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Journal of the Acoustical Society of America

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Feb 1978

Volume 63, Issue 2, pp. 313-634

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Sound radiation from an accelerated or decelerated sphere

A. Akay and T. H. Hodgson

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 313-318 (1978); (6 pages)

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A careful review of the current literature has led to a more complete theoretical analysis of the sound radiation from an accelerated or decelerated sphere. The acoustic field has been calculated for an accelerated sphere in an arbitrary fluid medium, which shows the effect of the fluid density on the radiated sound pressure. The radiated sound pressure from an impulsively accelerated sphere has been compared with a finite acceleration case in order to emphasize the effect of the rate of change of velocity on the pressure waveform. Energy calculations have been made in both the time and frequency domains in order to identify the sources of radiated acoustic energy and the stored nearfield energy and also to demonstrate conclusively that the energy lost in the acceleration or deceleration is dissipated as sound.
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43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.20.Tb Interaction of vibrating structures with surrounding medium
43.20.Bi Mathematical theory of wave propagation

Surface wave resonances in sound scattering from elastic cylinders

J. W. Dickey and H. Überall

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 319-320 (1978); (2 pages) | Cited 4 times

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It is shown that the elastic‐type surface waves (Rayleigh wave, etc.) which enter in a description of sound scattering from elastic objects, exhibit resonances at the eigenfrequencies of the elastic body. These resonances can be interpreted in terms of Regge poles.
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43.20.Fn Scattering of acoustic waves
43.35.Pt Surface waves in solids and liquids

Theory of scattering by rigid bodies with thin liquid coatings

Thomas J. Eisler

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 321-327 (1978); (7 pages)

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A plane wave is incident on a rigid body which is partially or totally surrounded by a thin liquid coating whose (possibly variable) density and sound velocity differ from those of the ambient medium. By assuming the incident wavelength to be large compared with coating thickness, approximate expressions for the scattered field are obtained in integral form. By further assuming incident wavelength to be small compared with typical dimensions of the rigid body, the integrals are evaluated asymptotically and the scattered field is expressed in terms of contributions from certain scattering centers of the coating, viz., the specular point and points at which incident rays are perpendicular to the edge of the coating. As an example the method is applied to the problem of a partially coated sphere.
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43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation

Radiated power and radiation loading of cylindrical surfaces with nonuniform velocity distributions

Peter R. Stepanishen

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 328-338 (1978); (11 pages) | Cited 2 times

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A general approach is presented to evaluate the radiation loading and radiated power from a nonuniform harmonically vibrating surface on an infinite cylinder. The approach utilizes a combined Green’s function and Fourier integral technique to develop integral expressions for the generalized radiation impedance and power radiated from the surface. The general expressions are shown to reduce to previously developed expressions for several problems of interest, i.e., a uniformly vibrating band on a cylinder, a vibrating piston on a cylinder, and various circumferentially varying velocity distributions on a cylinder with no axial variation. Simplified integral expressions are then presented for a particular velocity distribution of interest. Although the integrals can be evaluated asymptotically, in general the integrals must be numerically integrated. Extensive numerical results are presented and discussed in order to illustrate the characteristics of the radiation loading and radiated power.
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43.20.Tb Interaction of vibrating structures with surrounding medium
43.20.Hq Velocity and attenuation of acoustic waves
43.40.Ey Vibrations of shells

Design of a curved‐face parametric projector

Mary Beth Bennett and Charles M. Slack, III

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 339-345 (1978); (7 pages)

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A transducer capable of penetrating marine sediments with multiple, rectangular beams which are broad (20°–30°) in one plane and narrow (2°–3°) in the other plane at frequencies of 10–20 kHz was desired. Transducer size constraints prohibited attaining such a beam conventionally; thus, parametric operation of a rectangular transducer was examined. A relatively high parametric source level of 190 dB re 1 μPa at 1 m was also desired, and the resulting cavitation and acoustic intensity considerations dictated a curved‐face transducer design. Primary and parametric beam patterns and propagation data obtained for both a rectangular transducer and a curved‐face transducer confirmed the prediction techniques being employed. Parametric beam patterns in the broad plane exhibited minor lobes with the minor‐lobe structure of the curved‐face transducer beam less pronounced than that experienced with the rectangular transducer. Sound pressure levels and beam patterns measured for the curved‐face projector confirmed that a curved‐face transducer can be operated parametrically to produce high‐power, low‐frequency rectangular beams.
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43.25.Lj Parametric arrays, interaction of sound with sound, virtual sources
43.38.Ar Transducing principles, materials, and structures: general

