• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Mar 2010

Volume 127, Issue 3, pp. EL87-2044

Page 1 of 59 Pages Next Page | Jump to Page
back to top
RSS Feeds
FREE

The use of interaural time and level difference cues by bilateral cochlear implant users

Justin M. Aronoff, Yang-soo Yoon, Daniel J. Freed, Andrew J. Vermiglio, Ivan Pal, and Sigfrid D. Soli

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. EL87-EL92 (2010); (6 pages) | Cited 10 times

Online Publication Date: 09 Feb 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
While considerable evidence suggests that bilateral cochlear implant (CI) users’ sound localization abilities rely primarily on interaural level difference (ILD) cues, and only secondarily, if at all, on interaural time difference (ITD) cues, this evidence has largely been indirect. This study used head-related transfer functions (HRTFs) to independently manipulate ITD and ILD cues and directly measure their contribution to bilateral CI users’ localization abilities. The results revealed a strong reliance on ILD cues, but some CI users also made use of ITD cues. The results also suggest a complex interaction between ITD and ILD cues.
Show PACS
43.66.Pn Binaural hearing
43.66.Qp Localization of sound sources
43.66.Ts Auditory prostheses, hearing aids
FREE

Retrieving the exact Green’s function by wavefield crosscorrelation

Yingcai Zheng

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. EL93-EL98 (2010); (6 pages) | Cited 5 times

Online Publication Date: 09 Feb 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Recent development on the Green’s function retrieval by wavefield crosscorrelation has substantially advanced the physical research in a multidisciplinary and unprecedented fashion. However, the underlying assumption of the theory that the sources are in the far-field limits the technology to extracting only the high-frequency part of the Green’s function in an open system. This critical approximation can be eliminated using the exact boundary integral equation method. A scheme involving the crosscorrelation kernel is proposed to recover the exact Green’s function including all-frequency content. Symmetric difference kernels are analytically constructed for sources on a plane or on a circle and can be reduced to the known Dirac delta kernel under the far-field approximation.
Show PACS
43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation
FREE

On the subtraction method for in-situ reflection and diffusion coefficient measurements

Philip Robinson and Ning Xiang

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. EL99-EL104 (2010); (6 pages) | Cited 2 times

Online Publication Date: 11 Feb 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The subtraction method is a technique critical to several important acoustic measurements. It involves subtracting a reference measurement including only direct sound from one with direct sound and a reflection, to isolate the reflection. The process is very sensitive to environmental conditions, such as changes in temperature, air movement, and microphone positioning. These variations cause small time differences between the reference and reflection measurements, which prevent complete subtraction of the direct sound; the residual direct sound then pollutes analysis of the isolated reflection. This work evaluates methods to compensate for differences to achieve minimal interference from the residual direct sound.
Show PACS
43.58.Bh Acoustic impedance measurement
43.58.Vb Calibration of acoustical devices and systems
43.55.Ev Sound absorption properties of materials: theory and measurement of sound absorption coefficients; acoustic impedance and admittance
FREE

Why are natural sounds detected faster than pips?

Clara Suied, Patrick Susini, Stephen McAdams, and Roy D. Patterson

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. EL105-EL110 (2010); (6 pages) | Cited 2 times

Online Publication Date: 11 Feb 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Simple reaction times (RTs) were used to measure differences in processing time between natural animal sounds and artificial sounds. When the artificial stimuli were sequences of short tone pulses, the animal sounds were detected faster than the artificial sounds. The animal sounds were then compared with acoustically modified versions (white noise modulated by the temporal envelope of the animal sounds). No differences in RTs were observed between the animal sounds and their modified counterparts. These results show that the fast detection observed for natural sounds, in the present task, could be explained by their acoustic properties.
Show PACS
43.66.Lj Perceptual effects of sound
FREE

The behavioral audiogram of whitetail deer (Odocoileus virginianus)

Henry Heffner, Jr. and Henry E. Heffner

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. EL111-EL114 (2010); (4 pages) | Cited 2 times

