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Jun 1984

Volume 75, Issue 6, pp. 1673-1935

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Thin shell theories and acoustic wave scattering by infinitely long cylindrical shells of arbitrary cross section

S. Baskar, V. V. Varadan, and V. K. Varadan

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1673-1679 (1984); (7 pages) | Cited 3 times

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The scattering of acoustic waves by an infinitely long cylindrical shell immersed in a fluid is analyzed. A new approach has been proposed using thin shell theory incorporating the impedance of the shell in the T‐matrix formulation. Numerical results are presented for the farfield backscattering amplitude as a function of frequency. Calculations were made for infinitely long circular and elliptic cylindrical shells immersed in water for various shell thicknesses for waves incident at an arbitrary angle in the plane normal to the axis of the cylinder. The impedance resulting from the use of various shell theory approximations for circular cylindrical shells is presented. Love–Timoshenko and Flügge–Byrne–Lurye theories for circular cylindrical shells have been compared with the full elasticity solution using the separation of variables approach. Comments have been made regarding the range of applicability of various shell theories.
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43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation
43.40.Ey Vibrations of shells

Acoustic spectrogram and complex‐frequency poles of a resonantly excited elastic tube

G. C. Gaunaurd and D. Brill

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1680-1693 (1984); (14 pages) | Cited 9 times

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We present a study of the resonance scattering undergone by an air‐filled hollow elastic cylinder excited by an incident plane acoustic wave. We construct the boundary value problem, obtain its classical solution, the solution based on the Resonance Scattering Theory (RST), and generate a variety of useful computed results, some of which are later compared to experimental observations recently performed in France. We present highly accurate expressions for the phase and group velocities and for the phase and group attenuations of the first few surface waves circumnavigating (the extreme cases) of rigid and soft cylinders, and display these dispersion plots in all instances. We analyze the modal backgrounds and modal resonances of the shell, display them in a wide spectral band, determine the SEM‐type pole‐position diagram in the complex k1a plane, and obtain and display the background‐suppressed cross section of the tube. This result serves to generate the acoustic spectrogram of the shell as well as to show the excellent agreement of this theoretical prediction with the experimental observations carried on in France. We analyze cross‐sectional poles and cross‐sectional dips, and reduce many of the present shell results to particular cases for impenetrable cylinders and solid elastic cylinders. For these latter ones, we obtain the dispersion plots for the phase and group velocities of the internal surface waves revolving around them. We determine expressions for the nearfield shell cross sections at different ranges, and compare them to the usual farfield results. We determine the sound pressure levels transmitted into the shell’s interior, and exhibit the controlling role the tube resonances have on the isobaric contours. We display extensive computerized calculations to illustrate all these points. Comparisons with experimental observations are shown to be quite favorable, particularly for the background‐suppressed shell cross section, and for its acoustic spectrogram.
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43.20.Fn Scattering of acoustic waves
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Bi Mathematical theory of wave propagation
43.20.Ks Standing waves, resonance, normal modes

Diffraction of elastic waves by a sub‐surface crack (in‐plane motion)

J. H. M. T. van der Hijden and F. L. Neerhoff

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1694-1704 (1984); (11 pages) | Cited 2 times

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A rigorous theory of the diffraction of time‐harmonic elastic waves by an arbitrarily oriented, cylindrical, stress‐free crack of finite width embedded in a semi‐infinite elastic medium is presented. The incident wave is taken to be either a P wave, an SV wave, or a Rayleigh wave. The resulting boundary‐value problems for the unknown jump in the particle displacement across the crack are solved by employing the integral‐equation method in combination with the Galerkin method. Numerical results are presented in the form of scattering cross sections, normalized power scattering characteristics, dynamic stress intensity factors, and Rayleigh wave transmission and reflection coefficients, for a range of geometrical parameters.
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43.20.Fn Scattering of acoustic waves
62.30.+d Mechanical and elastic waves; vibrations
43.20.Bi Mathematical theory of wave propagation
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products

Rough surface scattering via the smoothing method

John G. Watson and Joseph B. Keller

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1705-1708 (1984); (4 pages) | Cited 7 times

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The smoothing method is used to find the first two moments, i.e., the mean and the two‐point two‐time correlation function, of the field scattered by a rough surface. The results are expressed in terms of a reflection coefficient and a differential scattering coefficient. They are compared with those found by several other methods.
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43.20.Fn Scattering of acoustic waves

