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Journal of the Acoustical Society of America

A V Shanin
The precursor wave (often called the first arriving signal) in a layered waveguide is investigated. It is known that the velocity of such a signal is close to the velocity of the fastest medium in the waveguide, and it may be bigger than the fastest group velocity given by the dispersion diagram of the waveguide. Usually the precursor pulse decays with the propagation distance. A model layered waveguide is studied in the paper. It is shown that the precursor is associated with the pseudo-branch structure of the dispersion diagram...
January 2017: Journal of the Acoustical Society of America
Matthieu Gallezot, Fabien Treyssède, Laurent Laguerre
The modal analysis of wave problems of unbounded type involves a continuous sum of radiation modes. This continuum is difficult to handle mathematically and physically. It can be approximated by a discrete set of leaky modes, corresponding to improper modes growing to infinity. Perfectly matched layers (PMLs) have been widely applied in numerical methods to efficiently simulate infinite media, most often without considering a modal approach. This letter aims to bring insight into the modal basis computed with PMLs...
January 2017: Journal of the Acoustical Society of America
(no author information available yet)
No abstract text is available yet for this article.
January 2017: Journal of the Acoustical Society of America
Guangying Zheng, Yiwang Huang, Jian Hua, Xiuyu Xu, Fei Wang
A corrected effective density fluid model is developed for predicting sound speed dispersion and attenuation coefficient in gassy sediments. An acoustic experiment was undertaken to measure the attenuation coefficient in a frequency band of 600 to 3000 Hz in gassy unsaturated sand. The measured frequency spectra of the attenuation coefficient show four peaks due to bubble resonance. Then a method of using several modified Gaussian functions to model bubble size distribution is proposed to fit measured attenuation data, which shows that the magnitudes of the fitted model attenuation coefficients are broadly in agreement with those measured attenuation data...
January 2017: Journal of the Acoustical Society of America
Efren Fernandez-Grande, Angeliki Xenaki, Peter Gerstoft
This study examines a near-field acoustic holography method consisting of a sparse formulation of the equivalent source method, based on the compressive sensing (CS) framework. The method, denoted Compressive-Equivalent Source Method (C-ESM), encourages spatially sparse solutions (based on the superposition of few waves) that are accurate when the acoustic sources are spatially localized. The importance of obtaining a non-redundant representation, i.e., a sensing matrix with low column coherence, and the inherent ill-conditioning of near-field reconstruction problems is addressed...
January 2017: Journal of the Acoustical Society of America
K Apostolopoulos, E Pappa, D Deligianni
Strain-dependence of ultrasound speed in cancellous bone was determined by applying a range of uniaxial compressive strains in the elasticity region, in a single direction, parallel or perpendicular to the propagating wave. Compressive strain modulated the ultrasound speed significantly. The decrease of ultrasound speed was found to change linearly as a function of strain. The changes of broadband ultrasound attenuation were also determined for the two dilatational waves (parallel or perpendicular to the strain)...
January 2017: Journal of the Acoustical Society of America
Jie Li, Peter Gerstoft, Dazhi Gao, Guofu Li, Ning Wang
The backscattered travel-time structure is obtained by cross-correlating air-acoustic ocean surf noise recorded on microphone pairs (separation ∼2 m) on the beach. The scatterer is a 20 cm radius Polyvinyl chloride pipe 2.5 m landside of the microphone array. Arrivals corresponding to the time-difference (travel-time difference between two scatterer-receiver paths) and scattered (travel time for receiver-scatterer-receiver path) waves emerge in the cross-correlation functions in a backscattering configuration...
January 2017: Journal of the Acoustical Society of America
Neil B Stremmel, Christopher J Struck
American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes a catalog of Acoustical American National Standards. To receive a copy of the latest Standards catalog, please contact Neil Stremmel.Comments are welcomed on all material in Acoustical Standards News...
January 2017: Journal of the Acoustical Society of America
Stéphane Griffiths, Benoit Nennig, Stéphane Job
A theoretical and experimental study of the acoustic absorption of granular porous media made of non-cohesive piles of spherical shells is presented. These shells are either rigid or elastic, possibly drilled with a neck (Helmholtz resonators), and either porous or impervious. A description is given of acoustic propagation through these media using the effective medium models proposed by Johnson (rigid particles) and Boutin (rigid Helmholtz resonators), which are extended to the configurations studied in this work...
January 2017: Journal of the Acoustical Society of America
Xiaolei Li, Gaokun Yu, Ning Wang, Dazhi Gao, Haozhong Wang
Monochromatic sound source localization becomes difficult in enclosed space. According to the reciprocity theorem, a self-consistent method of source localization in enclosed space, referred to as the flux projection beamforming, is proposed, only using the measurement of the sound pressure and normal velocity on the closed boundary at a single frequency. Its validity is examined both by experiment and simulation.
January 2017: Journal of the Acoustical Society of America
Bonnie K Lau, Kaylah Lalonde, Monika-Maria Oster, Lynne A Werner
Although recent results show that 3-month-olds can discriminate complex tones by their missing fundamental, it is arguable whether they are discriminating on the basis of a perceived pitch. A defining characteristic of pitch is that it carries melodic information. This study investigated whether 3-month-olds, 7-month-olds, and adults can detect a change in a melody composed of missing fundamental complexes. Participants heard a seven-note melody and learned to respond to a change that violated the melodic contour...
