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Jul 1977

Volume 62, Issue 1, pp. 1-218

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Waves in thin‐walled, nonuniform, perfectly elastic tubes containing incompressible inviscid fluid

D. W. Barclay, T. Bryant Moodie, and J. B. Haddow

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 1-7 (1977); (7 pages) | Cited 2 times

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Wave propagation in a semi‐infinite, nonuniform, elastic thin‐walled tube filled with incompressible, inviscid fluid is considered. A one‐dimensional problem, with the tube and fluid initially at rest and a pressure disturbance applied at the end, is solved for different axial variations of the tube properties. Formal asymptotic techniques are applied to the linearized partial differential equation governing the pressure and simple progressing wave and high‐frequency solutions are obtained for Heaviside and oscillatory‐pressure boundary conditions, respectively. These asymptotic series solutions terminate for certain parameter variations to give exact solutions for the pressure. Numerical results are presented and some interesting observations concerning the accuracy of the formal results are made.
Show PACS
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Bi Mathematical theory of wave propagation
43.40.Cw Vibrations of strings, rods, and beams

Acoustic coupling between two finite‐sized spherical sources

William Thompson, Jr.

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 8-11 (1977); (4 pages) | Cited 1 time

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The problem of acoustic radiation from a pair of spherical sources vibrating with time‐harmonic velocity distributions which are constant in strength and axisymmetric about the same axis is considered. In particular, the modification of the radiation load on one source due to the presence of the other is evaluated. Numerical results are presented for the four cases of equisize sources which are either in phase or 180° out of phase from one another and vibrating in either the pulsating (monopole) or oscillating (dipole) modes. For sources which are small relative to the wavelength, the results are essentially as predicted by previous analyses of point sources, with the exception of the in‐phase dipoles where, for small wavelength separations between the sources, the radiation resistance of one dipole is not doubled by the presence of the other. As the wavelength size of a source is increased, the near presence of another source affects the reactive component of the radiation loading more than the resistive component.
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43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods

Stable arrays of resonant bubbles in a 1‐MHz standing‐wave acoustic field

Douglas L. Miller

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 12-19 (1977); (8 pages) | Cited 1 time

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As observed microscopically, bubbles in a standing‐wave acoustic field move to the pressure nulls and oscillate, in elliptical orbits, about a common axis. The orbits of individual bubbles are equally spaced about 100 μm apart along the axis, forming a linear array. These arrays form in tap water for peak pressure amplitudes of 10–20 bar, but persist at levels as low as 1.5 bar. The 7‐μm diameter of the bubbles is approximately the theoretical size for resonant air bubbles in water driven at the 986 kHz frequency of the field. The radius of the orbits is approximately inversely proportional to the pressure gradient at the pressure null, with proportionality constant 0.25 bar. In a simplified model of the orbit phenomenon the expected proportionality constant is given by (2)1/2ps, where ps is the threshold pressure amplitude for rectified diffusion and has the value 0.18 bar. Calculations of ps, based on current theories for rectified diffusion, are in substantial agreement with the this value. The period of the orbital motion is about 1 msec for an orbit radius B of 35 μm, and increases to about 6.5 msec for B=100 μm. Two adjacent bubbles are synchronized in their orbits approximately 90° out of phase, as required for stability of the arrays under Bjerknes forces.
Show PACS
43.25.Yw Nonlinear acoustics of bubbly liquids
43.35.Ei Acoustic cavitation in liquids

Measurements of the acoustic radiation pressure on a sphere in a standing wave field

Isadore Rudnick

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 20-22 (1977); (3 pages) | Cited 3 times

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Show Abstract
The force on a small sphere due to radiation pressure in a plane wave field was measured and was found to be in excellent quantitative agreement with L. V. King’s predictions [Proc. R. Soc. London Ser. A 147, 212 (1934)]. Reynolds numbers as high as 2500 were used.
Show PACS
43.25.Qp Radiation pressure
43.20.Ks Standing waves, resonance, normal modes
43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves

Nonlinear mode coupling of elastic waves

Nobumasa Sugimoto and Masahiko Hirao

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 23-32 (1977); (10 pages) | Cited 1 time

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The theory of nonlinear elasticity is applied to a study of mode coupling of elastic waves at a particular frequency, called the critical frequency, in a long circular wire. It is assumed that the wire is of homogeneous isotropic elastic material and that the nonlinearity of medium (the effects of higher‐order elasticity) is primary rather than that involved in the Lagrangian stress and strain tensors. The latter is suggested from the fact that the third‐order elastic constants are of larger order of magnitude than the Lamé constants. The method of multiple scales is employed to obtain a system of equations which describes the behavior of the amplitudes involved in the mode coupling. The analysis of the equations shows that nonlinear mode coupling can occur at the critical frequency and that, except at this frequency, the wave undergoes only a phase shift. Further, progressive wave solutions show that the two wave amplitudes can be expressed in terms of Jacobian elliptic functions, and energy exchange between two modes takes place. Under special conditions, these periodic solutions degenerate to the solitary or shocklike solutions.
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43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves
43.40.Ga Nonlinear vibration
43.25.Gf Standing waves; resonance

Harmonic generation of longitudinal elastic waves

R. B. Thompson and H. F. Tiersten

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 33-37 (1977); (5 pages) | Cited 5 times

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The propagation of the fundamental and harmonically generated longitudinal elastic waves is treated by means of an asymptotic iterative procedure directly in the governing nonlinear differential equation. Explicit results are obtained for the steady‐state, spatial growth of the second and third harmonic and the depletion of the input wave. As expected, the analysis indicates that the amplitude of the Nth harmonic depends on all the elastic constants up to order N+1. However, the forms for the amplitudes obtained in the asymptotic solution reveal that, for the known range of ratios of elastic constants of successively increasing order and propagation distances commonly encountered in harmonic generation experiments, only the quadratic nonlinearity, which depends on the second‐ and third‐order elastic constants, is required to accurately account for the experimental results. In addition, the amplitude dependence of the phase velocity of the fundamental longitudinal wave is determined.
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43.25.Ba Parameters of nonlinearity of the medium
43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves
43.40.Ga Nonlinear vibration

Numerical technique for computing the wide‐angle acoustic field in an ocean with range‐dependent velocity profiles

L. E. Estes and G. Fain

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 38-43 (1977); (6 pages) | Cited 1 time

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A numerical technique for the propagation of sound in the ocean where velocity is a function of both range and depth has been developed. The technique is not restricted to the narrow‐angle (parabolic) approximation and it reduces to an exact solution for a homogeneous media. The given field is transformed into a sum of plane waves via an FFT. This transformed field is propagated without approximation through a homogeneous space represented by an average wave number for that space. Updating the average wave number provides for Snell’s law bending in range. The variations from the average velocity are accounted for by summing deviations from the nominal phase to develop a group of direction‐sensitive phase correction masks. A weighted group of plane waves centered about each direction are inverse transformed for multiplication by the phase mask with the results summed. The choice of overlapping weights in the transformed space provides an approximate continuous phase correction mask for all directions. The functional relationship of range‐step size to frequency, angular spectrum, and velocity profiles are developed. Several results for a 1500‐m channel are shown.
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43.30.Bp Normal mode propagation of sound in water
43.30.Ft Volume scattering
43.20.Bi Mathematical theory of wave propagation

Backscattering spectra of preserved zooplankton

Charles F. Greenlaw

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 44-52 (1977); (9 pages) | Cited 8 times