Online Publication Date: 11 Feb 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The behavioral audiograms of two female white-tailed deer (Odocoileus virginianus) were determined using a conditioned-suppression avoidance procedure. At a level of 60 dB sound pressure level, their hearing range extends from 115 Hz to 54 kHz with a best sensitivity of −3 dB at 8 kHz; increasing the intensity of the sound extends their hearing range from 32 Hz (at 96.5 dB) to 64 kHz (at 93 dB). Compared with humans, white-tailed deer have better high-frequency but poorer low-frequency hearing.
Show PACS
43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.66.Gf Detection and discrimination of sound by animals
43.66.Cb Loudness, absolute threshold
FREE

Dispersion of sound in dilute suspensions with nonlinear particle relaxation

Max Kandula

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. EL115-EL120 (2010); (6 pages)

Online Publication Date: 17 Feb 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The theory accounting for nonlinear particle relaxation (viscous and thermal) has been applied to the prediction of dispersion of sound in dilute suspensions. The results suggest that significant deviations exist for sound dispersion between the linear and nonlinear theories at large values of ωτd, where ω is the circular frequency and τd is the Stokesian particle relaxation time. It is revealed that the nonlinear effect on the dispersion coefficient due to viscous contribution is larger relative to that of thermal conduction.
Show PACS
43.20.Hq Velocity and attenuation of acoustic waves
43.50.Nm Aerodynamic and jet noise
43.50.Gf Noise control at source: redesign, application of absorptive materials and reactive elements, mufflers, noise silencers, noise barriers, and attenuators, etc.
back to top
RSS Feeds

Causal analysis of the viscoelastic Lamb problem

André Moura

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1185-1188 (2010); (4 pages)

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A mathematical development is given for the generation of viscoelastic waves by an impulsive line source acting on the interface of a viscoelastic half space, where the viscoelasticity is characterized by two relaxation processes. The considered idealized viscoelastic medium is isotropic and characterized by two Lamé constants appropriate for low frequencies, by their increments associated with the shift from low to high frequencies, and by separate relation times associated with each of the Lamé constants. A causal solution is developed using integral transforms and an extension of Cagniard's method
Show PACS
43.35.Mr Acoustics of viscoelastic materials
43.20.Bi Mathematical theory of wave propagation
43.20.Px Transient radiation and scattering

Observation of energy cascade creating periodic shock waves in a resonator

Tetsushi Biwa and Taichi Yazaki

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1189-1192 (2010); (4 pages) | Cited 3 times

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nonlinear excitation of periodic shock waves in high-amplitude standing waves was studied from measurements of the acoustic intensity. A gas column of atmospheric air in a cylindrical resonator was driven sinusoidally by an oscillating piston at the fundamental resonance frequency. Acoustic pressure and axial acoustic particle velocity were simultaneously measured and decomposed into the Fourier components, from which the intensity associated with each of the oscillating modes in the resonator was determined. This letter reports the energy cascade from the driven mode to the second harmonic in the periodic shock waves in the resonator.
Show PACS
43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves
43.35.Ud Thermoacoustics, high temperature acoustics, photoacoustic effect

Active control of one-dimension impulsive reflection based on a prediction method

Ning Han, Shengzhen Feng, and Xiaojun Qiu

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1193-1196 (2010); (4 pages) | Cited 1 time

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An approach for predicting the reflected sound pressure is proposed in one-dimensional sound field. For a duct ended with a rigid reflective surface, only one microphone is required to measure the total sound pressure on the surface, which is further used as the error sensing strategy in an active noise control (ANC) system to reduce the in-duct reflection. Experiments are carried out to validate the prediction method, and a broadband feedforward ANC system is implemented to suppress the impulsive reflection. It is found that the ANC system based on the reflected sound prediction is effective, and 12.2 dB attenuation of the one-dimension impulsive reflection is obtained after the active control.
Show PACS
43.50.Ki Active noise control
back to top
RSS Feeds

