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Journal of the Acoustical Society of America

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https://www.readbyqxmd.com/read/28040053/toward-mechanistic-understanding-of-the-relationship-between-the-sound-absorption-and-the-natural-and-resonant-frequencies-of-porous-media
#1
A Hasani Baferani, A R Ohadi, R Keshavarz
In this paper, the natural and resonant frequencies of porous media are studied based on Biot's equations. The governing equations of porous media are analytically solved by using the recent developed potential function method. Based on the obtained results, the natural and resonant frequencies of the porous medium can be investigated. In this research, several foams with different acoustical and non-acoustical properties are considered and the natural and resonant frequencies are studied. In addition, for a better understanding of the natural and variation of resonant frequencies of the considered foams, various damping gains are defined and by changing them gradually, the variations of absorption coefficient and field variables are studied...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040052/examination-of-the-reflection-properties-of-sloping-terminations-to-organ-pipes
#2
Péter Rucz, Kai Dolde, Wei Kuang, Judit Angster, András Miklós
The sound characteristics of both labial and lingual organ pipes are affected to a great extent by the reflection properties of the resonators. In this paper, the reflection properties of sloped pipe terminations are examined and the possible applications in organ building practice are investigated. Sloped shallots of reed organ pipes with different termination angles are of particular interest in this study. For the examination of the reflection properties two different approaches are applied. Sound pulse reflection measurements on model geometries provide experimental data in the time domain, while finite element simulations yield reflection coefficients in the frequency domain...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040051/geoacoustic-inversion-for-the-seabed-transition-layer-using-a-bernstein-polynomial-model
#3
Jorge E Quijano, Stan E Dosso, Jan Dettmer, Charles Holland
This paper develops an inversion method for the seabed transition layer at the water-sediment interface, often found in muddy sediments, which provides density and sound-speed profiles that were previously not resolvable. The resolution improvements are achieved by introducing a parametrization that captures general depth-dependent gradients in geoacoustic parameters with a small number of parameters. In particular, the gradients are represented by a sum of Bernstein basis functions, weighted by unknown coefficients...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040050/interference-effects-in-phased-beam-tracing-using-exact-half-space-solutions
#4
Matthew A Boucher, Bert Pluymers, Wim Desmet
Geometrical acoustics provides a correct solution to the wave equation for rectangular rooms with rigid boundaries and is an accurate approximation at high frequencies with nearly hard walls. When interference effects are important, phased geometrical acoustics is employed in order to account for phase shifts due to propagation and reflection. Error increases, however, with more absorption, complex impedance values, grazing incidence, smaller volumes and lower frequencies. Replacing the plane wave reflection coefficient with a spherical one reduces the error but results in slower convergence...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040049/ambient-noise-correlations-on-a-mobile-deformable-array
#5
Perry Naughton, Philippe Roux, Riley Yeakle, Curt Schurgers, Ryan Kastner, Jules S Jaffe, Paul L D Roberts
This paper presents a demonstration of ambient acoustic noise processing on a set of free floating oceanic receivers whose relative positions vary with time. It is shown that it is possible to retrieve information that is relevant to the travel time between the receivers. With thousands of short time cross-correlations (10 s) of varying distance, it is shown that on average, the decrease in amplitude of the noise correlation function with increased separation follows a power law. This suggests that there may be amplitude information that is embedded in the noise correlation function...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040048/noise-sensitivity-and-loudness-derivative-index-for-urban-road-traffic-noise-annoyance-computation
#6
Laure-Anne Gille, Catherine Marquis-Favre, Reinhard Weber
Urban road traffic composed of powered-two-wheelers (PTWs), buses, heavy, and light vehicles is a major source of noise annoyance. In order to assess annoyance models considering different acoustical and non-acoustical factors, a laboratory experiment on short-term annoyance due to urban road traffic noise was conducted. At the end of the experiment, participants were asked to rate their noise sensitivity and to describe the noise sequences they heard. This verbalization task highlights that annoyance ratings are highly influenced by the presence of PTWs and by different acoustical features: noise intensity, irregular temporal amplitude variation, regular amplitude modulation, and spectral content...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040047/bats-adjust-their-pulse-emission-rates-with-swarm-size-in-the-field
#7
Yuan Lin, Nicole Abaid, Rolf Müller