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Measured backscattering spectra for preserved specimens of three zooplankters (copepod, euphausiid, sergestid shrimp) are compared to fluid sphere scattering models. Quantitative agreement is found at low ka for all species, however the copepod results are increasingly higher than predicted for ka≳1 and the euphausiid and sergestid shirmp are found to be directional scatterers. A fluid prolate spheroid model is proposed fo the latter species.
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43.30.Dr Hybrid and asymptotic propagation theories, related experiments
43.80.Cs Acoustical characteristics of biological media: molecular species, cellular level tissues
43.30.Gv Backscattering, echoes, and reverberation in water due to combinations of boundaries

Combined influence of spatially uniform currents and tidally varying sound speed on acoustic propogation in the deep ocean

K. G. Hamilton, W. L. Siegmann, and M. J. Jacobson

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 53-62 (1977); (10 pages) | Cited 1 time

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The effects of a combination of sound‐speed and current fluctuations on propagation of a cw signal in a deep‐ocean model are analyzed. The mean sound‐speed structure is assumed bilinear, and the channel boundaries are horizontal. The horizontally independent sound speed oscillates with a 12‐h period, while the spatially uniform currents consist of quasisteady and diurnally varying components. The total acoustic field for surface‐reflected–bottom‐reflected rays is investigated for dependence on time, source‐receiver separation, and environmental parameters. Multipath propagation is demonstrated for larger propagation ranges, for which case the number, depths, and occurrence times of amplitude fades are shown to be very sensitive to parameter changes. Where the total field is dominated by one ray, contributions from combined sound‐speed and current fluctuations to phase are investigated. In both cases, phase generally can be influenced by both sound‐speed and current fluctuations, but the former more effectively influence amplitude.
Show PACS
43.30.Bp Normal mode propagation of sound in water
43.20.Dk Ray acoustics
43.28.Py Interaction of fluid motion and sound, Doppler effect, and sound in flow ducts

Statistical analysis of ambient noise

W. J. Jobst and S. L. Adams

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 63-71 (1977); (9 pages)

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This paper presents an approach to the characterization of the low‐frequency ambient‐noise continuum. A tutorial presentation of several statistical tests is given, followed by the application of these tests to the characterization of narrow‐band low‐frequency ambient noise as a function of space, time, and frequency. Measurements of temporal stationarity, spatial homogeneity, and frequency homogeneity are presented.
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43.30.Nb Noise in water; generation mechanisms and characteristics of the field
43.60.Cg Statistical properties of signals and noise

Acoustic radiation from point excited rib‐reinforced plate

Gau F. Lin and Sabih I. Hayek

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 72-83 (1977); (12 pages) | Cited 5 times

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An analytic solution for the acoustic radiation from a rib‐reinforced infinite elastic plate which is excited by a point force located on the rib was obtained. The solution exhibits a new coincidence angle, where the radiated pressure peaks, which depends on the relative stiffness and mass of the attached beam. An expression for the radiated power was also obtained which shows the general reduction of radiated power explicitly as a function of the mass and stiffness of the attached beam. Approximate formulas for the complex interaction between the beam and the plate were developed for frequencies above and below the coincidence frequency. Approximate expressions for the radiated power were obtained from simplified physical models.
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43.30.Jx Radiation from objects vibrating under water, acoustic and mechanical impedance
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.40.Dx Vibrations of membranes and plates

Estimation of background ambient noise levels from the spectral analysis of time series with application to cw propagation‐loss measurements

Jack A. Shooter and Steven L. Watkins

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 84-90 (1977); (7 pages)

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An application of percentile measurements is presented as a method for estimating background ambient noise levels from spectral density functions. The advantage of a percentile method over an average method is that it allows an accurate measure of background noise containing a sine wave, that is essentially independent of the sine‐wave amplitude. This feature makes the percentile method very useful in the measurement of cw propagation loss, where it is frequently necessary to subtract an estimate of the background noise from a signal‐plus‐noise measurement, including the case when the noise contains sine waves close in frequency to the cw signal. A percentile‐level estimate may be easily used to calculate an average level estimate for chi‐square data and it is found that a percentile estimator is just as accurate and essentially just as stable as an average estimator. Theory based on chi‐square statistics and experimental data from the ambient sound field in the deep ocean are shown to be in good agreement.
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43.30.Cq Ray propagation of sound in water
43.35.Yb Ultrasonic instrumentation and measurement techniques