Nonlinear attenuation of an N wave propagating in a tube, including dissipation due to wall effects

Akira Nakamura, Ryoichi Takeuchi, and Samon Oie

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 346-352 (1978); (7 pages)

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Theoretical computations are made for the variation of waveform of an N wave propagating in a circular tube. The change with distance of the slope of the straight‐line segment of the waveform at its axis crossing is calculated. Various assumptions are made in the calculation to isolate the separate contributions of weak‐shock theory and tube‐wall effects. The change in slope is as predicted by weak‐shock theory. The slope is affected by tube‐wall dissipation, but virtually unaffected by velocity dispersion. Measurements are reported pressure profiles of N waves at various distances in a tube. Experiments were done with several different gases. The agreement between theoretical and observed values is fairly good.
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43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.25.Ed Effect of nonlinearity on velocity and attenuation

Statistics of normal mode amplitudes in a random ocean. I. Theory

L. B. Dozier and F. D. Tappert

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 353-365 (1978); (13 pages) | Cited 34 times

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A statistical theory of acoustic propagation in a model random ocean, valid in the limit of low acoustic frequency, is presented. A random internal‐wave model gives sound‐speed fluctuations δc (r,z,t) about a deterministic profile ? (z). Using normal modes of ? (z) as a basis, the theory gives quantitative estimates of statistical moments of the mode amplitudes ψn(r,t), which are randomly coupled via δc. Invoking a quasistatic approximation, the theory treats time as a parameter. From any initial (r=0) distribution of modal powers ‖ψn‖2, the evolution of their averages to an equilibrium is predicted by ’’coupled power’’ equations. The theory makes similar predictions for average fluctuations of the modal powers about their means. In the equilibrium limit, the theory gives the full probability distribution of the ψn.
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43.30.Bp Normal mode propagation of sound in water
43.30.Jx Radiation from objects vibrating under water, acoustic and mechanical impedance
43.30.Cq Ray propagation of sound in water
43.20.Bi Mathematical theory of wave propagation

Sound velocity–density relations in sea‐floor sediments and rocks

Edwin L. Hamilton

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 366-377 (1978); (12 pages) | Cited 10 times

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In studies in underwater acoustics, geophysics, and geology, the relations between sound velocity and density allow assignment of approximate values of density to sediment and rock layers of the earth’s crust and mantle, given a seismic measurement of velocity. In the past, single curves of velocity versus density represented all sediment and rock types. A large amount of recent data from the Deep Sea Drilling Project (DSDP), and reflection and refraction measurements of sound velocity, allow construction of separate velocity–density curves for the principal marine sediment and rock types. The paper uses carefully selected data from laboratory and in situ measurements to present empirical sound velocity–density relations (in the form of regression curves and equations) in terrigenous silt clays, turbidites, and shale, in calcareous materials (sediments, chalk, and limestone), and in siliceous materials (sediments, porcelanite, and chert); a published curve for DSDP basalts is included. Speculative curves are presented for composite sections of basalt and sediments. These velocity–density relations, with seismic measurements of velocity, should be useful in assigning approximate densities to sea‐floor sediment and rock layers for studies in marine geophysics, and in forming geoacoustic models of the sea floor for underwater acoustic studies.
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43.30.Dr Hybrid and asymptotic propagation theories, related experiments
43.40.Ph Seismology and geophysical prospecting; seismographs
92.10.Vz Underwater sound
91.50.Ey Seafloor morphology, geology, and geophysics

Characterization and simulation of underwater acoustic signals reflected from the sea surface

G. E. Lord and T. D. Plemons

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 378-385 (1978); (8 pages)

