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

Journal of the Acoustical Society of America

BROWSE VOLUMES

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

Mar 1979

Volume 65, Issue 3, pp. 565-877

Page 1 of 5 Pages Next Page | Jump to Page

Near and farfield of strip‐shaped acoustic radiators

C. J. Drost

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 565-572 (1979); (8 pages)

Full Text: | Download PDF

Show Abstract
The acoustic radiation produced by baffled flat strip‐shaped sources of infinite length is treated in detail. The nearfield intensity distribution, nearfield to farfield transition, and cylindrical farfield radiation is calculated for homogeneous radiator surface excitation; such beams are shown to partially focus at their last maximum of intensity. Farfield radiation is calculated for radiators with a Gaussian surface velocity distribution, for shaded transducers, and for arrays of strip‐shaped sources. The use of such radiators in Doppler flow measuring systems is discussed.
Show PACS
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.20.Bi Mathematical theory of wave propagation

Giant monopole resonances in the scattering of waves from gas‐filled spherical cavities and bubbles

G. Gaunaurd, K. P. Scharnhorst, and H. Überall

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 573-594 (1979); (22 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
Continuing our previous work on viscoelastic scattering of p waves from fluid‐filled spherical cavities in sound‐absorbing materials, we now perform the theoretical analysis needed for the complete study of the monopole mode of vibration. Our approach is based on the Breit–Wigner formulation of nuclear scattering theory, and from it we show how the scattering amplitudes consist of two parts, the smooth background of the evacuated cavity and the resonance contribution of the filler fluid. We present a complete analytical study of the giant fundamental resonance and its overtones in the monopole case. The results are then particularized to the Rayleigh region and also to the case of evacuated cavities in lossless rubber and to gas bubbles in water, recovering and extending previous results available in the literature. Studying the sound pressure level at the center of air‐filled cavities in lossy materials, we quantitatively determine how absorption shifts the resonance peaks and broadens their width. Using our theory we find that the width of the resonance peaks depends linearly on the resonance frequencies, and we show how this important result can be used to determine the shear absorption parameter of viscoelastic materials. We also find that the giant monopole resonance for air‐filled cavities in rubber contains a contribution from the shear waves in the cavity wall and another from the resonance oscillations of the air‐filling in a 15:1 ratio, for this particular material combination. We display numerous plots, some obtained from the analytic monopole formulas developed here, and some numerically obtained by computer for dipoles and quadrupoles. Finally, we show graphs of the summed scattering amplitudes fpp and fps accounting for the first twenty multipole contributions, and the dominance of the monopole term emerges again from this result. We have assumed ’’weak’’ absorption to simplify the analytical treatment, but any viscosity level can be handled by computer using this method.
Show PACS
43.20.Fn Scattering of acoustic waves
43.20.Ks Standing waves, resonance, normal modes
43.35.Mr Acoustics of viscoelastic materials
43.20.Bi Mathematical theory of wave propagation

Hybrid ray‐mode formulation of ducted propagation

L. B. Felsen and T. Ishihara

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 595-607 (1979); (13 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
High‐frequency propagation in waveguides or ducts can be formulated in terms of a guided mode or a ray expansion. When the duct is very wide, the excessively large number of modes or rays often necessitates the truncation of the resulting mode or ray series. This paper examines the truncation problem and shows that a hybrid formulation, in terms of a properly chosen number of rays and guided modes, can account for the remainder field in either case. The hybrid field representation has appealing physical content in that a few of the lowest modes account for the collective behavior of rays with many reflections, while a few of the lower‐order rays account for the collective behavior of the higher‐order guided modes. Other field representations involving rays, modes, a canonical integral, a continuous spectrum, and nearfield perturbation are also examined. Numerical comparisons for a specific example show the utility and range of validity of these alternative representations.
Show PACS
43.20.Fn Scattering of acoustic waves
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Dk Ray acoustics

Piston radiator: Some extensions of the theory

Martin Greenspan

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 608-621 (1979); (14 pages) | Cited 16 times

Full Text: | Download PDF

Show Abstract
Those results of the theory of the baffled, uniform‐piston radiator that can be calculated exactly are extended to some other cases, especially the simplest case of a simply supported radiator, the simplest case of a clamped‐edge radiator and a Gaussian radiator. It is also shown that from the solution to a problem with boundary conditions framed in terms of velocity, the solution to a corresponding problem, having boundary conditons framed in terms of pressure, can be obtained very easily.
Show PACS
43.20.Px Transient radiation and scattering
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.20.Bi Mathematical theory of wave propagation

Coherence estimates for signals propagated through acoustic channels with multiple paths

W. Jobst and X. Zabalgogeazcoa

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 622-630 (1979); (9 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Theoretical estimates of space, time, and frequency coherence are obtained for a sound field generated by a moving source and observed at a stationary array of sensors. It is shown that spatial coherence depends principally upon the spread of ray‐path‐arrival angles at the receiving sensors and on the orientation of the receiving array to the sound field. Temporal coherence depends upon the ray‐path angle spread at the source and on source motion. Oscillatory source motion introduces frequency modulation of the transmitted signal with sideband levels related to projector displacement amplitude. Frequency coherence depends upon the time spread between arrivals which propagate over different acoustic paths. Examples of theoretical coherence functions are presented for multipath channels of interest in underwater acoustics.
Show PACS
43.20.Dk Ray acoustics
43.30.Bp Normal mode propagation of sound in water
43.60.Cg Statistical properties of signals and noise
43.20.Bi Mathematical theory of wave propagation

