Volume 132, Issue 3, September 2012
- jasa express letters
- 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 
- acoustical standards news
- acoustical news
- book reviews
- reviews of acoustical patents
- program abstracts of the 164th meeting of the acoustical society of america
- award encomiums
- program abstracts of the 164th meeting of the acoustical society of america
Index of content:
- JASA EXPRESS LETTERS
132(2012); http://dx.doi.org/10.1121/1.4740225View Description Hide Description
Simultaneous long-term monitoring of underwater sound and ship traffic provided an opportunity to study how low-frequency noise correlated with ocean-based commercial shipping trends. Between 2007 and 2010 changes in regional shipping off southern California occurred as a consequence of economic and regulatory events. Underwater average noise levels measured before and during these events showed a net reduction of 12 dB. Statistical models revealed that a reduction of 1 ship transit per day resulted in 1 dB decrease in average noise. This synthesis of maritime traffic statistics with oceannoise monitoring provides an important step in understanding the magnitude and potential effects of chronic noise in marine habitats.
132(2012); http://dx.doi.org/10.1121/1.4740226View Description Hide Description
In 2009 two calibrated acoustic recorders were deployed in polar waters of the North Atlantic to study the seasonal occurrence of blue, fin, and sperm whales and to assess current ambient noise levels. Sounds from these cetaceans were recorded at both locations in most months of the year. During the summer months, seismic airguns associated with oil and gas exploration were audible for weeks at a time and dominated low frequency noise levels. Noise levels might further increase in the future as the receding sea ice enables extended human use of the area.
132(2012); http://dx.doi.org/10.1121/1.4740227View Description Hide Description
Following the derivation presented by Press and Ewing [Geophysics15, 426–446 (1950)], a normal modesolution for the Pekeris waveguide problem with an elastic bottom is outlined. The analytic solution is benchmarked against data collected in an experiment performed at the Naval Research Laboratory [Collis et al., J. Acoust. Soc. Am. 122, 1987–1993 (2007)]. Comparisons reveal a close match between the analytic solution and experimental data. Results are strongly dependent on the accuracy of the horizontal wavenumbers for the modes, and horizontal wavenumber spectra are compared against those from the experimental data.
132(2012); http://dx.doi.org/10.1121/1.4742318View Description Hide Description
Thresholds of formantdiscrimination of speech and non-speech sounds were compared for native listeners of English and Chinese. English listeners showed significantly better thresholds than Chinese listeners, not only for English vowels, but also for Chinese vowels. Thresholds for vowel-spectrum-shaped noise were comparable for the two groups. These results suggest that English listeners are more sensitive to formant frequency changes of vowel stimuli than Chinese listeners, possibly due to the denser vowel space for English than for Mandarin Chinese. However, the psychophysical capacity to discriminate formant frequency changes in non-speech sounds is similar for English and Chinese listeners.
132(2012); http://dx.doi.org/10.1121/1.4740462View Description Hide Description
Recent auditory brain stem response measurements in tinnitus subjects with normal audiograms indicate the presence of hidden hearing loss that manifests as reduced neural output from the cochlea at high sound intensities, and results from mice suggest a link to deafferentation of auditory nerve fibers. As deafferentation would lead to deficits in hearing performance, the present study investigates whether tinnitus patients with normal hearing thresholds show impairment in intensity discrimination compared to an audiometrically matched control group. Intensity discrimination thresholds were significantly increased in the tinnitus frequency range, consistent with the hypothesis that auditory nerve fiber deafferentation is associated with tinnitus.
132(2012); http://dx.doi.org/10.1121/1.4742138View Description Hide Description
Recently the concept of probing nonlinear elasticity at an interface prosthesis/bone has been proposed as a promising method to monitor the osseointegration/sealing of a prosthesis. However, the most suitable method to achieve this goal is a point of debate. To this purpose, two approaches termed the scaling subtraction method and the cross-correlation method are compared here. One nonlinear parameter derived from the cross-correlation method is as sensitive as a clinical device based on linear elasticity measurement. Further, this study shows that cross-correlation based methods are more sensitive than those based on subtraction/addition, such like pulse inversion and similar methods.
132(2012); http://dx.doi.org/10.1121/1.4742316View Description Hide Description
Previous research has found that the musical intervals found in speech are associated with various emotions. Intervals can be classified by their level of consonance or dissonance—how pleasant or unpleasant the combined tones sound to the ear. Exploratory investigations have indicated that in an agreeable conversation, the pitches of the last word in an utterance and the first word of a conversation partner’s utterance are consonantly related; in a disagreeable conversation, the two pitches are dissonantly related. The present results showed that the intervals between the tonics of the utterances in a conversation corresponded to the agreement between interlocutors.
