Volume 129, Issue 5, May 2011
- jasa express letters
- letters to the editor
- general linear 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 
- bioacoustics 
- acoustical news
- acoustical standards news
- book reviews
- reviews of acoustical patents
Index of content:
- JASA EXPRESS LETTERS
129(2011); http://dx.doi.org/10.1121/1.3567084View Description Hide Description
Concern about effects of anthropogenic noise on marine life has stimulated new studies to establish present-day oceannoise levels and compare them to noise levels from previous times. This paper reports on the trend in low-frequency (10–400 Hz) ambient noise levels and presents measurements made using a calibrated multi-element volume array at deep ocean sites in the Northeast Pacific from 1978 to 1986. The experiments provided spectral noise levels as well as horizontal and vertical noise directionality. The data presented here provide evidence that the trend derived from 1960s data extended to around 1980, but has since continued at a lower rate.
129(2011); http://dx.doi.org/10.1121/1.3565473View Description Hide Description
Inspired by the hearing organ of the fly Ormia ochracea, a miniature sound localization sensor is developed, which can be used to pinpoint a sound source in two dimensions described by the azimuth and elevation angles. The sensordevice employs an equilateral triangle configuration consisting of three mechanically coupled circular membranes whose oscillations are detected by a fiber-optic system. The experimental results indicate that significant amplification of the directional cues and directional sensitivity can be achieved with the fly-ear inspired sensor design. This work can provide a basis for the development of miniature sound localization sensors in two dimensions.
129(2011); http://dx.doi.org/10.1121/1.3554724View Description Hide Description
Scattering from a rough ocean bottom is described numerically with a two-way coupled-mode formalism that contains scattering effects to all orders and provides an exact solution to the wave equation. Both scattered field and direct blast components are computed within the formalism framework. A comparison of the scattered component solution from the coupled mode with the Born approximation (BA) solution for scattering from a rough bottom Pekeris waveguide shows that the BA predicts correctly the scattered field levels but not detailed structure. The transition from direct blast to scattered field dominance is identified in the total field time series.
129(2011); http://dx.doi.org/10.1121/1.3565474View Description Hide Description
In the frame of the fourth generation forum, France decided to develop sodium fast nuclear reactors. French Safety Authority requests the associated monitoring of argon gas into sodium. This implies to estimate the void fraction, and a histogram indicating the bubble population. In this context, the present letter studies the possibility of achieving an accurate determination of the histogram with acoustic methods. A nonlinear, two-frequency mixing technique has been implemented, and a specific optical device has been developed in order to validate the experimental results. The acoustically reconstructed histograms are in excellent agreement with those obtained using optical methods.
129(2011); http://dx.doi.org/10.1121/1.3565469View Description Hide Description
This paper is devoted to the study of acoustic vibrations induced by a flow upon an air-filled cylindrical tube vertically placed in water. A water pump with adapted piping generates a turbulent flow horizontally canalized in a large laboratory tank (6 m × 4 m × 3 m). The tube is located across this flow and an accelerometer measures vibrations. The signal processing performed on the recorded signals brings out resonance modes of the tube excited by the flow. A theoretical study (tube in air) and complementary experiments (tube in air and in water) are conducted to identify these modes.
129(2011); http://dx.doi.org/10.1121/1.3565471View Description Hide Description
The two-dimensional spectro-temporal modulation filtering concept of the auditory model [T. Chi, P. Ru, and S. A. Shamma, J. Acoust. Soc. Am. 118(2), 887–906 (2005)] is implemented on the Fourier spectrogram. The Fourier magnitude spectrogram is analyzed in terms of its joint spectro-temporal modulations, which embed the temporal dynamics and spectral structures. Instead of iterative projection methods, the overlap-and-add method is adopted to invert modified Fourier spectrograms back to sounds. The proposed framework not only provides a similar spectro-temporal analytical process for sounds as the auditory model but also produces synthesized sounds with better quality in a timely manner, which makes proposed framework feasible to human speech recognition (HSR) applications as well.