Generation of acoustic waves by an impulsive point source in a fluid/solid configuration with a plane boundary

Adrianus T. de Hoop and J. H. M. T. van der Hijden

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1709-1715 (1984); (7 pages) | Cited 12 times

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The space–time acoustic wave motion generated by an impulsive monopole point source in a fluid/solid configuration with a plane boundary is calculated with the aid of the modified Cagniard technique. The source is located in the fluid, and numerical results are presented for the reflected‐wave acoustic pressure, especially in those regions of space where head‐wave contributions occur. There is a marked difference in time response in the different regimes that exist for the wave speed in the fluid in relation to the different wave speeds (compressional, shear, Rayleigh) in the solid. These differences are of importance to the situation where the reflected wave in the fluid is used to determine experimentally the elastic properties of the solid.
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43.20.Px Transient radiation and scattering
43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation

The impulse response of a focused source with an arbitrary axisymmetric surface velocity distribution

W. A. Verhoef, M. J. T. M. Cloostermans, and J. M. Thijssen

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1716-1721 (1984); (6 pages) | Cited 7 times

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An analytical expression for the impulse response of a focused transducer with an axisymmetric nonuniform surface velocity distribution is derived using a finite polynomial expansion of the velocity distribution function. A computing scheme is presented for the numerical calculation of the transient pressure at an observation point in front of the transducer. The effect of various nonuniform velocity distributions on the characteristics of the pressure field of a medium focused transducer is shown with grey‐scale pictures of calculated continuous‐wave and pulsed pressure distributions.
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43.20.Px Transient radiation and scattering
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.38.Ar Transducing principles, materials, and structures: general

Theoretical and experimental study of the contribution of radial modes to the pulsed ultrasonic field radiated by a thick piezoelectric disk

J. C. Baboux, F. Lakestani, and M. Perdrix

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1722-1731 (1984); (10 pages) | Cited 2 times

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A theoretical model is presented for evaluating the transient field radiated on the axis of a thick piezoelectric disk, by vibrations propagating radially on the circular transmitting face, from its rim towards its center. We had previously considered these vibrations to account for two unexpected signals (denoted S1 and S2), which were observed by measuring, with a miniature probe, the field produced in a liquid by a barium titanate disk (25 mm in diameter, 20 mm in thickness). These signals S1 and S2, not described by the well‐known piston model, are due to vibrations which propagate radially on the disk face at two different speeds (5.0 × 103 and 2.6 × 103 m/s); we have called them radial vibrations as a simplification. Here, a simulation is undertaken to explain the complex changes observed in the amplitude and in the shape of signals S1 and S2, when the distance from the disk face varies. In this theoretical approach, it is assumed that the disturbance initially located on the rim of the disk face remains unchanged during its propagation along a disk radius. With these simplifying hypotheses, different analytical expressions for the impulse velocity potential ϕi (t) are obtained, each of them valid in a limited area of the disk axis. The resulting transient pressure p(t) is then used to predict the signals detected by the miniature probe. For this simulation we have taken account of the time dependence of the initial motion, together with the response of the measuring device. Several plots are chosen to illustrate the influence of different parameters such as the speed of the radial vibration or the duration of the input excitation signal. Finally, the comparison with the experimental results proves the efficiency of our model to describe the main characteristics of the signals produced by the radial vibrations: their contribution is important only close to the disk face and the position of a particular point on axis, called focus, is correctly predicted. Different possible improvements in the modeling are also discussed.
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43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.38.Fx Piezoelectric and ferroelectric transducers
43.20.Bi Mathematical theory of wave propagation
43.20.Px Transient radiation and scattering

The forward and backward projection of acoustic fields from axisymmetric ultrasonic radiators using impulse response and Hankel transform techniques

Anthony F. Medeiros and Peter R. Stepanishen

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1732-1740 (1984); (9 pages) | Cited 4 times

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A generalized impulse response formulation to evaluate the harmonic pressure field of ultrasonic planar vibrators having axisymmetric nonuniform surface velocity distributions is presented. The harmonic pressure is expressed as a Fourier transform of a generalized impulse response which is a function of the spatially nonuniform velocity of the vibrator. A backward projection method is then developed to reconstruct the normal surface velocity of axisymmetric vibrators from harmonic field pressures using an angular spectrum or Hankel transform formulation. The numerical accuracy of the backward projection technique is evaluated using the impulse response formulation to evaluate the pressure fields for several velocity distributions on disk vibrators. Experiments were performed to reconstruct the velocity distributions over the surface of a uniformly driven piezoelectric ceramic disk and ceramic ring using farfield measurements of the complex pressure. The experimental results were in good agreement with theoretical results based on the electrode patterns of the transducers.
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43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.20.Bi Mathematical theory of wave propagation