High frequency poroelastic waves in hydrogels

Piero Chiarelli, Antonio Lanatà, Marina Carbone, and Claudio Domenici

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1197-1207 (2010); (11 pages) | Cited 1 time

Online Publication Date: 23 Mar 2010

Full Text: | Download PDF

Show Abstract
In this work a continuum model for high frequency poroelastic longitudinal waves in hydrogels is presented. A viscoelastic force describing the interaction between the polymer network and the bounded water present in such materials is introduced. The model is tested by means of ultrasound wave speed and attenuation measurements in polyvinylalcohol hydrogel samples. The theory and experiments show that ultrasound attenuation decreases linearly with the increase in the water volume fraction β of the hydrogel. The introduction of the viscoelastic force between the bounded water and the polymer network leads to a bi-phasic theory, showing an ultrasonic fast wave attenuation that can vary as a function of the frequency with a non-integer exponent in agreement with the experimental data in literature. When β tends to 1 (100% of interstitial water) due to the presence of bounded water in the hydrogel, the ultrasound phase velocity acquires higher value than that of pure water. The ultrasound speed gap at β = 1 is confirmed by the experimental results, showing that it increases in less cross-linked gel samples which own a higher concentration of bounded water.
Show PACS
43.20.Jr Velocity and attenuation of elastic and poroelastic waves
43.20.Bi Mathematical theory of wave propagation
43.80.Cs Acoustical characteristics of biological media: molecular species, cellular level tissues
43.80.Ev Acoustical measurement methods in biological systems and media
back to top
RSS Feeds

Self-demodulation of high-frequency ultrasound

Hendrik J. Vos, David E. Goertz, and Nico de Jong

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1208-1217 (2010); (10 pages) | Cited 2 times

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High-frequency (>10 MHz) ultrasound is used in, e.g., small animal imaging or intravascular applications. Currently available ultrasound contrast agents (UCAs) have a suboptimal response for high frequencies. This study therefore investigates the nonlinear propagation effects in a high-frequency ultrasound field (25 MHz) and its use for standard UCA and diagnostic frequencies (1–3 MHz). Nonlinear mixing of two high-frequency carrier waves produces a low-frequency wave, known as the self-demodulation or parametric array effect. Hydrophone experiments showed that the self-demodulated field of a focused 25 MHz transducer (850 kPa source pressure) has an amplitude of 45 kPa at 1.5 MHz in water. Such pressure level is sufficient for UCA excitation. Experimental values are confirmed by numerical simulations using the Khokhlov–Zabolotskaya–Kuznetsov equation on a spatially convergent grid.
Show PACS
43.25.Lj Parametric arrays, interaction of sound with sound, virtual sources
43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves
43.25.Jh Reflection, refraction, interference, scattering, and diffraction of intense sound waves

Acoustic microstreaming around an encapsulated particle

Alexander A. Doinikov and Ayache Bouakaz

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1218-1227 (2010); (10 pages) | Cited 2 times

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A theory is suggested to calculate acoustic microstreaming that develops around an encapsulated particle in an ultrasound field. It is assumed that the particle is suspended in an unbounded fluid and can have a gas core or a liquid core. Fluids outside and inside the particle are assumed to be viscous and compressible. No restrictions are imposed on the size of the particle relative to the sound and viscous wavelengths in the outer and inner fluids, and all modes of the particle’s motion, including the surface ones, are taken into account. The shell of the particle is assumed to be an elastic viscous compressible medium. Solutions for the sound field within the shell are also valid for any ratio between the particle size and the sound and viscous wavelengths in the shell material. Numerical examples for the cases of an encapsulated gas bubble and an encapsulated particle with a liquid core are presented.
Show PACS
43.25.Nm Acoustic streaming
43.25.Yw Nonlinear acoustics of bubbly liquids

Modulation of ultrasound to produce multifrequency radiation force

Matthew W. Urban, Mostafa Fatemi, and James F. Greenleaf

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1228-1238 (2010); (11 pages) | Cited 3 times