129(2011); http://dx.doi.org/10.1121/1.3567004View Description Hide Description
This letter focuses on the automatic estimation of the first subglottal resonance (Sg1). A database comprising speech and subglottal data of native American English speakers and bilingual Spanish/English speakers was used for the analysis. Data from 11 speakers (five males and six females) were used to derive an empirical relation among the first formant frequency, fundamental frequency, and Sg1. Using the derived relation, Sg1 was automatically estimated from voiced sounds in English and Spanish sentences spoken by 22 different speakers (11 males and 11 females). The error in estimating Sg1 was less than 50 Hz, on average.
129(2011); http://dx.doi.org/10.1121/1.3574501View Description Hide Description
The corruption of intonation contours has detrimental effects on sentence-based speech recognition in normal-hearing listeners Binns and Culling [(2007). J. Acoust. Soc. Am. 122, 1765–1776]. This paper examines whether this finding also applies to cochlear implant(CI) recipients. The subjects’ F0-discrimination and speech perception in the presence of noise were measured, using sentences with regular and inverted F0-contours. The results revealed that speech recognition for regular contours was significantly better than for inverted contours. This difference was related to the subjects’ F0-discrimination providing further evidence that the perception of intonation patterns is important for the CI-mediated speech recognition in noise.
129(2011); http://dx.doi.org/10.1121/1.3571534View Description Hide Description
The ability of listeners with bilateral sensorineural hearing loss to localize a speechsource in a multitalker mixture was measured. Five simultaneous words spoken by different talkers were presented over loudspeakers in a small room, and listeners localized one target word. Errors were significantly larger in this group compared to a control group with normal hearing. Localization of the target presented alone was not different between groups. The results suggest that hearing loss does not impair spatialhearingper se, but degrades the spatial representation of multiple simultaneous sounds.
- LETTERS TO THE EDITOR
Examining the use of a time-varying loudness algorithm for quantifying characteristics of nonlinearly propagated noise (L)129(2011); http://dx.doi.org/10.1121/1.3569710View Description Hide Description
A previous letter by Gee et al. [J. Acoust. Soc. Am. 121, EL1–EL7 (2007)] revealed likely shortcomings in using common, stationary (long-term) spectrum-based measures to quantify the perception of nonlinearly propagated noise. Here, the Glasberg and Moore [J. Audio Eng. Soc. 50, 331–342 (2002)] algorithm for time-varying loudness is investigated. Their short-term loudness, when applied to a shock-containing broadband signal and a phase-randomized signal with equivalent long-term spectrum, does not show a significant difference in loudness between the signals. Further analysis and discussion focus on the possible utility of the instantaneous loudness and the need for additional investigation in this area.
129(2011); http://dx.doi.org/10.1121/1.3559681View Description Hide Description
Quantitative elastography techniques have recently been developed to estimate the shear modulusμ of soft tissuesin vivo. In the case of isotropic and quasi-incompressible media, the Young’s modulusE is close to 3μ, which is not true in transverse anisotropictissues such as muscles. In this letter, the transverse isotropic model established for hexagonal crystals is revisited in the case of soft solids. Relationships between elastic constants and Young’s moduli are derived and validated on experimental data found in the literature. It is shown that and that E // cannot only be determined from the measurements of μ // and μ ⊥
129(2011); http://dx.doi.org/10.1121/1.3571424View Description Hide Description
Young deaf children using a cochlear implant develop speech abilities on the basis of speech temporal-envelope signals distributed over a limited number of frequency bands. A Headturn Preference Procedure was used to measure looking times in 6-month-old, normal-hearing infants during presentation of repeating or alternating sequences composed of different tokens of /aba/and /apa/ processed to retain envelope information below 64 Hz while degrading temporal fine structure cues. Infants attended longer to the alternating sequences, indicating that they perceive the voicing contrast on the basis of envelope cues alone in the absence of fine spectral and temporal structure information.