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The properties of underwater acoustic signals scattered in the forward direction by the sea surface have been analyzed statistically. It is shown that the energy of the scattered signal is described adequately by a beta distribution. The beta parameters (α, β) can be estimated using ensemble estimates of the mean and variance of the normalized scattered energies. The mean scattered energy in turn can be related to the surface roughness parameter g=4πσsinϑ/λ, where σ is the rms surface wave height, ϑ is the grazing angle, and λ is the acoustic wavelength. For a wind driven, rough surface, the acoustic frequency and grazing angle were varied to obtain values of g from 0.5 to 1.4. The structural changes of pulses reflected by the surface are also treated statistically by means of a linear autoregressive model. It is shown that models of relatively low order (e.g., first or second, thus containing few parameters) provide a fairly complete description of forward‐scattered signals. The converse problem of using these models to simulate data having the appropriate statistical properties is also discussed and examples are given.
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43.30.Bp Normal mode propagation of sound in water
43.30.Dr Hybrid and asymptotic propagation theories, related experiments
43.30.Gv Backscattering, echoes, and reverberation in water due to combinations of boundaries

Signal speed in long‐range propagation

Stephen K. Mitchell and Loyd D. Hampton

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 386-390 (1978); (5 pages)

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The speed of acoustic signals traveling from a large number of explosive sources in the Northeast Pacific and North Atlantic oceans has been measured and compared with the predictions of ray theory. Signal speed is defined here as the horizontal source‐to‐receiver range divided by the time from source detonation to the earliest detection of the signal at the receiver. The ray‐tracing predictions show that signal speed may vary by as much as 1% or more; changes of 15 m/s may occur within a 1.8‐km range interval. The nature of the signal‐speed‐versus‐range curve depends on the sound‐velocity profile and the source and receiver depths. The measurements show that the predicted features, in particular the regular fluctuation of signal speed, are readily observed.
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43.30.Bp Normal mode propagation of sound in water
43.30.Cq Ray propagation of sound in water
92.10.Vz Underwater sound
43.20.Dk Ray acoustics

Acoustic sidebands from cw sources towed at long ranges in the deep ocean

Dan J. Ramsdale

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 391-395 (1978); (5 pages)

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Three cw sources (9.8, 110, and 262 Hz) were towed at approximately 7 knots along a great circle track from Antigua, W.I., to the Grand Banks of Newfoundland. Acoustic data from each were recorded on a bottom‐mounted hydrophone near Antigua, providing source‐to‐receiver distances of from 100 to 2800 km. High‐resolution spectral analysis centered at each frequency showed that while no acoustic sidebands were discernible at 9.8 Hz, they were observable over the entire track for both the higher frequencies. Except for expected statistical fluctuations, the upper and lower sidebands were of equal amplitude and symmetrically placed about the carrier frequency. In regions of strong convergence zone activity the sideband level displayed similar peak‐to‐null variation to those of the carrier, although the peak‐to‐null ratio was smaller than for the carrier. Detailed environmental data were available only near the sources. A high degree of correlation was observed between the sideband levels and the wave and swell heights when the sources were towed through a storm which occurred some 2000 km from the receiver. Sideband levels computed from the single bounce sinusoidal surface theory of Roderick and Cron [J. Acoust. Soc. Am. 48, 759–766 (1970)] using swell amplitude data at the sources agreed well with the measured levels for both frequencies during the stormy period. The separation of the sidebands in frequency from the carrier was the same for both source frequencies, was not affected by the convergence zone behavior of the sideband levels, and decreased as the sources approached and transited the stormy area.
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43.30.Gv Backscattering, echoes, and reverberation in water due to combinations of boundaries
43.30.Bp Normal mode propagation of sound in water
43.30.Jx Radiation from objects vibrating under water, acoustic and mechanical impedance
92.10.Vz Underwater sound

Observations of the propagation of very short ultrasonic pulses and their reflection by small targets

J. P. Weight and A. J. Hayman

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 396-404 (1978); (9 pages) | Cited 6 times