Low‐frequency technique for the underwater calibration of individual elements of a line hydrophone array

Joseph F. Zalesak and W. James Trott

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 91-101 (1977); (11 pages)

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A calibrator for use with long line hydrophones (seismic streamers) has been designed, constructed, and tested. Comparison calibrations may be obtained for individual elements or small groups of interconnected elements of a line hydrophone array in the frequency range of 20 to 3000 Hz. Absolute calibrations may be obtained in the frequency range of 20 to 100 Hz. The calibrator may be operated in either of two configurations. The first configuration has the calibrator submerged in a water trough. In the second configuration the calibrator, with the hydrophone inserted, forms a closed chamber through which water is continuously circulated during operation. A comparison between results obtained by using the calibrator, and independent measurements is presented. The theory of operation of the device, and of the sonic resistors used to reduce standing waves within the calibrator, is presented in the appendixes.
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43.30.Sf Acoustical detection of marine life; passive and active
43.30.Yj Transducers and transducer arrays for underwater sound; transducer calibration

New ultrasonic imaging system using a moving random phase mask and a stationary‐point receiver

Takuso Sato, Shusou Wadaka, and Junichi Ishii

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 102-107 (1977); (6 pages)

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A new ultrasonic imaging system and apparatus are proposed which use a moving random phase mask placed just behind a coherently illuminated object, and a stationary‐point receiver located in the farfield. The power spectrum of the received signal represents the shadow of an object on the receiver plane and hence gives the image of the object under suitable conditions. The second‐order correlation function of the received signal gives the exact image of the object provided a reference‐point source is located nearby. The system constructed includes a minicomputer for signal processing and real‐time imaging. Experimental results for one‐dimensional objects are presented. It is also demonstrated experimentally that the system has advantages over conventional coherent ultrasonic imaging systems when propagating through a turbulent medium.
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43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
43.60.Gk Space-time signal processing, other than matched field processing
43.30.Bp Normal mode propagation of sound in water
43.58.Ta Computers and computer programs in acoustics

Ultrasonic spectrum analysis for nondestructive testing of layered composite materials

W. R. Scott and P. F. Gordon

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 108-116 (1977); (9 pages) | Cited 3 times

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In this paper, a simple model is presented which predicts the ultrasonic frequency spectra for a broad class of layered composite materials having a finite number of laminas. This model predicts spectra for arrays of glass plates in water and these spectra are experimentally verified. Precisely regular spectra are predicted for single plates, while irregular spectra are predicted for all of the arrays studied. Results relating to nondestructive testing which have emerged from this investigation include methods for predicting spectra for layered composite materials and techniques for mapping small changes in the modulus and thickness of composite materials. Also discussed is the existence of forbidden frequency bands for which ultrasound transmission is strongly attenuated in thick layered composites.
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43.35.Ae Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in gases

Shallow surface‐wave simulator for the study of jet‐noise sources

W. H. Colwill and G. Reethof

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 117-124 (1977); (8 pages)

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See Also: Erratum

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A shallow liquid surface‐wave analogy to turbulence‐induced sound was utilized to investigate the mechanisms of noise generation and propagation in jets. Theoretical analysis was used to determine the wave‐power dependence on Mach number and to derive the relationship between wave and turbulence spectra. The experimental investigation utilized a 24 ft2 mercury ripple tank. The waves were produced by the turbulence in a mercury jet exhausting into the tank. The results substantiate the validity of the surface‐wave analogy as a jet‐noise simulator. Measurement of mean and turbulent velocity profiles proved that the jet development was similar to the theoretical plane‐free jet. Farfield measurements of wave power, directivity, and spectra compared favorably with the acoustic case. However, the wave spectra showed little of the higher‐frequency content found with the turbulence spectra. This difference was attributed to the vertical spatial integration of the turbulence‐source terms, which is not found in jet noise.
Show PACS
43.50.Nm Aerodynamic and jet noise
43.28.Ra Generation of sound by fluid flow, aerodynamic sound and turbulence