- GENERAL LINEAR ACOUSTICS 
The reciprocity theorem for the scattered field is the progenitor of the generalized optical theorem129(2011); http://dx.doi.org/10.1121/1.3569728View Description Hide Description
By analyzing correlation-type reciprocity theorems for wavefields in perturbed media, it is shown that the correlation-type reciprocity theorem for the scattered field is the progenitor of the generalized optical theorem. This reciprocity theorem, in contrast to the generalized optical theorem, allows for inhomogeneous background properties and does not make use of a far-field condition. This theorem specializes to the generalized optical theorem when considering a finite-size scatterer embedded in a homogeneous background medium and when utilizing the far-field condition. Moreover, it is shown that the reciprocity theorem for the scattered field is responsible for the cancellation of non-physical (spurious) arrivals in seismic interferometry, and as such provides the mathematical description of such arrivals. Even though here only acoustic waves are treated, the presented treatment is not limited to such wavefields and can be generalized to general wavefields. Therefore, this work provides the framework for deriving equivalents of the generalized optical theorem for general wavefields.
A characterization of the scattered acoustic intensity field in the resonance region for simple spheres129(2011); http://dx.doi.org/10.1121/1.3559689View Description Hide Description
The properties of the scattered acoustic vector fields generated by simple spheres illuminated by monotonic continuous wave (CW) plane waves are investigated. Analytical solutions are derived from general acoustic pressurescattering models and analyzed for wave numbers in the resonance region. Of particular interest is the understanding of the characteristics of the scattered acoustic vector field in the near-to-far-field transition region. The separable active and reactive components of the acoustic intensity are used to investigate the structural features of the scattered field components. Numerical results are presented for the near and transition regions for a rigid sphere. A method of mapping nulls in the scattered intensity field components is described. The analysis is then extended to include a simple fluid-filled boundary and finally the evacuated thin-walled shell. Near field acoustic intensity field structures are compared against mechanical material properties of vacuous shells. The ability to extract scattered field features is illustrated with measurements obtained from a recent in-air experiment using an anechoic chamber and acoustic vector sensor probes to measure the scattered acoustic vector field from rigid spheres.
Fast compressional wave attenuation and dispersion due to conversion scattering into slow shear waves in randomly heterogeneous porous media129(2011); http://dx.doi.org/10.1121/1.3560918View Description Hide Description
Within the viscosity-extended Biot framework of wave propagation in porous media, the existence of a slow shear wave mode with non-vanishing velocity is predicted. It is a highly diffusive shear mode wherein the two constituent phases essentially undergo out-of-phase shear motions (slow shear wave). In order to elucidate the interaction of this wave mode with propagating wave fields in an inhomogeneous medium the process of conversion scattering from fast compressional waves into slow shear waves is analyzed using the method of statistical smoothing in randomly heterogeneous poroelastic media. The result is a complex wave number of a coherent plane compressional wave propagating in a dynamic-equivalent homogeneous medium. Analysis of the results shows that the conversion scattering process draws energy from the propagating wave and therefore leads to attenuation and phase velocity dispersion. Attenuation and dispersion characteristics are typical for a relaxation process, in this case shear stress relaxation. The mechanism of conversion scattering into the slow shear wave is associated with the development of viscous boundary layers in the transition from the viscosity-dominated to inertial regime in a macroscopically homogeneous poroelastic solid.
129(2011); http://dx.doi.org/10.1121/1.3559685View Description Hide Description
The energyvelocity and Q factor of poroelastic acoustic waves in the context of classical isotropic Biot’s theory are revisited. Special attention is paid to the high frequency regime when interphase interaction is viscoelastic. The analogy with viscoelastic behavior is emphasized in derivation of the energy balance equations which relate kinetic energy, potential energy,viscous power dissipation, and elasticenergy stored associated with each wave. These lead to exact closed form expressions for the energyvelocity and Q factor for both longitudinal and shear waves from energy principles. Most notably, the analysis of the resulting expressions reveals that the energyvelocity of both longitudinal and shear waves equals (exceeds) the corresponding phase velocity in the case of the low (full) frequency range theory, and that the exact expression for the Q factor contains an additive correction due to viscoelastic interphase interaction.