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Dynamic radiation force has been used in several types of applications, and is performed by modulating ultrasound with different methods. By modulating ultrasound, energy can be transmitted to tissue, in this case a dynamic force to elicit a low frequency cyclic displacement to inspect the material properties of the tissue. In this paper, different types of modulation are explored including amplitude modulation (AM), double sideband suppressed carrier amplitude modulation AM, linear frequency modulation, and frequency-shift keying. Generalized theory is presented for computing the radiation force through the short-term time average of the energy density for these various types of modulation. Examples of modulation with different types of signals including sine waves, square waves, and triangle waves are shown. Using different modulating signals, multifrequency radiation force with different numbers of frequency components can be created, and can be used to characterize tissue mimicking materials and soft tissue. Results for characterization of gelatin phantoms using a method of vibrating an embedded sphere are presented. Different degrees of accuracy were achieved using different modulation techniques and modulating signals. Modulating ultrasound is a very flexible technique to produce radiation force with multiple frequency components that can be used for various applications.
Show PACS
43.25.Qp Radiation pressure
43.35.Yb Ultrasonic instrumentation and measurement techniques
43.35.Mr Acoustics of viscoelastic materials

Probing slow dynamics of consolidated granular multicomposite materials by diffuse acoustic wave spectroscopy

Nicolas Tremblay, Eric Larose, and Vincent Rossetto

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1239-1243 (2010); (5 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The stiffness of a consolidated granular medium experiences a drop immediately after a moderate mechanical solicitation. Then the stiffness rises back toward its initial value, following a logarithmic time evolution called slow dynamics. In the literature, slow dynamics has been probed by macroscopic quantities averaged over the sample volume, for instance, by the resonant frequency of vibrational eigenmodes. This article presents a different approach based on diffuse acoustic wave spectroscopy, a technique that is directly sensitive to the details of the sample structure. The parameters of the dynamics are found to depend on the damage of the medium. Results confirm that slow dynamics is, at least in part, due to tiny structural rearrangements at the microscopic scale, such as inter-grain contacts.
Show PACS
43.25.Ts Nonlinear acoustical and dynamical systems
43.35.Yb Ultrasonic instrumentation and measurement techniques
43.40.Le Techniques for nondestructive evaluation and monitoring, acoustic emission
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products
back to top
RSS Feeds

Detecting blast-induced infrasound in wind noise

Wheeler B. Howard, Kevin L. Dillion, and F. Douglas Shields

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1244-1250 (2010); (7 pages)

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Current efforts seek to monitor and investigate such naturally occurring events as volcanic eruptions, hurricanes, bolides entering the atmosphere, earthquakes, and tsunamis by the infrasound they generate. Often, detection of the infrasound signal is limited by the masking effect of wind noise. This paper describes the use of a distributed array to detect infrasound signals from four atmospheric detonations at White Sands Missile Range in New Mexico, USA in 2006. Three of the blasts occurred during times of low wind noise and were easily observed with array processing techniques. One blast was obscured by high wind conditions. The results of signal processing are presented that allowed localization of the blast-induced signals in the presence of wind noise in the array response.
Show PACS
43.28.Dm Infrasound and acoustic-gravity waves
43.28.Mw Shock and blast waves, sonic boom
43.60.Gk Space-time signal processing, other than matched field processing

A multi-mode screech frequency prediction formula for circular supersonic jets

J. H. Gao and X. D. Li

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1251-1257 (2010); (7 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A time evolution analysis is presented for the interaction between the instability waves, shock cells, and screech tones based on the authors’ previous numerical simulation database. An attachment and reinforcement process of the upstream propagating screech waves with the downstream hydrodynamic waves is identified and recognized as part of the screech loop. The first five shock cells are recognized as the effective sound source region. Through an analysis of the phase variation in the dominant pressure fluctuations for several typical Mach number screeching jets, it is found that the total number of the instability waves and the upstream feedback sound waves in the effective source region can be identified as 5 for the A1, B, and D modes and 6 for A2 and C modes, respectively. A screech tone frequency prediction formula is thus proposed based on this relation. The predicted screech wavelengths or Strouhal numbers of cold and hot jets all agree well with the experimental data by other researchers, except for a small discrepancy for the B mode. It is also noticed that the measured two A0 modes by Ponton et al. [NASA Technical Memorandum No. 113137, Langley Research Center (1997) ] can be classified to A1 and A2 modes, respectively, according to the proposed formula.
Show PACS
43.28.Ra Generation of sound by fluid flow, aerodynamic sound and turbulence
back to top
RSS Feeds