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The field of a circular ultrasonic transducer emitting a single‐cycle pulse into water has been observed using a specially constructed small (150 μm) wide‐band receiving probe and a compact stroboscopic schlieren system. The theoretically predicted plane‐wave and diffracted edge‐wave components of the field have been resolved. Good agreement with the theory for a pistonlike source is obtained, except in a region less than 1.5 transducer radii from the transducer. The output of the transducer used in the transmit–receive mode to detect small targets has been measured and the results are in accord with a time‐domain principle of reciprocity between transmission and reception. Implications of the results for field plotting and for the location and characterization of small targets are considered.
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43.30.Dr Hybrid and asymptotic propagation theories, related experiments
43.20.Fn Scattering of acoustic waves
43.20.Px Transient radiation and scattering

Ray theory for wide classes of sound‐speed profiles with two‐dimensional variation

DeWayne White

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 405-419 (1978); (15 pages)

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This paper presents closed‐form ray‐path and travel‐time equations using solutions of the eikonal equation for wide classes of sound‐speed profiles which vary with range as well as depth. The geometric intensity equation is also given. In the past, ray theory for two‐dimensional sound‐speed variation has been treated mainly by numerical methods. Closed‐form solutions have been available for only a few profiles of a simple form. In this paper the sound‐speed profile is expressed in terms of x and y of a transformed coordinate system in which x and y are functions of depth and range. This transformation and sound‐speed function are such that the transformed eikonal equation reduces to a partial differential equation separable in x and y. The closed‐form ray equations are calculated in terms of x and y, then the results are converted to and presented in depth and range coordinates. The general characteristics of large classes of allowable transformations are presented. Five specific examples of allowable transformation are presented. Three different profile forms are treated in detail for the polar coordinate transformation. Numerical results, including ray diagrams, are presented for these three forms. These three numerical examples provide controls suitable for test cases testing approximate numerical ray‐trace methods.
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43.30.Bp Normal mode propagation of sound in water
43.30.Cq Ray propagation of sound in water
43.20.Dk Ray acoustics

High‐resolution cross‐sensor beamforming for a uniform line array

Homer P. Bucker

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 420-424 (1978); (5 pages)

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The methods of high‐resolution spectral analysis can be used for high‐resolution cross‐sensor beamforming for a uniform line array. In this paper two high‐resolution techniques (maximum entropy and discrete decomposition) are applied to the cross‐sensor field. Sample calculations illustrate the effectiveness of these methods in the case of a realistic multiwave acoustic field plus narrowband Gaussian noise.
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43.60.Cg Statistical properties of signals and noise
43.30.Vh Active sonar systems

A novel approach to digital beamforming

Roger G. Pridham and Ronald A. Mucci

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 425-434 (1978); (10 pages) | Cited 3 times

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For many sonar applications, the sensor outputs of a hydrophone array are sampled at a rate significantly higher than that required for waveform reconstruction when digital beamforming is used. The reason for this is that the number of synchronous, or ’’natural,’’ beampointing directions is proportional to the beamformer input rate. This paper presents an implementation of a digital beamformer that achieves the desired synchronous beams while minimizing the sensor channel sampling rate requirement. The technique employs zero padding of sensor data followed by digital interpolation filters to achieve vernier beamformer delays. Interpolation filtering can be done either at the beamformer input or output to minimize processing requirements. The resulting structure realizes a hardware savings since both A/D converter and cable bandwith requirements can be traded off against digital processing complexity to achieve an optimal partitioning.
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43.60.Gk Space-time signal processing, other than matched field processing
43.30.Vh Active sonar systems

Alternate derivation of the generalized beam pattern

David P. Vasholz

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 435-435 (1978); (1 page)

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A derivation of the generalized beam pattern associated with approximate solutions to the source extraction integral equation is presented which has a number of advantages over the author’s original treatment. Specifically it is more direct, makes fewer assumptions regarding the algorithm employed, and makes explicit some interesting relationships with the local nature of the basic field equation.
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43.60.Cg Statistical properties of signals and noise

Tympanic membrane perforations in cats: Configurations of losses with and without ear canal extensions

Barbara Kruger and Juergen Tonndorf

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 436-441 (1978); (6 pages) | Cited 2 times