Maximum‐likelihood estimation of source parameters from time‐sampled outputs of a linear array

Ibrahim N. El‐Behery and Robert H. MacPhie

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 125-134 (1977); (10 pages)

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This paper considers the joint estimation of the bearing and strength parameters of a noise source, by a uniformly spaced array of sensors in the presence of self‐noise, assumed to be independent between any pair of sensors. Contrary to the analogue systems of processing (i.e., correlation and beamforming), the present scheme, which is based on the maximum‐likelihood (ML) principle, operates on a set of time samples representing the bandlimited output of the array’s elements. The system, as a result, does not require the assumption of long observation time normally used in other schemes and is easily implemented on a digital computer. The resulting ML estimator is not in theory a sufficient one. Nevertheless, when the estimator’s variance is compared with the Cramer–Rao lower bound, the estimator virtually attains its asymptotic sufficiency as the number of array elements exceeds a ’’threshold’’ which is a decreasing function of the signal‐to‐noise ratio (SNR) and the length of the observation time. Except when the SNR is very poor and the observation time is quite short, the ’’threshold’’ is found to be surprisingly small. It is also demonstrated, at least when the error in the bearing estimate is small, that the ML estimator is unbiased.
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43.60.Cg Statistical properties of signals and noise
43.30.Vh Active sonar systems
43.28.Tc Sound-in-air measurements, methods and instrumentation for location, navigation, altimetry, and sound ranging

Frequency selectivity of single auditory‐nerve fibers in response to broadband noise stimuli

Aage R. Møller

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 135-142 (1977); (8 pages) | Cited 6 times

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The tuning of single auditory nerve fibers in the rat in response to broadband noise was studied in a large sound intensity range. Pseudorandom noise was used as stimuli and the cross spectrum between a period histogram of the noise and a period of the noise was used as an approximation of the transfer function from sound to the modulation of the neural discharge rate. In units with a CF higher than 1000 Hz, the width of the cross spectra (at 10‐dB points) invariably increased as the stimulus intensity increased and the center frequency decreased. The few units studied with CF below 1000 Hz seemed to undergo somewhat less of a change in width. The cross correlograms of all fibers with a characteristic frequency (CF) below 5 kHz showed a damped oscillation the duration of which decreased as stimulus intensity was increased. The similarity between the nonlinearity shown here and that shown in measurements of basilar membrane motion using the Mössbauer effect is discussed.
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43.64.Pg Electrophysiology of the auditory nerve
43.64.Ri Evoked responses to sounds

Postnatal development in the acoustic system of the house mouse in the light of developing masked thresholds

G̈unter Ehret

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 143-148 (1977); (6 pages)

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Postnatal development of masked auditory thresholds in the house mouse Mus musculus were behaviorally measured from the 10th to the 24th day. An unconditioned stop reflex and an unconditioned pinna reflex to tones were used for threshold determinations. Masked threshold levels first decrease from day 10 to day 12, then increase or remain constant until day 14, and finally decrease until day 16–18, where the adult levels are reached. The results are in agreement with anatomical and electrophysiological data in the literature. It was concluded that in the developing acoustical system of the mouse two effects superimpose: peripheral completion and central maturation. The data can be interpreted such that the peripheral development which lasts until day 14 dominates between the 12th and 14th postnatal day, whereas development in the central nervous system influences thresholds between day 10 and day 16–18. The widths of critical masking bands are assumed to be constant during development and determined by peripheral mechanisms.
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43.66.Gf Detection and discrimination of sound by animals
43.66.Dc Masking
43.64.Bt Models and theories of the auditory system
43.66.Cb Loudness, absolute threshold

Psychophysical structure of eight complex underwater sounds

James H. Howard, Jr.