Application of the coherent-to-incoherent intensity ratio to estimation of ocean surface roughness from high-frequency, shallow-water propagation measurements

Philippe Roux, R. Lee Culver, and Shane Walker

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1258-1266 (2010); (9 pages) | Cited 2 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
For acoustic propagation through a shallow ocean channel or waveguide, the coherence between different transmissions is controlled primarily by the roughness of the ocean surface and to a lesser degree by fluctuations in the volume. In this study, the coherent-to-incoherent intensity ratio (CTIR) is defined as a way to quantify the coherence between multipath transmissions and ocean surface rms wave height and wind speed. A theory that connects the CTIR and the coherent surface reflection coefficient is developed using both Kirchhoff and small-slope approximations as rough surface scattering models. The CTIRs have been evaluated over a period of several days using broad-band experimental results from shallow-water deployment of source and receiver arrays that span most of the water column. Estimates of wind speed and rms wave height obtained using these CTIR calculations are compared with environmental measurements to demonstrate the validity of the theory.
Show PACS
43.30.Hw Rough interface scattering
43.30.Zk Experimental modeling
43.30.Gv Backscattering, echoes, and reverberation in water due to combinations of boundaries
back to top
RSS Feeds

Asymptotic evaluation of the pulse train radiated by an angled beam and fluid coupled rectangular ultrasonic transducer

D. D. Zakharov and L. Ju. Fradkin

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1267-1278 (2010); (12 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The near field underneath the ultrasonic probe fluid coupled to an isotropic solid is approximated in the frequency domain by a closed form asymptotic solution. The approximation is based on the problem decomposition and uses the stationary phase method evaluating the response to an equivalent surface source. This results in a sum of contributions, each dominating in a specific geometrical region, the main beam or a side lobe. The transitional zones are also described. The pulse trains are computed using the harmonic synthesis and compared with the results obtained by direct calculation of Fourier integrals. It is shown that the asymptotic approach permits us to elucidate the physics of problem and leads to a numerical algorithm which is about 104 times faster than the direct computations.
Show PACS
43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
43.20.Dk Ray acoustics
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products
43.20.Px Transient radiation and scattering

Using air-coupled sensors to determine the depth of a surface-breaking crack in concrete

Seong-Hoon Kee and Jinying Zhu

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1279-1287 (2010); (9 pages) | Cited 3 times

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Previous studies showed that the surface wave transmission coefficient across a surface-breaking crack in concrete can be used to estimate the crack depth. However, inconsistencies in the surface wave transmission measurements limit the test accuracy and application of this technique. The inconsistencies come from near-field scattering by the crack tip and inconsistent sensor coupling conditions on rough concrete surfaces. This study first investigates the near-field size based on numerical analyses, and then suggests that reliable surface wave transmission should be measured in the far field. Based on the far-field measurement, the relationship between the surface wave transmission ratio and the normalized crack depth (crack depth/wavelength) is obtained. In the experimental study, the air-coupled sensing method is proposed as a solution to the sensor coupling problem. Owing to the non-contact feature, the air-coupled sensing method not only improves testing speed but also enables more consistent signal measurement. The experimental study using air-coupled sensors shows good agreement with the results of numerical simulation and analytic solution.
Show PACS
43.35.Pt Surface waves in solids and liquids
43.20.Hq Velocity and attenuation of acoustic waves
43.20.El Reflection, refraction, diffraction of acoustic waves
back to top
RSS Feeds