Acoustoelasticity in transversely isotropic materials

George C. Johnson and G. Thomas Mase

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1741-1747 (1984); (7 pages)

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The acoustoelastic response of a transversely isotropic body loaded in plane stress is computed for arbitrarily severe anisotropy. Relations for the propagation speeds of longitudinal and shear waves propagating normal to the plane of stress are given as functions of the stress. The shear wave results are combined to obtain expressions for the polarization direction, which in general differs from the principal directions of stress or strain, and the magnitude of the ultrasonic birefringence as given by the difference in transit time per unit length of the two shear waves. Similar expressions derived previously for slightly anisotropic bodies are recalled and are compared to the present results. It is shown that the earlier results are special cases of the more general model discussed here and a numerical investigation of the acoustoelastic response of several materials indicates that the assumptions leading to these more restricted models may not be valid, even in materials which at first glance appear to be slightly anisotropic.
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43.25.-x Nonlinear acoustics
62.30.+d Mechanical and elastic waves; vibrations

Intensity in stratified random media

R. Mazar and M. J. Beran

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1748-1759 (1984); (12 pages) | Cited 1 time

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Using a three‐scale expansion, we solved the equation governing the propagation of the coherence function in a random medium with a mean index of refraction profile. An expression for the intensity distribution near a caustic was obtained including both diffraction and scattering effects. The expression may be readily evaluated in the absence of scattering and in the case of weak or strong scattering. Numerical examples are presented.
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43.30.Es Velocity, attenuation, refraction, and diffraction in water, Doppler effect
43.30.Ft Volume scattering
43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation

Long‐range Pacific acoustic multipath identification

John Northrop and Richard C. Shockley

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1760-1765 (1984); (6 pages)

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Acoustic signals from three long‐range (500–700 km) transmission paths in the Northeast Pacific were examined for multipath structures. Sound propagation along each path encountered both different sound‐speed provinces and unique bathymetry which, together with the range differences, caused characteristic pulse arrival patterns at each hydrophone site. The receivers were all on a sloping bottom at depths between 1200 and 1400 m and the source depth was at 450 m in deep water. Ray‐path arrivals were modeled using impulse, a new ray‐theoretical impulse response code written by one of us (RCS). This code uses piecewise continuous cubic polynomials to fit the sound‐speed profile and bathymetric profile, and Runge–Kutta methods to solve the ray equation of motion. It allows arbitrary ray density in launch angle, and identifies eigenrays by searching for rays whose depths bracket the receiver and which were adjacent at the source. Using this procedure, we were able to identify most of the major pulse arrivals observed at each of the recording sites.
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43.30.Es Velocity, attenuation, refraction, and diffraction in water, Doppler effect
43.20.Dk Ray acoustics
43.30.Cq Ray propagation of sound in water
92.10.Vz Underwater sound

High‐temperature acoustic bond compatible with fluoride fluorites. II. Transverse ultrasonic measurements in barium fluoride

M. O. Manasreh and D. O. Pederson

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1766-1769 (1984); (4 pages)

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The ultrasonic pulse‐echo technique method has been used to measure high‐temperature acoustic wave velocities and ultrasonic attenuation in [110] oriented, single‐crystal, barium fluoride. DuPont 9770 silver–platinum paste was used as an effective acoustic bond for transverse ultrasonic velocities for the first time. The velocity measurements for two different shear wave polarization directions have been made over a temperature range of 300 °K to approximately 1200 °K allowing calculations of the elastic constants C44 and (C11–C12) to be made. Ultrasonic attenuation measurements for one polarization were also made. Both (C11–C12) and the attenuation measurements begin anomalous behavior just below the diffuse solid electrolyte transition in barium fluoride at 1235 °K.
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43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
62.30.+d Mechanical and elastic waves; vibrations

The nonlinear free vibration of a damped elastic string

Colin Gough

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1770-1776 (1984); (7 pages) | Cited 3 times