132(2012); http://dx.doi.org/10.1121/1.4740518View Description Hide Description
Multireference partial field decomposition (PFD) can be used to generate coherent holograms for near-field acoustical holography measurements. PFD is most successful when the reference array completely senses all independent subsources, but meeting this requirement is not straightforward when the number of subsources and their locations are ambiguous (such as in aeroacoustic sources). A figure of merit based on spatial coherence lengths, called references per coherence length (RPL C ), is a useful metric to guide inter-reference spacing in the array design. For numerical, extended, arbitrarily coherent sources one reference per coherence length results in a sufficient reference array.
Slow and fast ultrasonic wave detection improvement in human trabecular bones using Golay code modulation132(2012); http://dx.doi.org/10.1121/1.4742729View Description Hide Description
The identification of fast and slow waves propagating through trabecular bone is a challenging task due to temporal wave overlap combined with the high attenuation of the fast wave in the presence of noise. However, it can provide valuable information about bone integrity and become a means for monitoring osteoporosis. The objective of this work is to apply different coded excitation methods for this purpose. The results for single-sine cycle pulse, Golay code, and chirp excitations are compared. It is shown that Golay code is superior to the other techniques due to its signal enhancement while exhibiting excellent resolution without the ambiguity of sidelobes.
132(2012); http://dx.doi.org/10.1121/1.4739251View Description Hide Description
To understand mysticete acoustic-based detection of ships, radiated noise from high-speed craft, cruise ships, catamarans and fishing vessels was recorded June–September 2009. Calibrated acoustic data (<2500 Hz) from a vertical hydrophone array was combined with ship passage information. A cruise ship had the highest broadband source level, while a fishing vessel had the lowest. Shipnoise radiated asymmetrically and varied with depth. Bow null-effect acoustic shadow zones were observed for all ship classes and were correlated with ship-length-to-draft-ratios. These shadow zones may reduce shipdetection by near-surface mysticetes.
132(2012); http://dx.doi.org/10.1121/1.4745839View Description Hide Description
The accuracy of a method [Wijnant et al., Proc. of ISMA 31, Leuven, Belgium (2010), Vol. 31] for measurement of the effective area-averaged in situsound absorption coefficient is investigated. Based on a local plane wave assumption, this method can be applied to sound fields for which a model is not available. Investigations were carried out by means of finite element simulations for a typical case. The results show that the method is a promising method for determining the effective area-averaged in situsound absorption coefficient in complex sound fields.
132(2012); http://dx.doi.org/10.1121/1.4746421View Description Hide Description
Extraction of Doppler signatures that characterize human motion has attracted a growing interest in recent years. These Doppler signatures are generated by various components of the human body while walking, and contain unique features that can be used for human detection and recognition. Although, a significant amount of research has been done in radio frequency regime for human Doppler signature extraction, considerably less has been done in acoustics. In this work, 40 kHz ultrasonicsonar is employed to measure the Doppler signature generated by the motion of body segments using different electronic and signal processing schemes. These schemes are based on both analog and digital demodulation with homodyne and heterodyne receiver circuitry. The results and analyses from these different schemes are presented.
132(2012); http://dx.doi.org/10.1121/1.4747826View Description Hide Description
The purpose of this study was to establish the potential utility of adaptive tracking procedures, relative to the method of constant stimuli, when examining consonant identification in cafeteria noise or four-talker babble. Thresholds for consonant identification were comparable for the two methods, while psychometric function slopes derived from the two methods were statistically different. To obtain accurate slope estimates from adaptive procedures, the target percent correct and change in variability with signal-to-noise ratio should be considered carefully. However, adaptive procedures are accurate and more efficient than the method of constant stimuli when the purpose is to estimate phoneme identification threshold.
- LETTERS TO THE EDITOR
Combining time of flight and diffraction tomography for high resolution breast imaging: Initial invivo results (L)132(2012); http://dx.doi.org/10.1121/1.4742697View Description Hide Description
Ultrasoundtomography (UST) is being developed to address the limitations of mammography in breast cancer detection. Central to the success of UST is the possibility of obtaining high-resolution images of tissue mechanical properties across the whole breast. A recent paper [Huthwaite and Simonetti, J. Acoust. Soc. Am. 130, 1721–1734 (2011)] made use of a numerical phantom to demonstrate that sufficient image resolution can be obtained by simply treating refraction and diffraction effects in consecutive steps through the combination of ray-based time of flight and diffractiontomography. This letter presents the first experimental demonstration of the method using phantom and invivo data from a cancer patient.