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 149-156 (1977); (8 pages) | Cited 1 time

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The potential usefulness of multidimensional scaling techniques in the perceptual analysis of ’’real world’’ underwater sounds was demonstrated. Nineteen observers (nine with musical training, ten without) used a five‐point scale to judge the similarity of all possible pairs of eight passive sonar recordings. The eight s signals were selected to represent a range of common natural and man‐made underwater sounds. These data were analyzed using the INDSCAL multidimensonal scaling model, revealing an interpretable two‐dimensional psychological space. One of the psychological dimensions was interpreted as reflecting the overall shape of the 1/3‐octave spectra of the eight signals, while the second was seen to reflect the prominence of a low‐frequency periodicity present in some signals. Individual observer analysis revealed substantial differences between the musically trained and musically inexperienced observers in the relative importance or salience of the two dimensions. The relation of these findings to earlier work was discussed.
Show PACS
43.66.Lj Perceptual effects of sound
43.66.Yw Instruments and methods related to hearing and its measurement
43.30.Bp Normal mode propagation of sound in water

Model for the interaural time differences in the azimuthal plane

George F. Kuhn

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 157-167 (1977); (11 pages) | Cited 43 times

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An objective study of the steady‐state interaural time difference (ITD) was performed on a manikin comprised of a head and torso. Data were taken for both a bare and clothed torso. The measured ITD’s correspond reasonably accurately at the low and the high frequencies to the computed theoretical values for a rigid sphere of an effective radius a. The theoretical ratio of the low‐frequency (<500 Hz) ITD to the high‐frequency (≳2000 Hz) ITD is 3/2. The measured ITD is a minimum between 1.4 and 1.6 kHz for angles of incidence, ϑinc, of sound between 15° and 60°. At both the low and the high frequencies the data can be expressed by universal curves when the ITD is normalized by (a/c0)  sinϑinc, where c0 is the speed of sound in air and ϑinc is the angle of incidence. Both the steady‐state ITD and the interaural sound‐pressure‐level difference (ILD) show differences between measurements made with the bare torso and those with a clothed torso. These objectives results support the subjective measurements of past experiments, which showed that in man there was no localization improvement below approximately 500 Hz, poor localization between 1000 and 2000 Hz, and a change in the localization cue around 1400 Hz from ITD to ILD.
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43.66.Qp Localization of sound sources
43.66.Nm Phase effects
43.66.Pn Binaural hearing

Temporal integration at the ’’threshold’’ of the acoustic reflex

Donald E. Morgan, Samuel Gilman, and Donald D. Dirks

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 168-176 (1977); (9 pages) | Cited 1 time

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Investigation of the temporal integration of the acoustic reflex may be complicated by the operating characteristics of the instrumentation used to record the reflex. Several experiments were conducted to determine the operating characteristics of two impedance measuring systems (Madsen, model Z0−70 and Zwislocki Bridge (Grason Stadler, model 3), and to measure selected characteristics of the acoustic reflex, including (1) ’’threshold’’, (2) reflex intensity‐growth functions, and (3) temporal integration functions at ’’threshold’’ for several stimulus frequencies. Results indicate (1) a smaller impedance change may be identified with a Madsen Z0−70 due primarily to the higher S/N (signal‐to‐noise) ratio in that instrument; (2) differences in temporal integration functions obtained between the two instruments were partially accounted for by differences in the operating characteristics of the two measuring systems; (3) the slope of the growth‐intensity function decreases as signal duration decreases; and (4) the slope of the temporal integration function increases as the frequency of the eliciting stimulus increases.
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43.66.Yw Instruments and methods related to hearing and its measurement
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.64.Ha Acoustical properties of the outer ear; middle-ear mechanics and reflex