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A theoretical analysis of the large‐amplitude free vibration of a damped elastic string shows that the perturbation in vibrational frequency and the precession of any orbital motion of the string about its equilibrium position resulting from nonlinearity is simply related to the mean‐square radius and area of the orbital motion. A computer simulation of the coupled nonlinear equations of motion and measurements made on a loosely stretched string confirm our theoretical predictions, which differ from those of an earlier analysis by Anand [J. Acoust. Soc. Am. 45, 1089–1096 (1969)]. The significance of nonlinear string vibration is considered for musical instruments.
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43.40.Cw Vibrations of strings, rods, and beams
43.40.Ga Nonlinear vibration
43.40.Tm Vibration isolators, attenuators, and dampers

Reflection characteristics of longitudinal waves in a semi‐infinite cylindrical rod connected to an infinite elastic stratum

Hiroshi Wada

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1777-1782 (1984); (6 pages)

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Reflection characteristics of longitudinal strain waves in a semi‐infinite cylindrical rod connected to an infinite elastic stratum are investigated analytically. Applying three‐dimensional elasticity theory to the stratum and making use of Laplace transformations with respect to time and numerical inverse Laplace transformations, the time histories for the longitudinal strain at an arbitrary point of the rod are presented. Numerical results obtained from three‐dimensional elasticity theory are compared with numerical results obtained from Mindlin plate theory, classical plate theory, and experimental results. When the stratum is stiff compared with the rod, the reflected waves from the interface between the stratum and the rod, which are obtained from the three theories, i.e., three‐dimensional elasticity theory, Mindlin plate theory, and classical plate theory, are nearly coincident with one another. On the contrary, when the stratum is flexible compared with the rod, they are different from one another. The stratum may be considered as a half‐space for a stratum thickness ratio (stratum thickness/rod radius) κ≥8.0 in the case of the stiff stratum, while it may be considered as a half‐space for κ≥15.0 in the case of the flexible stratum.
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43.40.Cw Vibrations of strings, rods, and beams
43.20.Bi Mathematical theory of wave propagation
43.20.Fn Scattering of acoustic waves

ESPI—The ultimate holographic tool for vibration analysis?

Ole J. Løkberg

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1783-1791 (1984); (9 pages) | Cited 7 times

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Holographic interferometry opened new worlds of research by making possible accurate, global mapping of small dynamic surface displacements in a two‐step process. A technique, called Electronic Speckle Pattern Interferometry or ESPI, has been developed in various forms to provide similar results instantly. ESPI’s principal capabilities, and some practical applications in industry, biomedicine, and acoustical research are described in an overview in the hope of encouraging its use by researchers who were deterred by the relatively cumbersome process of holography. In various forms, ESPI is shown to be capable of measuring phase and amplitude of dynamic displacements between 0.01 nm and 10 μm over an area of up to 1 m2.
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43.40.Yq Instrumentation and techniques for tests and measurement relating to shock and vibration, including vibration pickups, indicators, and generators, mechanical impedance
07.60.Ly Interferometers
42.40.My Applications
46.80.+j Measurement methods and techniques in continuum mechanics of solids
43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography

The cruciform dynamic vibration absorber

J. C. Snowdon, A. A. Wolfe, and R. L. Kerlin

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1792-1799 (1984); (8 pages) | Cited 2 times

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The cruciform dynamic absorber comprises two free–free beams that are mass loaded at their free ends and that are joined centrally at right angles at a point at which they are attached to the vibrating item or structure of concern. Both a lumped simple system and distributed mechanical systems such as beams and clamped circular plates are considered. The damping of the absorber beams and of the lumped and distributed mechanical systems is assumed throughout to be of the solid type. The branches (arms) of the cruciform dynamic absorber are generally tuned to the fundamental and second or third resonances of the distributed mechanical systems considered. Sometimes, one branch is tuned to the fundamental resonance of the distributed mechanical system concerned while the other branch, with essentially zero damping, is tuned off resonance, for example, to the frequency of a troublesome machinery discrete, thereby generating a pronounced trough in the transmissibility curve with a compensating transmissibility peak at a slightly higher frequency that is not necessarily of predominant magnitude.
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43.40.Tm Vibration isolators, attenuators, and dampers
43.40.Cw Vibrations of strings, rods, and beams

Temporal averaging of subjective magnitude and proposed rating scale for fluctuating noise

Kozo Hiramatsu, Koichi Takagi, and Takeo Yamamoto

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1800-1806 (1984); (7 pages)