Viscous damping and spring force in periodic perforated planar microstructures when the Reynolds’ equation cannot be applied

Dorel Homentcovschi and Ronald N. Miles

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1288-1299 (2010); (12 pages)

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A model of squeeze-film behavior is developed based on Stokes’ equations for viscous, compressible isothermal flows. The flow domain is an axisymmetrical, unit cell approximation of a planar, periodic, perforated microstructure. The model is developed for cases when the lubrication approximation cannot be applied. The complex force generated by vibrations of the diaphragm driving the flow has two components: the damping force and the spring force. While for large frequencies the spring force dominates, at low (acoustical) frequencies the damping force is the most important part. The analytical approach developed here yields an explicit formula for both forces. In addition, using a finite element software package, the damping force is also obtained numerically. A comparison is made between the analytic result, numerical solution, and some experimental data found in the literature, which validates the analytic formula and provides compelling arguments about its value in designing microelectomechanical devices.
Show PACS
43.38.Bs Electrostatic transducers
43.38.Kb Microphones and their calibration
back to top
RSS Feeds

Analysis of the attenuation of railway squeal noise by preloaded rings inserted in wheels

J. F. Brunel, P. Dufrénoy, J. Charley, and F. Demilly

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1300-1306 (2010); (7 pages)

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Squeal from railway wheels occurring in short radius curves produces a very intense and highly annoying noise in the range 400–8000 Hz. When the excitation, due to lateral forces acting on the wheel, cannot be avoided, additional systems can be added on the wheel to limit acoustic emission. A very economical approach is the use of metal rings inserted into grooves machined in the wheels. Unfortunately the effectiveness of these so called damping rings varies from one wheel to another and for different rings. Because the mechanisms of attenuation are not well understood, these variations have not to date been explained. The aim of this paper is to clarify the attenuation mechanisms for damping rings especially for the first three axial wheel modes, which are the predominant sound radiated ones in curve passage and for which the effectiveness of the treatment is lower. It has been generally assumed that friction between the ring and the groove has been the mechanism for squeal noise attenuation. Here it is shown that the vibration attenuation is due to modal coupling between the wheel and the ring. The validity of this proposed mechanism is investigated using experimental measurements and theoretical and numerical models. The results presented here will provide an avenue for optimization of the damping ring noise control treatment to obtain significant levels of squeal noise attenuation notably for the first three axial modes.
Show PACS
43.40.At Experimental and theoretical studies of vibrating systems
43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles

Propagation of elastic waves in a fluid-loaded anisotropic functionally graded waveguide: Application to ultrasound characterization

Cécile Baron and Salah Naili

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1307-1317 (2010); (11 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Non-destructive evaluation of heterogeneous materials is of major interest not only in industrial but also in biomedical fields. In this work, the studied structure is a three-layered one: A laterally heterogeneous anisotropic solid layer is sandwiched between two acoustic fluids. An original method is proposed to solve the wave equation in such a structure without using a multilayered model for the plate. This method is based on an analytical solution, the matricant, explicitly expressed under the Peano series expansion form. This approach is validated for the study of a fluid-loaded anisotropic and homogeneous plane waveguide with two different fluids on each side. Then, original results are given on the propagation of elastic waves in an asymmetrically fluid-loaded waveguide with laterally varying properties. This configuration notably corresponds to the axial transmission technique to the ultrasound characterization of cortical bone in vivo.
Show PACS
43.40.Dx Vibrations of membranes and plates
43.20.Mv Waveguides, wave propagation in tubes and ducts

Convolutional perfectly matched layer for elastic second-order wave equation

YiFeng Li and Olivier Bou Matar

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1318-1327 (2010); (10 pages) | Cited 5 times

