10C only. In contrast, the ER10B+ produced phase that was approximately invariant as a function of frequency for most of the range. Probe-related phase shifts can be effectively eliminated by correcting for variations in the phases of the primary tones. Results highlight the importance of detecting and correcting for system-related phase shifts so they are not misinterpreted as cochlear in origin.
128(2010); http://dx.doi.org/10.1121/1.3453764View Description Hide Description
Two hallmark features of auditory neuropathy (AN) are normal outer hair cell function in the presence of an absent/abnormal auditory brainstem response (ABR). Studies of human AN patients are unable to determine whether disruption of the ABR is the result of a reduction of neural input, a loss of auditory nerve fiber (ANF) synchrony, or both. Neurophysiological data from the carboplatin model of AN reveal intact neural synchrony in the auditory nerve and inferior colliculus, despite significant reductions in neural input. These data suggest that (1), intact neural synchrony is available to support an ABR following carboplatin treatment and, (2), impaired spike timing intrinsic to neurons is required for the disruption of the ABR observed in human AN.
128(2010); http://dx.doi.org/10.1121/1.3453768View Description Hide Description
The waveguide invariant is typically defined using of normal modes or ray theory, but it can also be related to the wavenumber-integration method for calculating the acoustic field in a waveguide. In this letter, the Wiener–Khinchin Theorem is used to show that the autocorrelation of the wavenumber-integration kernel, when plotted versus wavenumber difference and frequency, contains striations that can be described by the waveguide invariant.
- LETTERS TO THE EDITOR
Response to “Comments on ‘On Dowell’s simplification for acoustic cavity-structure interaction and consistent alternatives [J. Acoust. Soc. Am.127, 22–32 (2010)]’ ”128(2010); http://dx.doi.org/10.1121/1.3436551View Description Hide Description
Dowell [J. Acoust. Soc. Am.128, 1–2 (2010)] commented on several aspects of an approximation commonly invoked to model the coupling of an acoustic cavity and a surrounding structure. Additional observations regarding these issues are provided herein, as well as an explanation of discrepancies in the low frequency pressure predicted by the approximation.
- NONLINEAR ACOUSTICS 
128(2010); http://dx.doi.org/10.1121/1.3436520View Description Hide Description
This paper numerically investigates the effect of mass transfer processes on spherical single bubble dynamics using the Hertz–Langmuir–Knudsen approximation for the mass flux across the interface.Bubble behavior, with and without mass transfer, is studied for different values of pressure wave amplitude and frequency, as well as initial bubble radius. Whereas mass transfer processes do not seem to play a significant role on the bubble response for pressure amplitudes smaller than 0.9 atm, they appear to have an important effect when the amplitude is greater than or equal to 1 atm. For the later case, where the minimum liquidpressure reaches values around its vapor pressure, the importance of mass transfer depends on frequency. For frequencies in the range and initial bubble radii of the order of tens of microns, bubble implosions with and with no mass transfer are significantly different; smaller radii display a lower sensitivity. In this regime, accurate model predictions must, therefore, carefully select the correct value of the accommodation coefficient. For frequencies greater than , as a first approximation mass transfer can be ignored.
Theoretical investigation of shear stress generated by a contrast microbubble on the cell membrane as a mechanism for sonoporation128(2010); http://dx.doi.org/10.1121/1.3419775View Description Hide Description
There are numerous experimental investigations on sonoporation, while the theoretical background of this phenomenon still is in its infancy. One of the suggested mechanisms of sonoporation is linked to shear stress exerted on the cell membrane by acoustic microstreaming generated by a contrast microbubble pulsating nearby a cell. Currently, the existing model of this effect is based on an equation that has been derived for a free hemispherical bubble resting on a rigid plane. Such a model is not adequate for a contrast microbubble. In this paper, an improved theory is suggested that assumes an encapsulated bubble to be detached from the cell membrane. The improved model allows one to calculate the shear stress distribution on the cell membrane at different values of the acoustic parameters. The second problem considered is how to apply the model for pairwise bubble-cell interactions to bubble-cell solutions, which one has to deal with in experiments. An approach is proposed to evaluate the number of sonoporated cells in a bubble-cell solution. It is shown that the reaction of a bubble-cell solution to the variation of the acoustic parameters can be different from what is predicted by the analysis of interactions between single bubbles and cells.
- AEROACOUSTICS, ATMOSPHERIC SOUND 
128(2010); http://dx.doi.org/10.1121/1.3397453View Description Hide Description
The diffuse field assumption employed in basic statistical energy analysis (SEA) and in statistical room acoustics is violated for source and receiver positions close to boundaries or discontinuities. A simple approach is proposed to include the correction initially suggested by Waterhouse based on spherical Bessel functions in SEA predictions for rectangular rooms. With this modification the SEA results will be augmented by a position dependence and an additional frequency dependence. The approach is applied and demonstrated also for plate-like structures with different boundary conditions. An analytical solution is shown for the corner position on a simply supported plate and for edge positions on plates with more complex boundary conditions. The validity of the approach is confirmed by means of comparisons with modal analysis and finite element calculations.