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In cat, a small tympanic membrane (TM) perforation produces a low‐frequency loss—in terms of sound pressure changes (ΔSP) in front of the TM re a 10‐μV round window cochlear microphonic (RW CM) —that varies inversely with frequency at a rate of 12 dB/octave with a surgically shortened external auditory meatus (EAM). Losses were determined at the outer opening (ΔSP00) and at the TM (ΔSPTM) of four artificial EAM’s of various lengths, volumes, and leakiness. In the low‐frequency region, a leaky EAM produced a flat loss. In the midfrequency region, the flatness of losses was attributable to (1) the length of the EAM and (2) the location at which the loss was determined. EAM volume was not related to the configuration of the loss. Losses, under all conditions, were always identical in shape and magnitude for the open and closed systems. Clinically, hearing losses due to TM perforations are essentially frequency independent, especially in the low frequencies. The relation between voltage changes (ΔV) across the transducer and losses with different EAM’s suggests that the discrepency between audiometric results and CM losses—at least in the high and midfrequencies—may be due to the use of precalibrated SPL’s in clinical audiometry.
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43.64.Ha Acoustical properties of the outer ear; middle-ear mechanics and reflex

Auditory‐nerve response from cats raised in a low‐noise chamber

M. Charles Liberman

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 442-455 (1978); (14 pages) | Cited 61 times

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A litter of four cats, born and raised in a soundproofed chamber, was studied in an attempt to determine which, if any, features of the auditory‐nerve response from routinely available cats might be due to the chronic effects of noise exposure. Two features of routine‐normal response were especially suspect in this regard: (1) a ’’notch’’ in the distribution of single‐unit thresholds centered at characteristic frequencies (CF’s) near 3 kHz and (2) a compression of the distribution of rates of spontaneous discharge for units with CF above 10 kHz. A third feature of response in routine animals was the presence of a small number (roughly 10%) of units with virtually no spontaneous discharge and very high thresholds, sometimes 80 dB less sensitive than high‐spontaneous units of similar CF. In the data from chamber‐raised animals, the high‐spontaneous units showed exceptionally low thresholds at all CF regions, however, there were signs of the midfrequency notch in the threshold distribution of at least two of these animals. The compression of the spontaneous rate distribution was not seen in any of the three most sensitive animals. The data suggest that there is a significant amount of ’’normal pathology’’ in the high‐CF units from routine animals. Low‐spontaneous, high‐threshold units were present in all four chamber‐raised ears with the same characteristics as in routine animals (exceptionally narrow tuning curves and exceptionally low maximum discharge rates) and at roughly the same percentage of the unit sample. A class of units with medium spontaneous rates and intermediate thresholds could also be identified. The possible significance of a classification of auditory‐nerve units according to spontaneous rate is discussed.
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43.64.Pg Electrophysiology of the auditory nerve
43.64.Ri Evoked responses to sounds
43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.66.Gf Detection and discrimination of sound by animals

Categorical perception—phenomenon or epiphenomenon: Evidence from experiments in the perception of melodic musical intervals

Edward M. Burns and W. Dixon Ward

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 456-468 (1978); (13 pages) | Cited 7 times

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Categorical perception was investigated in a series of experiments on the perception of melodic musical intervals (sequential frequency ratios). When procedures equivalent to those typically used in speech‐perception experiments were employed, (i.e., determination of identification and discrimination functions for stimuli separated by equal physical increments), musical intervals were perceived categorically by trained musicians. When a variable‐step‐size (adaptive) discrimination procedure was used, evidence of categorical perception (in the form of smaller interval‐width DL’s for ratios at identification category boundaries than for ratios within categories), although present initially, largely disappeared after subjects had reached asymptotic performance. However, equal‐step‐size discrimination functions obtained after observers had reached asymptotic performance in the adaptive paradigm were not substantially different from those initially obtained. The results of other experiments imply that this dependence of categorical perception on procedure may be related to differences in stimulus uncertainty between the procedures. An experiment on the perception of melodic intervals by musically untrained observers showed no evidence for the existence of ’’natural’’ categories for musical intervals.
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43.66.Lj Perceptual effects of sound
43.66.Hg Pitch
43.66.Fe Discrimination: intensity and frequency

Temporal integration of tone glides

M. Jane Collins and John K. Cullen, Jr.

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 469-473 (1978); (5 pages) | Cited 2 times