Properties of friction analyzers for [j]

Ronald A. Cole and William E. Cooper

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 177-182 (1977); (6 pages)

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See Also: Erratum

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Listeners were presented with stimuli from a nine syllable [?a]–[da] continuum (constructed using a natural speech [?a]) in which syllables differed in the duration of frication from 52 to 8 msec. In each experimental session, an initial identification test was conducted to determine the category boundary. This base‐line test was followed by one of three adaptation tests in which subjects were presented with repeated syllables. The adapting stimuli consisted of (a) a single [?a] adaptor with 52 msec of frication, (b) a single [?a] adaptor with 32 msec of frication, (c) a ’’variable’’ adapting sequence that included the first six members of the test series and had a mean frication duration of 37 msec. The variable adapting sequence produced an adaptation effect equal in magnitude to the effect produced by the single adaptor with 32 msec of frication. The adapting syllable containing 52 msec of frication produced a significantly larger effect. The results demonstrate that (a) selective adaptation of speech did not require presentation of a constant adapting syllable and (b) the amount of adaptation depends upon the mean duration of frication contained in the adapting material at least up to 52 msec. A second experiment was performed to determine whether adaptation along a [?a]–[da] continuum was linearly dependent upon friction duration at values beyond 52 msec by comparing adaption produced by [?i], [?i], and [di] adaptors, containing friction duration of 120, 60, and 12 msec, respectively. The results showed that [?i] and [?i] produced highly similar adaptation effects on a [?a]–[da] series. The results suggest that an analyzer underlying perception of [?] is neither linearly nor symmetrically tuned to a particular range of friction duration.
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43.70.Dn Disordered speech

Articulatory movements in VCV sequences

Thomas Gay

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 183-193 (1977); (11 pages) | Cited 4 times

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The purpose of this experiment was to study both the timing and positional properties of articulatory movements in VCV utterances. Conventional cinefluorographic techniques were used to track the movements of the upper lip, lower lip, jaw, tongue tip, and tongue body of two speakers who read randomized lists of VCV utterances containing the vowels /i,a,u/ and the consonants /p,t,k/, in all possible combinations. Results showed that the timing of articulatory movements in a VCV sequence are constrained by the intervocalic consonant, even if the gesture for the consonant is not a contradictory one. Anticipatory movements toward the second vowel always begin during the closure period of the intervocalic consonant. The appearance of carry over coarticulation effects depends on the phonetic identity of the particular segment or degree of involvement of the articulator. Carry over effects, like anticipatory effects, did not extend beyond an immediately adjacent segment. These findings suggest that the rules governing the segmental input to a speech string might be simpler than present models suggest.
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43.72.Ar Speech analysis and analysis techniques; parametric representation of speech
43.70.Fq Acoustical correlates of phonetic segments and suprasegmental properties: stress, timing, and intonation
43.70.Bk Models and theories of speech production

Identification of speech sounds displayed on a vibrotactile vocoder

Grace H. Yeni‐Komshian and Moise H. Goldstein, Jr.

J. Acoust. Soc. Am. Volume 62, Issue 1, pp. 194-198 (1977); (5 pages)

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A vocoder‐type speech analyzer interfaced to the tactile display of an Optacon was used to investigate how subjects learned, over a six‐week period, to identify the vibrotactile patterns of different speech signals. Closed sets of four vowel durations, three different vowels, and four spondee words constituted the test material. Learning to identify vibrotactile patterns required many hours of training. Subjects in this study showed significant improvement in the identification of all three types of speech signals, especially the vowel durations and spondee words. Tests for transfer at the end of training showed that shifting the locus of stimulation did not result in decrement in performance.
Show PACS
43.70.Dn Disordered speech
43.66.Wv Vibration and tactile senses
43.70.Jt Instrumentation and methodology for speech production research
43.72.Ar Speech analysis and analysis techniques; parametric representation of speech
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