132(2012); http://dx.doi.org/10.1121/1.4740493View Description Hide Description
Supplying sufficient early reflections to audience members is an important prerequisite to good acoustic quality in performing arts spaces. However, the relationship between the geometry of a room and its acoustic efficiency in terms of early energy has rarely been investigated using basic geometrical principles. The present study demonstrates the possibility of predicting the average value of early reflected energy across the audience area using solid angles. The formulas obtained display the influence of various factors on average early energy; in particular, the direction of arrival of early reflections is found to play a significant role, which highlights interesting implications for the acoustic design of concert halls.
132(2012); http://dx.doi.org/10.1121/1.4740489View Description Hide Description
The localization of active speakers with microphone arrays is an active research line with a considerable interest in many acoustic areas. Many algorithms for source localization are based on the computation of the Generalized Cross-Correlation function between microphone pairs employing phase transform weighting. Unfortunately, the performance of these methods is severely reduced when wall reflections and multiple sound sources are present in the acoustic environment. As a result, estimating the number of active sound sources and their actual directions becomes a challenging task. To effectively tackle this problem, a Bayesian inference framework is proposed. Based on a nested sampling algorithm, a mixture model and its parameters are estimated, indicating both the number of sources—model selection—and their angle of arrival—parameter estimation, respectively. A set of measured data demonstrates the accuracy of the proposed model.
- GENERAL LINEAR ACOUSTICS 
Generalized method of moments: A boundary integral framework for adaptive analysis of acoustic scattering132(2012); http://dx.doi.org/10.1121/1.4740488View Description Hide Description
Boundary integralequations (BIEs) find applications in problems ranging from sonar to medical diagnostics. The two ingredients of the BIE solution technique are (1) representation of the domain and (2) design of approximation spaces to represent physical quantities on the domain. These, in concert, affect accuracy and convergence of the simulation. This paper presents a framework that permits the development of a scheme for refinement (of size and order) in both geometry and function representations. Further, this permits flexibility in the types of basis functions that can be used. Capabilities of the proposed framework are shown via a number of numerical examples.
132(2012); http://dx.doi.org/10.1121/1.4730897View Description Hide Description
A pseudospectral model of linear elastic wave propagation is described based on the first order stress-velocity equations of elastodynamics. k-space adjustments to the spectral gradient calculations are derived from the dyadic Green’s functionsolution to the second-order elastic waveequation and used to (a) ensure the solution is exact for homogeneous wave propagation for timesteps of arbitrarily large size, and (b) also allows larger time steps without loss of accuracy in heterogeneous media. The formulation in k-space allows the wavefield to be split easily into compressional and shear parts. A perfectly matched layer (PML) absorbing boundary condition was developed to effectively impose a radiation condition on the wavefield. The staggered grid, which is essential for accurate simulations, is described, along with other practical details of the implementation. The model is verified through comparison with exact solutions for canonical examples and further examples are given to show the efficiency of the method for practical problems. The efficiency of the model is by virtue of the reduced point-per-wavelength requirement, the use of the fast Fourier transform (FFT) to calculate the gradients in k space, and larger time steps made possible by the k-space adjustments.
- NONLINEAR ACOUSTICS 
132(2012); http://dx.doi.org/10.1121/1.4740491View Description Hide Description
Acoustoelasticity, or the change in elastic wave speeds with stress, is a well-studied phenomenon for bulk waves. The effect of stress on Lamb waves is not as well understood, although it is clear that anisotropic stresses will produce anisotropy in the Lamb wave dispersion curves. Here the theory of acoustoelastic Lamb wave propagation is developed for isotropic media subjected to a biaxial, homogeneous stress field. It is shown that, as expected, dispersion curves change anisotropically for most stresses, modes, and frequencies. Interestingly, for some mode-frequency combinations, changes in phase velocity are isotropic even for a biaxial stress field. Theoretical predictions are compared to experimental results for several Lamb wave modes and frequencies for uniaxial loads applied to an aluminum plate, and the agreement is reasonably good.
- AEROACOUSTICS, ATMOSPHERIC SOUND 
132(2012); http://dx.doi.org/10.1121/1.4742972View Description Hide Description
An exact solution of the acoustic field around the rotating dipole source has been derived by using a series expansion method and the gradient calculation in the spherical and cylindrical coordinate systems which extends a previously published solution for a rotating monopole source. The proposed exact solution establishes an analytical method to predict the sound radiated from the rotating blades once the acoustic sources have been known.