January 2017: Journal of the Acoustical Society of America
Elaine Moran
not available.
January 2017: Journal of the Acoustical Society of America
Morwaread M Farbood, Khen C Price
Timbre is an auditory feature that has received relatively little attention in empirical work examining musical tension. In order to address this gap, an experiment was conducted to explore the contribution of several specific timbre attributes-inharmonicity, roughness, spectral centroid, spectral deviation, and spectral flatness-to the perception of tension. Listeners compared pairs of sounds representing low and high degrees of each attribute and indicated which sound was more tense. Although the response profiles showed that the high states corresponded with increased tension for all attributes, further analysis revealed that some attributes were strongly correlated with others...
January 2017: Journal of the Acoustical Society of America
Andrew N Norris
Total absorption, defined as the net flux of energy out of a bounded region averaged over one cycle for time harmonic motion, must be non-negative when there are no sources of energy within the region. This passivity condition places constraints on the non-dimensional absorption coefficients of longitudinal and transverse waves, γL and γT, in isotropic linearly viscoelastic materials. Typically, γL, γT are small, in which case the constraints imply that coefficients of attenuation per unit length, αL, αT, must satisfy the inequality αL/αT≥4cT(3)/3cL(3) where cL, cT are the wave speeds...
January 2017: Journal of the Acoustical Society of America
Tudor-Cătălin Zorilă, Yannis Stylianou, Sheila Flanagan, Brian C J Moore
Four algorithms designed to enhance the intelligibility of speech when noise is added after processing were evaluated under the constraint that the speech should have the same loudness before and after processing, as determined using a loudness model. The algorithms applied spectral modifications and two of them included dynamic-range compression. On average, the methods with dynamic-range compression required the least level adjustment to equate loudness for the unprocessed and processed speech. Subjects with normal-hearing (experiment 1) and mild-to-moderate hearing loss (experiment 2) were tested using unmodified and enhanced speech presented in speech-shaped noise (SSN) and a competing speaker (CS)...
January 2017: Journal of the Acoustical Society of America
A Klein, C Marquis-Favre, P Champelovier
Due to the expansion of urban areas, an increasing number of residents are exposed to combined community noise sources. Studies show that the exposure to transportation noise significantly affects health and well-being. Noise annoyance is one of these adverse health effects. Up to now, annoyance due to transportation noise is mostly assessed considering single noise exposure situations neglecting the effects of potential interactions between noise sources. In this study, perceptual phenomena involved in noise annoyance due to combined urban road traffic and tramway noises are assessed in laboratory conditions with imaginary and simulated contexts...
January 2017: Journal of the Acoustical Society of America
Chris Bibby, Murray Hodgson
The work reported here, part of a study on the performance and optimal design of interior natural-ventilation openings and silencers ("ventilators"), discusses the prediction of the acoustical performance of such ventilators, and the factors that affect it. A wave-based numerical approach-the finite-element method (FEM)-is applied. The development of a FEM technique for the prediction of ventilator diffuse-field transmission loss is presented. Model convergence is studied with respect to mesh, frequency-sampling and diffuse-field convergence...
January 2017: Journal of the Acoustical Society of America
Valentin Popov, Roland Langrock, Stacy L DeRuiter, Fleur Visser
Vocalizations of cetaceans form a key component of their social interactions. Such vocalization activity is driven by the behavioral states of the whales, which are not directly observable, so that latent-state models are natural candidates for modeling empirical data on vocalizations. In this paper, hidden Markov models are used to analyze calling activity of long-finned pilot whales (Globicephala melas) recorded over three years in the Vestfjord basin off Lofoten, Norway. Baseline models are used to motivate the use of three states, while more complex models are fit to study the influence of covariates on the state-switching dynamics...
January 2017: Journal of the Acoustical Society of America
Gareth J Bennett, David B Stephens, Francisco Rodriguez Verdugo
This paper investigates the interaction between the shear-layer over a circular cavity with a relatively small opening and the flow-excited acoustic response of the volume within to shear-layer instability modes. Within the fluid-resonant category of cavity oscillation, most research has been conducted on rectangular geometries: generally restricted to longitudinal standing waves, or when cylindrical: to Helmholtz resonance. In practical situations, however, where the cavity is subject to a range of flow speeds, many different resonant mode types may be excited...
January 2017: Journal of the Acoustical Society of America
A Moleti, D Pistilli, R Sisto
Stimulus-frequency, transient-evoked, and distortion product otoacoustic emissions (OAEs) have been measured in eight normal-hearing human ears over a wide stimulus level range, with high spectral resolution. The single-reflection component of the response was isolated using time-frequency filtering, and its average delay was measured as a function of frequency and stimulus level. The apical-basal transition was studied by fitting the average delay of the filtered single-reflection OAEs, expressed in number of cycles, to a three-slope power-law function with two knot frequencies...
January 2017: Journal of the Acoustical Society of America
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