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Temporal integration of rising and falling tone glides against a 50–2800‐Hz background of noise at a sound pressure level of 60 dB re 20 μPa was studied in two experiments. Glides were in the frequency ranges 200–700 Hz and 1200–1700 Hz for durations of 5–120 ms. Results indicate an asymmetry in the detectability of rising and falling glides of short duration, with rising glides detected at lower signal intensities in both frequency ranges. These effects are discussed in terms of differences in pattern of frequency analysis of identical, but temporally reversed, waveforms.
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43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Fe Discrimination: intensity and frequency
43.66.Lj Perceptual effects of sound

Compatibility between psychophysical and physiological measurements of aural combination tones

Julius L. Goldstein, Gershon Buchsbaum, and Miriam Furst

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 474-485 (1978); (12 pages) | Cited 3 times

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Neural studies of combination‐tone (CT) responses in the eighth nerve and antroventral cochlear nucleus of anesthetized cats give evidence of stimuluslike intracochlear CT’s with a similar amplitude spectrum as inferred from human psychophysics. An unsolved problem raised in these studies is the gross discrepency between the phase of CT’s measured psychophysically and neurally. It is unknown whether incompatibility lies in the cochleae or the criteria for measuring CT’s in the different experiments. New psychophysical experiments were developed to clarify this issue. Secondary CT’s (SCT) were generated by the interaction between a primary cubic CT (CTT) and a third tone in the stimulus. The SCT measured by cancellation exhibits similar properties to those of a CT generated by the comparable two‐tone stimulus. The SCT is eliminated when the CCT is cancelled. These findings support the view that CT’S exist in the cochlea as spatially distinct, stimuluslike excitations, and that CT excitations are eliminated by psychophysical cancellation. The SCT phase provides a measure of the CCT phase without requiring direct cancellation of the CCT. Phase measurements by the new indirect and older direct methods imply that the CT phase may be constant with changing sound level of the primary stimulus as found in the neural studies; these measurements also reveal nonlinear phase effects not found in neural studies. The new data suggest that the CT phase discrepancy may be caused by a real difference between the nonlinear mechanisms in the alert humans and anesthetized cats, and provide new constraints for clarifying this issue through further study.
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43.66.Ki Subjective tones
43.66.Nm Phase effects
43.66.Ba Models and theories of auditory processes
43.64.Pg Electrophysiology of the auditory nerve

Verification of the optimal probabilistic basis of aural processing in pitch of complex tones

J. L. Goldstein, A. Gerson, P. Srulovicz, and M. Furst

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 486-497 (1978); (12 pages) | Cited 5 times

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Periodicity pitch for complex tones has been quantitatively accounted for by a two‐stage process of Fourier‐frequency analysis subject to random errors and significant nonlinearities, followed by an harmonic pattern recognizer that makes an optimum probabilistic estimate of the fundamental period of musical and speech sounds. The theory predicts that periodicity pitch is a multimodal probabilistic function of a given stimulus. A clear and empirically supported distinction is made between limitations on the pitch mechanism caused by the stochastic nature of aural frequency representation and by the deterministic resolution bandwidths of aural frequency analysis. This model was developed earlier [J. L. Goldstein, J. Acoust. Soc. Am. 54, 1496–1516 (1973)] to account for probabilistic data on pitch errors [A. J. M. Houtsma and J. L. Goldstein, J. Acoust. Soc. Am. 51, 520 (1972)] measured with periodic stimuli comprising two successive harmonics. This paper presents new predictions by the theory that were calculated, with computer simulation where needed, for known probabilistic pitch data from stimuli comprising three to six successive harmonics. Predicted pitch errors increase with increasing errors in estimating the frequencies of stimulus harmonics and decrease as more harmonics are added to the stimulus. Optimum processor theory fully accounts for the multicomponent pitch data on the basis of similar errors in estimating component stimulus frequencies as reported earlier, thus providing further evidence for the optimum probabilistic basis of aural signal processing in pitch of complex tones.
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43.66.Ba Models and theories of auditory processes
43.66.Hg Pitch
43.66.Lj Perceptual effects of sound
43.64.Pg Electrophysiology of the auditory nerve