Flying in swarms, e.g., when exiting a cave, could pose a problem to bats that use an active biosonar system because the animals could risk jamming each other's biosonar signals. Studies from current literature have found different results with regard to whether bats reduce or increase emission rate in the presence of jamming ultrasound. In the present work, the number of Eastern bent-wing bats (Miniopterus fuliginosus) that were flying inside a cave during emergence was estimated along with the number of signal pulses recorded...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040046/diffusion-tensor-imaging-reveals-changes-in-the-adult-rat-brain-following-long-term-and-passive-moderate-acoustic-exposure
#8
Sherwin Abdoli, Leon C Ho, Jevin W Zhang, Celia M Dong, Condon Lau, Ed X Wu
This study investigated neuroanatomical changes following long-term acoustic exposure at moderate sound pressure level (SPL) under passive conditions, without coupled behavioral training. The authors utilized diffusion tensor imaging (DTI) to detect morphological changes in white matter. DTIs from adult rats (n = 8) exposed to continuous acoustic exposure at moderate SPL for 2 months were compared with DTIs from rats (n = 8) reared under standard acoustic conditions. Two distinct forms of DTI analysis were applied in a sequential manner...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040045/compressive-spherical-beamforming-for-localization-of-incipient-tip-vortex-cavitation
#9
Youngmin Choo, Woojae Seong
Noises by incipient propeller tip vortex cavitation (TVC) are generally generated at regions near the propeller tip. Localization of these sparse noises is performed using compressive sensing (CS) with measurement data from cavitation tunnel experiments. Since initial TVC sound radiates in all directions as a monopole source, a sensing matrix for CS is formulated by adopting spherical beamforming. CS localization is examined with known source acoustic measurements, where the CS estimated source position coincides with the known source position...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040044/lateralization-of-simulated-sources-and-echoes-differing-in-frequency-based-on-interaural-temporal-differences
#10
Raymond H Dye, Joseph Boomer, Joleen Frankel, Jacquelyn P Hill, Alycia N Peloquin
This study examined listeners' ability to process interaural temporal differences (ITDs) in one of two sequential sounds when the two differed in spectral content. A correlational analysis assessed weights given to ITDs of simulated source and echo pulses for echo delays of 8-128 ms for conditions in which responses were based on the source or echo, a 3000-Hz Gaussian (target) pulse. The other (distractor) pulse was spectrally centered at 1500, 2000, 3000, 4000, or 5000 Hz. Also measured were proportion correct and proportion of responses predicted from the weights...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040043/relationships-of-linear-and-nonlinear-ultrasound-parameters-with-porosity-and-trabecular-spacing-in-trabecular-bone-mimicking-phantoms
#11
Kang Il Lee
The speed of sound (SOS), the normalized broadband ultrasound attenuation (nBUA), and the nonlinear parameter (B/A) were measured in 18 trabecular-bone-mimicking phantoms consisting of water-saturated aluminum foams. The strong slow wave and the very weak fast wave were consistently observed in the signals transmitted through all of the phantoms. It was found that the SOS increased as the porosity and the trabecular spacing increased. In contrast, both the nBUA and the B/A showed opposite dependences on the porosity and the trabecular spacing...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040042/multichannel-active-noise-control-for-spatially-sparse-noise-fields
#12
Jihui Zhang, Thushara D Abhayapala, Prasanga N Samarasinghe, Wen Zhang, Shouda Jiang
Multi-channel active noise control (ANC) is currently an attractive solution for the attenuation of low-frequency noise fields, in three-dimensional space. This paper develops a controller for the case when the noise source components are sparsely distributed in space. The anti-noise signals are designed as in conventional ANC to minimize the residual errors but with an additional term containing an ℓl norm regularization applied to the signal magnitude. This results in that only secondary sources close to the noise sources are required to be active for cancellation of sparse noise fields...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040041/consistent-sound-change-between-stops-and-affricates-in-seoul-korean-within-and-across-individuals-a-diachronic-investigation
#13
Hyunjung Lee
This study investigated whether sound change that Korean stops currently undergo occurred consistently for affricates at both the group and individual levels. This study compared the duration and F0 properties of Seoul Korean stops to those of the affricates produced by older and younger speakers. Group results showed consistent sound change between the two consonant manner types. In addition, individual examination indicated stability in use of duration and F0 within an individual, and enabled further understanding of the group pattern...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040040/th%C3%A3-venin-acoustics
#14
Randall P Williams, Neal A Hall