- AEROACOUSTICS, ATMOSPHERIC SOUND 
129(2011); http://dx.doi.org/10.1121/1.3569740View Description Hide Description
Many models for the acoustical properties of rigid-porous media require knowledge of parameter values that are not available for outdoor ground surfaces. The relationship used between tortuosity and porosity for stacked spheres results in five characteristic impedance models that require not more than two adjustable parameters. These models and hard-backed-layer versions are considered further through numerical fitting of 42 short range level difference spectra measured over various ground surfaces. For all but eight sites, slit-pore, phenomenological and variable porosity models yield lower fitting errors than those given by the widely used one-parameter semi-empirical model. Data for 12 of 26 grassland sites and for three beech wood sites are fitted better by hard-backed-layer models. Parameter values obtained by fitting slit-pore and phenomenological models to data for relatively low flow resistivity grounds, such as forest floors, porous asphalt, and gravel, are consistent with values that have been obtained non-acoustically. Three impedance models yield reasonable fits to a narrow band excess attenuation spectrum measured at short range over railway ballast but, if extended reaction is taken into account, the hard-backed-layer version of the slit-pore model gives the most reasonable parameter values.
129(2011); http://dx.doi.org/10.1121/1.3569698View Description Hide Description
This paper presents experimental data concerning the flow and noise generated by a sharp-edged flat plate at low-to-moderate Reynolds number(Reynolds number based on chord of 2.0 × 105 to 5.0 × 105). The data are used to evaluate a variety of semi-empirical trailing edge noise prediction methods. All were found to under-predict noise at lower frequencies. Examination of the velocityspectra in the near wake reveals that there are energetic velocity fluctuations at low frequency about the trailing edge. A semi-empirical model of the surface pressurespectrum is derived for predicting the trailing edge noise at low-to-moderate Reynolds number.
129(2011); http://dx.doi.org/10.1121/1.3562567View Description Hide Description
The sound generated by a vortex propagating across a two-dimensional duct section with flexible walls (membranes) in an infinitely long rigid duct conveying a flow is investigated numerically using the matched asymptotic expansion technique and the potential theory. The effects of the initial vortex position, the mechanical properties of the flexible walls, and the mean flow on the sound generation are examined in detail. Results show that the presence of a vortex inside a uniform mean flow can strengthen or attenuate the sound generation, depending on the phase of the membrane vibration when the vortex starts vigorous interaction with the membranes and the strength of the mean flow. The results tend to imply that there is a higher chance of sound amplification when a vortex stream is moving closer to the lighter membrane under a relatively strong mean flow or when the mean flow is weak. The chances of sound amplification or attenuation are equal otherwise.
- UNDERWATER SOUND 
129(2011); http://dx.doi.org/10.1121/1.3557044View Description Hide Description
Measurements of marine surface winds are crucial to understanding mechanical and thermodynamic forces on the ocean. Satellite measurements of surface winds provide global coverage but are problematic at high wind speeds. Acoustic techniques of wind speed retrieval, and even for tracking hurricanes, have been suggested as an alternative since wind is a strong source of ambient noise in the ocean. Such approaches involve near-local measurements with bottom-mounted hydrophones located close to the area of interest. This paper suggests a complementary approach: measuring directivity of low-frequency ambient noise in the horizontal plane. These measurements would employ long vertical line arrays (VLAs) spanning a significant portion of the ocean waveguide. Two VLAs separated by a distance of some tens of kilometers and coherently measuring acoustic pressure form a single oceaninterferometer. By sampling the area of interest from different perspectives with at least two interferometers, marine surface winds might be mapped over horizontal scales of the order of 1000 km with about 10 km resolution (more specifically, the 10 km resolution here means that contribution from the basis functions representing surface wind field with the scale of spatial variations of the order of 10 km can be resolved; independent retrieval of the wind within 104 cells of a corresponding grid is hardly possible). An averaging time required to overcome statistical variability in the noise field is estimated to be about 3 h. Numerical simulations of propagation conditions typical for the North Atlantic Ocean are presented.