Evidence for a general template in central optimal processing for pitch of complex tones

A. Gerson and J. L. Goldstein

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 498-510 (1978); (13 pages) | Cited 6 times

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Optimum prcessor theory sucessfully accounts for earlier pitch data by including the constraint that component tones in a complex stimulus are estimated as successive harmonics. This constraint gives the paradoxical prediction that a periodic complex tone comprising nonsuccessive harmonics cannot evoke periodicity pitch corresponding to its period. Most published data from pitch‐shift experiments imply the necessity for this constraint. New periodicity pitch experiments on pitch shift and musical interval recognition were performed which prove that the theoretical constraint is not generally true. New and old data are reconciled by replacing the maximum likelihood estimation of the theory with maximum posterior probability estimation and removing the successive harmonic constraint. Periodicity pitch is estimated by optimizing the match between the aurally measured frequencies of stimulus components and a general harmonic template over some a priori expected pitch range. The new, more general, formulation reduces in many experimental situations to the successive harmonic constraint as a special case.
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43.66.Hg Pitch
43.66.Ba Models and theories of auditory processes
43.66.Fe Discrimination: intensity and frequency

Detectability of varying interaural temporal differencesa)

D. Wesley Grantham and Frederic L. Wightman

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 511-523 (1978); (13 pages) | Cited 50 times

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Dectectability and salience of time‐varying interaural temporal differences (IATD’s) were measured in three experiments by determining observers’ ability to follow the temporal fluctuations of a ’’moving stimulus’’—a 3000‐Hz low‐pass computer‐generated noise presented binaurally with a sinusoidally varying IATD. In the first two experiments the peak IATD (Δt the ’’extent of movement’’) was manipulated to determine, for different rates of interaural variation (fm), threshold discriminability of the ’’moving’’ stimulus from a reference (two‐interval forced‐choice paradigm). The nonmoving reference was either a dichotic noise stimulus (experiment 1) or a diotic noise stimulus whose ’’image width’’ matched that of the excursions traced by the ’’moving stimulus’’ (experiment 2). Threshold Δt’s in the two experiments were similar, increasing from 30 μs at fm=0 Hz to 90 μs at fm=20 Hz, indicating a ’’low‐pass characteristic’’ for the binaural system. Thresholds decreased again for fm≳50 Hz, apparently because at these high rates of ’’movement’’ observers used other cues than the varying IATD’s to perform the task. The third experiment measured the threshold of a binaural click in the presence of a ’’moving noise’’ masker as a function of ’ifm and of the instantaneous IATD of the masker when the click was presented. As fm increased, click threshold gradually became independent of the masker’s instantaneous IATD, again suggesting a ’’low‐pass’’ characteristic for the binaural system; additionally, there was some evidence for a lag in the system’s response for fm≳5 Hz. The data from the three experiments are discussed in terms of results from other studies which have investigated temporal aspects of the binaural system. The possible existence of movement detectors in the auditory system is discussed.
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43.66.Pn Binaural hearing
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music

Psychophysical tuning curves measured in simultaneous and forward masking

Brian C. J. Moore

J. Acoust. Soc. Am. Volume 63, Issue 2, pp. 524-532 (1978); (9 pages) | Cited 17 times

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The level of a masker necessary to mask a probe fixed in frequency and level was determined as a function of masker frequency using a two‐interval forced‐choice technique. Both simultaneous‐ and forward‐ masking techniques were used. Parameters investigated include the level of the probe tone and the frequency of the probe tone. The general form of the psychophysical tuning curves obtained in this way is quite similar to that of single‐neurone tuning curves, when low‐level probe tones are used. However, the curves obtained in forward masking generally show sharper tips and steeper slopes than those found in simultaneous masking, and they are also generally sharper than neurophysiological tuning curves. For frequencies of the masker close to that of the probe a simultaneous masker was sometimes less effective than a forward masker. The results are discussed in relation to possible lateral suppression effects in simultaneous masking, and in relation to the observer’s use of pitch cues in forward masking. It is concluded that neither the simultaneous‐masking curves nor the forward‐ masking curves are likely to give an accurate representation of human neural tuning curves.
Show PACS
43.66.Dc Masking
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
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