Thévenin's theorem is commonly used in the analysis of acoustic transducers to provide a simplified representation of a transducer or its environment. The method may be extended to the analyses of other acoustic systems, without limitation to systems that have been reduced to analogous circuit models, and is particularly convenient in the analysis of acoustic scattering when the scattering object is mobile. In this paper, the method is illustrated through an alternative derivation of the well-known "mass law" for transmission through a partition, and is also applied to the case of acoustic scattering from a rigid, mobile cylinder of arbitrary size in an ideal plane progressive wave...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040039/a-fourier-based-total-field-scattered-field-technique-for-three-dimensional-broadband-simulations-of-elastic-targets-near-a-water-sand-interface
#15
Yu Shao, Shumin Wang
The numerical simulation of acoustic scattering from elastic objects near a water-sand interface is critical to underwater target identification. Frequency-domain methods are computationally expensive, especially for large-scale broadband problems. A numerical technique is proposed to enable the efficient use of finite-difference time-domain method for broadband simulations. By incorporating a total-field/scattered-field boundary, the simulation domain is restricted inside a tightly bounded region. The incident field is further synthesized by the Fourier transform for both subcritical and supercritical incidences...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040038/effects-of-age-and-hearing-loss-on-concurrent-vowel-identification
#16
Ananthakrishna Chintanpalli, Jayne B Ahlstrom, Judy R Dubno
Differences in formant frequencies and fundamental frequencies (F0) are important cues for segregating and identifying two simultaneous vowels. This study assessed age- and hearing-loss-related changes in the use of these cues for recognition of one or both vowels in a pair and determined differences related to vowel identity and specific vowel pairings. Younger adults with normal hearing, older adults with normal hearing, and older adults with hearing loss listened to different-vowel and identical-vowel pairs that varied in F0 differences...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040037/acoustics-from-a-rectangular-supersonic-nozzle-exhausting-over-a-flat-surface
#17
Pablo Mora, Florian Baier, K Kailasanath, Ephraim J Gutmark
A jet exhausting over a plate at different distances away from the nozzle was investigated to simulate jets exhausting over airframe surfaces and the jet-ground interaction during take-off and landing operations. A supersonic rectangular nozzle of 2:1 aspect ratio and 1.5 design Mach number was tested with and without the plate. Far-field acoustics from the cold and heated jets at over-expanded, design, and under-expanded conditions were measured at the reflected, sideline, and shielded azimuthal directions...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040036/on-the-dimensionality-of-elastic-wave-scattering-within-heterogeneous-media
#18
Anton Van Pamel, Peter B Nagy, Michael J S Lowe
Elastic waves scatter when the wavelength becomes comparable to random spatial fluctuations in the elastic properties of the propagation medium. It is postulated that within the long-wavelength Rayleigh regime, the scattering induced attenuation obeys a D = 1,2,3 dimensional dependence on wavenumber, k(D)(+1), whilst within the shorter-wavelength stochastic regime, it becomes independent of the dimensions and thus varies as k(2). These predictions are verified numerically with a recently developed finite element method in three dimensions (3D), two dimensions (2D), and one dimension (1D), for the example of ultrasonic waves propagating within polycrystalline materials...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040035/infant-directed-speech-reduces-english-learning-infants-preference-for-trochaic-words
#19
Yuanyuan Wang, Christopher S Lee, Derek M Houston
Over the past couple of decades, research has established that (1) infant-directed speech (IDS) facilitates speech, language, and cognitive development; and (2) infants are sensitive to the rhythmic structures in the ambient language. However, little is known about the role of IDS in infants' processing of rhythmic structures. Building on these two lines of research, whether IDS enhances infants' sensitivity to the predominant stress pattern (trochaic) in English was asked. To address this question, 9-month-old American infants were familiarized and tested with both trochaic (e...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040034/automatic-measurement-of-vowel-duration-via-structured-prediction
#20
Yossi Adi, Joseph Keshet, Emily Cibelli, Erin Gustafson, Cynthia Clopper, Matthew Goldrick
A key barrier to making phonetic studies scalable and replicable is the need to rely on subjective, manual annotation. To help meet this challenge, a machine learning algorithm was developed for automatic measurement of a widely used phonetic measure: vowel duration. Manually-annotated data were used to train a model that takes as input an arbitrary length segment of the acoustic signal containing a single vowel that is preceded and followed by consonants and outputs the duration of the vowel. The model is based on the structured prediction framework...
December 2016: Journal of the Acoustical Society of America
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