- UNDERWATER SOUND 
128(2010); http://dx.doi.org/10.1121/1.3397394View Description Hide Description
Reverberation is commonly calculated by estimating the propagation loss to and from an elementary area, defined by transmitted pulse length and beam width, and treating the resulting backscatter from the area as a function of its range. In reality reverberation is strictly a function of time and contributions for a given time come from many ranges. Closed-form solutions are given for reverberation calculated both at fixed range and at fixed time isovelocity water and some variants of Lambert’s law and linear reflection loss with an abrupt critical angle. These are derived by considering the shape of the two-way scattered multipath pulse envelope from a point scatterer. The ratio of these two solutions is shown to depend on the dominant propagation angle spread for the particular range or time. The ratio is largest at intermediate ranges (though typically less than 1 dB) and depends explicitly on the critical angle. At longer ranges mode-stripping reduces the propagation angle spread and the ratio reduces ultimately to unity. At short range the ratio is also close to unity although interpreting it requires care.
128(2010); http://dx.doi.org/10.1121/1.3445783View Description Hide Description
This paper introduces a conformal transform of an acoustic domain under a one-dimensional, rough sea surface onto a domain with a flat top. This non-perturbative transform can include many hundreds of wavelengths of the surface variation. The resulting two-dimensional, flat-topped domain allows direct application of any existing, acoustic propagationmodel of the Helmholtz or wave equation using transformed sound speeds. Such a transform-model combination applies where the surface particle velocity is much slower than sound speed, such that the boundary motion can be neglected. Once the acoustic field is computed, the bijective (one-to-one and onto) mapping permits the field interpolation in terms of the original coordinates. The Bergström method for inverse Riemann maps determines the transform by iterated solution of an integral equation for a surface matching term. Rough sea surface forward scatter test cases provide verification of the method using a particular parabolic equationmodel of the Helmholtz equation.
An approximate form of the Rayleigh reflection loss and its phase: Application to reverberation calculation128(2010); http://dx.doi.org/10.1121/1.3372731View Description Hide Description
A useful approximation to the Rayleigh reflection coefficient for two half-spaces composed of water over sediment is derived. This exhibits dependence on angle that may deviate considerably from linear in the interval between grazing and critical. It shows that the non-linearity can be expressed as a separate function that multiplies the linear loss coefficient. This non-linearity term depends only on sediment density and does not depend on sediment sound speed or volume absorption. The non-linearity term tends to unity, i.e., the reflection loss becomes effectively linear, when the density ratio is about 1.27. The reflection phase in the same approximation leads to the well-known “effective depth” and “lateral shift.” A class of closed-form reverberation (and signal-to-reverberation) expressions has already been developed [C. H. Harrison, J. Acoust. Soc. Am.114, 2744–2756 (Year: 2003); C. H. Harrison, J. Comput. Acoust.13, 317–340 (Year: 2005); C. H. Harrison, IEEE J. Ocean. Eng.30, 660–675 (Year: 2005)]. The findings of this paper enable one to convert these reverberation expressions from simple linear loss to more general reflecting environments. Correction curves are calculated in terms of sediment density. These curves are applied to a test case taken from a recent ONR-funded Reverberation Workshop.
A sound budget for the southeastern Bering Sea: Measuring wind, rainfall, shipping, and other sources of underwater sound128(2010); http://dx.doi.org/10.1121/1.3436547View Description Hide Description
Ambient sound in the ocean contains quantifiable information about the marine environment. A passive aquatic listener (PAL) was deployed at a long-term mooring site in the southeastern Bering Sea from 27 April through 28 September 2004. This was a chain mooring with lots of clanking. However, the sampling strategy of the PAL filtered through this noise and allowed the background sound field to be quantified for natural signals. Distinctive signals include the sound from wind, drizzle and rain. These sources dominate the sound budget and their intensity can be used to quantify wind speed and rainfall rate. The wind speed measurement has an accuracy of when compared to a buoy-mounted anemometer. The rainfall rate measurement is consistent with a land-based measurement in the Aleutian chain at Cold Bay, AK (170 km south of the mooring location). Other identifiable sounds include ships and short transient tones. The PAL was designed to reject transients in the range important for quantification of wind speed and rainfall, but serendipitously recorded peaks in the sound spectrum between 200 Hz and 3 kHz. Some of these tones are consistent with whale calls, but most are apparently associated with mooring self-noise.