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A method for predicting the effective sound level (ESL) is proposed in this paper. The effective sound level is the sound level of a steady noise which produces the same subjective magnitude as a fluctuating noise and may be measured as the point of subjective equality by means of psychometric methods. The proposed method gives the predicted value of ESL which is denoted as Leff, based on an assumption of integration and averaging of subjective magnitude. It has been shown that Leff can be expressed by an equation which contains the probability density function of the level distribution and two empirical parameters, the values of exponents for sound pressure and duration in the psychophysical function. The practical significance of the descriptor Leff was discussed in terms of the definition of the number of events. High correlation between Leff and the subjects’ response was found.
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43.50.Ba Noisiness: rating methods and criteria
43.50.Qp Effects of noise on man and society
43.20.Bi Mathematical theory of wave propagation

Model studies of barrier performance in the presence of ground surfaces. Part I—Thin, perfectly reflecting barriers

D. A. Hutchins, H. W. Jones, and L. T. Russell

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1807-1816 (1984); (10 pages) | Cited 2 times

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A scale model study is presented of the performance of thin, perfectly reflecting semi‐infinite barriers in the presence of both asphalt and grass‐covered surfaces. The barrier insertion loss is shown to be strongly dependent on the type of ground on either side of the barrier. Observed behavior is explained by a study of the interference phenomena occurring in both the barrier’s presence and its absence.
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43.50.Gf Noise control at source: redesign, application of absorptive materials and reactive elements, mufflers, noise silencers, noise barriers, and attenuators, etc.
43.28.Fp Outdoor sound propagation through a stationary atmosphere, meteorological factors

Model studies of barrier performance in the presence of ground surfaces. Part II—Different shapes

D. A. Hutchins, H. W. Jones, and L. T. Russell

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1817-1826 (1984); (10 pages) | Cited 3 times

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Modeling experiments are reported which have investigated the frequency dependence of barrier insertion loss for various noise barrier designs. The effect of ground surfaces has been studied, treating both grass‐covered ground and asphalt. Results show that interference effects are an important feature of observed behavior. Use is made of this knowledge in the design and testing of new barrier designs, which deliberately introduce a beneficial destructive interference phenomenon to increase insertion losses over well‐defined ranges of frequency.
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43.50.Gf Noise control at source: redesign, application of absorptive materials and reactive elements, mufflers, noise silencers, noise barriers, and attenuators, etc.
43.28.Fp Outdoor sound propagation through a stationary atmosphere, meteorological factors

Extension of the image model to arbitrary polyhedra

Jeffrey Borish

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1827-1836 (1984); (10 pages) | Cited 18 times

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In this paper, the image model is extended to arbitrary polyhedra with any number of sides. This generalization makes it possible to model real concert halls much more accurately. The image positions computed by the method can be reduced to the directional impulse response in order to create audible simulations of the concert hall. Also, the image model can provide insight into the fundamental acoustical properties of different concert hall geometries. For example, the extended image model demonstrates that rectangular halls have an advantage over fan‐shaped halls with regard to spatial impression. We also show why the image model has fundamental advantages over another popular modeling technique, ray tracing.
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43.55.Ka Computer simulation of acoustics in enclosures, modeling

Hybrid time‐delay/phase‐shift digital beamforming for uniform collinear arrays

Robert A. Gabel and Richard R. Kurth

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1837-1847 (1984); (11 pages)

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Digital phase‐shift beamforming of narrow‐band signals from uniform collinear hydrophone arrays may be accomplished by computationally efficient discrete Fourier transform (DFT) algorithms. However, phase‐shift beamforming is a valid approximation to delay‐and‐sum steering only over a restricted bandwidth limited by array aperture and steering angle. A multiple‐beam digital beamforming technique is described which is a hybrid of phase‐shift and time‐delay operations designed for bandwidths in excess of the phase‐shift limit. The beamformer employs fast DFTs for phase‐shifting, organized according to a particular decomposition of the array into subarrays, plus a limited amount of delay steering by interpolation. The result is a substantial reduction in the number of digital arithmetic operations compared with the alternative of delay‐and‐sum steering by interpolation. The design principles of the hybrid beamformer are described and an example presented to illustrate its computational advantages.
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43.60.Gk Space-time signal processing, other than matched field processing
43.30.Wi Passive sonar systems and algorithms, matched field processing in underwater acoustics

The functional analysis of auditory discrimination

J. M. Harrison

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1848-1854 (1984); (7 pages)