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this work, a method is presented to extend the convolutional perfectly matched layer (C-PML) to simulate acoustic wave propagation in elastic media with a second-order equation formulation. This non-physical layer is used at the computational edge of a finite element method algorithm in frequency domain, and a pseudo-spectral algorithm in time domain, as an absorbing boundary condition (ABC) to truncate unbounded media. Numerical results show that the C-PML ABC attenuates the outgoing surface waves more effectively than classical PML ABC as proposed by Berenger [ J. Comput. Phys. 114, 195–200 (1994) ] for electromagnetic waves in the case of oblique incidence, where the PML method suffers from large spurious reflections. Moreover, a modification of the proposed C-PML formulation is also discussed in order to stabilize the absorbing layer in anisotropic solids where numerical instabilities can appear.
Show PACS
43.40.Fz Acoustic scattering by elastic structures
43.20.Bi Mathematical theory of wave propagation
43.20.Fn Scattering of acoustic waves
43.20.Gp Reflection, refraction, diffraction, interference, and scattering of elastic and poroelastic waves

Classification of a cylindrical target buried in a thin sand-water mixture using acoustic spectra

Dominique Décultot, Romain Liétard, and Gérard Maze

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1328-1334 (2010); (7 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A number of papers have shown that it is possible to characterize an air-filled cylindrical shell immersed in water using data obtained from a backscattering spectrum. The scattered impulse time signal is constituted of echoes linked to the reradiation of waves circumnavigating around the cylindrical target. In the first part of this work, the scattered signal is calculated and then measured under conditions where the cylindrical shell is immersed in water. In the second part, the cylindrical shell is buried in a thin sand-water mixture. It is insonified perpendicularly to its axis and perpendicularly to the water mixture interface. The scattered impulse time signal is recorded and processed using a Fourier transform algorithm to obtain a resonance spectrum. Among all the resonances that are established in the explored frequency band, only those related to the circumferential S0 wave are observed on the resonance spectrum of a cylindrical shell buried in the sand-water mixture. Resonances of the circumferential A wave also called A0− wave seem to have vanished. The resonance spectrum obtained by the Method of Isolation and Identification of Resonances (MIIR) reveals that it is possible to detect and classify an object buried in thin sand-water mixture in laboratory conditions.
Show PACS
43.40.Fz Acoustic scattering by elastic structures
43.20.Tb Interaction of vibrating structures with surrounding medium
43.20.Fn Scattering of acoustic waves
43.30.Jx Radiation from objects vibrating under water, acoustic and mechanical impedance

The effect of buildings on acoustic pulse propagation in an urban environment

Donald G. Albert and Lanbo Liu

J. Acoust. Soc. Am. Volume 127, Issue 3, pp. 1335-1346 (2010); (12 pages) | Cited 3 times

Online Publication Date: 23 Mar 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Experimental measurements were conducted using acoustic pulse sources in a full-scale artificial village to investigate the reverberation, scattering, and diffraction produced as acoustic waves interact with buildings. These measurements show that a simple acoustic source pulse is transformed into a complex signature when propagating through this environment, and that diffraction acts as a low-pass filter on the acoustic pulse. Sensors located in non-line-of-sight (NLOS) positions usually recorded lower positive pressure maxima than sensors in line-of-sight positions. Often, the first arrival on a NLOS sensor located around a corner was not the largest arrival, as later reflection arrivals that traveled longer distances without diffraction had higher amplitudes. The waveforms are of such complexity that human listeners have difficulty identifying replays of the signatures generated by a single pulse, and the usual methods of source location based on the direction of arrivals may fail in many cases. Theoretical calculations were performed using a two-dimensional finite difference time domain (FDTD) method and compared to the measurements. The predicted peak positive pressure agreed well with the measured amplitudes for all but two sensor locations directly behind buildings, where the omission of rooftop ray paths caused the discrepancy. The FDTD method also produced good agreement with many of the measured waveform characteristics.
Show PACS
43.40.Fz Acoustic scattering by elastic structures
43.28.En Interaction of sound with ground surfaces, ground cover and topography, acoustic impedance of outdoor surfaces
43.28.Js Numerical models for outdoor propagation
43.20.El Reflection, refraction, diffraction of acoustic waves
Page 1 of 59 Pages Next Page | Jump to Page
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close