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Mammals have evolved the ability to acquire auditory discriminations. The characteristics of this discriminative ability presumably fit the natural conditions under which discriminations are normally acquired. The purpose of this paper is to review experiments which were directed at showing that auditory discriminations are most rapidly acquired when natural features are incorporated into the experiments. The experiments were also directed at discovering the underlying characteristics of the discriminative ability. When animals were trained to discriminate the position of a sound source in which natural features were incorporated into the experiment, the discrimination was acquired in one trial. Manipulation of the natural features suggested that one trial acquisition depends upon the following. (1) Stimulus novelty; the effect of reinforcement is stronger in the presence of novel than familiar stimuli. (2) Specific behavioral effect of reinforcement; the effect of reinforcing a response in the presence of a novel auditory stimulus is to increase the strength of approaching and manipulating the sound source.
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43.66.Gf Detection and discrimination of sound by animals
43.66.Ba Models and theories of auditory processes
43.66.Qp Localization of sound sources

Comment on ‘‘Measurement of pitch in speech: An implementation of Goldstein’s theory of pitch perception’’ [J. Acoust. Soc. Am. 71, 1568 (1982)]

Jüri Allik, Meelis Mihkla, and Jaan Ross

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1855-1857 (1984); (3 pages)

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The pitch detection algorithm proposed by Duifhuis, Willems, and Sluyter [J. Acoust. Soc. Am. 71, 1568–1580 (1982)] can be made more than 20 times faster by replacing the harmonic sieve procedure by the approximate common denominator procedure, the results differing only slightly.
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43.66.Hg Pitch
43.66.Ba Models and theories of auditory processes
43.72.Ar Speech analysis and analysis techniques; parametric representation of speech
43.70.Jt Instrumentation and methodology for speech production research

Underlying dimensions and individual differences in auditory, visual, and auditory–visual vowel perception by hearing‐impaired children

P. A. Busby, Y. C. Tong, and G. M. Clark

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1858-1865 (1984); (8 pages)

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Vowel perception studies were conducted on a group of four adolescent children with congenital profound sensorineural hearing impairments in the three conditions of audition alone, vision alone, and audition plus vision. Data were analyzed using the alscal multidimensional scaling procedure to identify the underlying dimensions and individual differences in dimension emphasis. The three dimensions obtained from the analysis of data for the audition alone condition were interpreted as the parameters of first and second formant frequencies, and vowel length. The one dimension for the vision alone condition was interpreted as the parameter of the width of the internal lip opening. The three dimensions for the audition plus vision condition were interpreted as the parameters of first formant frequency, vowel length, and the width of the internal lip opening. Subject variations in parameter preferences were observed for the audition alone and audition plus vision conditions but not for the vision alone condition.
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43.71.Ky Speech perception by the hearing impaired
43.66.Sr Deafness, audiometry, aging effects
43.71.Rt Sensory mechanisms in speech perception

Phonemic and phonetic factors in adult cross‐language speech perception

Janet F. Werker and Richard C. Tees

J. Acoust. Soc. Am. Volume 75, Issue 6, pp. 1866-1878 (1984); (13 pages) | Cited 10 times

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Previous research has indicated that young infants can discriminate speech sounds across phonetic boundaries regardless of specific relevant experience, and that there is a modification in this ability during ontogeny such that adults often have difficulty discriminating phonetic contrasts which are not used contrastively in their native language. This pattern of findings has often been interpreted as suggesting that humans are endowed with innate auditory sensitivities which enable them to discriminate speech sounds according to universal phonetic boundaries and that there is a decline or loss in this ability after being exposed to a language which contrasts only a subset of those distinctions. The present experiments were designed to determine whether this modification represents a loss of sensorineural response capabilities or whether it shows a shift in attentional focus and/or processing strategies. In experiment 1, adult English‐speaking subjects were tested on their ability to discriminate two non‐English speech contrasts in a category‐change discrimination task after first being predisposed to adopt one of four perceptual sets. In experiments 2, 3, and 4 subjects were tested in an AX (same/different) procedure, and the effects of both limited training and duration of the interstimulus interval were assessed. Results suggest that the previously observed ontogenetic modification in the perception of non‐native phonetic contrasts involves a change in processing strategies rather than a sensorineural loss. Adult listeners can discriminate sounds across non‐native phonetic categories in some testing conditions, but are not able to use that ability in testing conditions which have demands similar to those required in natural language processing.
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43.71.Hw Cross-language perception of speech
43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation
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