Prediction of the sound field radiated from axisymmetric surfaces

W. L. Meyer, W. A. Bell, M. P. Stallybrass, and B. T. Zinn

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 631-638 (1979); (8 pages) | Cited 4 times

Full Text: | Download PDF


See Also: Erratum

Show Abstract
A general analytical method for determining the radiated sound fields from axisymmetric surfaces of arbitrary cross section with general boundary conditions is developed. The method is based on an integral representation for the external solutions of the Helmholtz equation. An integral equation is developed governing the surface potential distribution which gives unique solutions at all wavenumbers. The axisymmetric formulation of the problem reduces its solution to the numerical evaluation of line integrals by Gaussian quadrature. The applicability of the solution approach for both a sphere and finite cylinder is demontrated by comparing the numerical results with exact analytical solutions for both discontinuous and continuous boundary conditions. The method is then applied to a jet‐engine‐inlet configuration and the computed results are in good agreement with exact values.
Show PACS
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.20.Tb Interaction of vibrating structures with surrounding medium

Impulse response function for a scalar wave source in a compliant baffle

M. W. P. Strandberg

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 639-646 (1979); (8 pages)

Full Text: | Download PDF

Show Abstract
The velocity potential impulse response function is computed for a cylindrical piston in a compliant baffle. It is shown that, in general, the impulse response is that of a piston in a noncompliant baffle, plus a small wake, or reverberation, which dies out in a time the order of the transit time of the wave to the point in space. The slow decay of the wake means that the energy in the wake from a short pulse will be considerable fraction of the total energy. The solution is obtained in closed from from a baffle which matches the fluid impedance. Second sound heat pulse propagation in helium II obeys the scalar wave equation and it will have a second sound heat pulse impulse response which is isomorphous with that of the pressure wave in a fluid. It is pointed out that the analyses of the transient electromagnetic field of a vertical dipole antenna above a conducting earth, and the seismic transients in a layered earth can be of use in discussing the acoustic problem explored here.
Show PACS
43.20.Px Transient radiation and scattering
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.20.Bi Mathematical theory of wave propagation

Asymptotic methods for the first compressional head wave arrival in a fluid‐filled borehole

L. Tsang and J. A. Kong

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 647-654 (1979); (8 pages)

Full Text: | Download PDF

Show Abstract
Asymptotic results are obtained for the first compressional head wave arrival in a fluid‐filled borehole with a modified asymptotic technique. The results are verified with direct numerical integrations and shown to be quite different from those obtained with the ordinary asymptotic techniques. The modified asymptotic technique accounts for the effect of an extraneous pole, which is neglected in the ordinary asymptotic method. The basic assumption in the modified asymptotic method is that the observation point must be far away from the source point, whereas in the ordinary asymptotic technique, the frequency is assumed to be large. The pressure responses of the first compressional arrival are illustrated and compared. It is found that the amplitudes of the compressional arrivals are strongly dependent on the Poisson’s ratio and the compressional velocity of the formation.
Show PACS
43.20.Bi Mathematical theory of wave propagation
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods

Scattering of elastic waves by randomly distributed and oriented scatterers

Vijay K. Varadan

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 655-657 (1979); (3 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
We analyze the two‐dimensional problem of multiple scattering by randomly distributed and oriented scatterers, and compare the results with those for the aligned scatterers. Waterman’s T‐matrix approach in conjunction with the statistical averaging for both position and orientation are employed to obtain the phase velocity and attenuation due to geometric dispersion for a wide range of frequencies. Analytical expressions for the dispersion relation are also derived at low frequencies for both randomly distributed and oriented inclusions and cracks.
Show PACS
43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation

The absorption of sound by pine trees

Stephen H. Burns

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 658-661 (1979); (4 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
This paper describes a study of the absorption of sound by pine trees. Swept frequency measurements were made with small boughs in a reverberant box. Tests for branch and needle resonances were also made. The observed absorption is comparable to the expected thermoviscous absorption in the boundary layer of air that surrounds the individual needles.
Show PACS
43.28.Fp Outdoor sound propagation through a stationary atmosphere, meteorological factors
43.20.Fn Scattering of acoustic waves
43.20.Hq Velocity and attenuation of acoustic waves

On the aerodynamic noise source in circular saws

H. S. Cho and C. D. Mote, Jr.

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 662-671 (1979); (10 pages)

Full Text: | Download PDF

Show Abstract
The character of the dominant aerodynamic noise source for rotating rigid circular saws is concluded to be represented by a point dipole model. The source strength is directly dependent upon Reynold’s number and saw design. A theoretical model is presented for prediction of the farfield noise. Experimental measurement of the fluctuating lift force on particular tooth models was used to identify the dipole source and a hot wire anemometer, rotating with the saw, measured the tooth wake. The theoretical predictions of dipole noise dependence upon parameter variation are generally consistent with literature noise data.
Show PACS
43.28.Ra Generation of sound by fluid flow, aerodynamic sound and turbulence
43.50.Nm Aerodynamic and jet noise
43.50.Jh Noise in buildings and general machinery noise

Forward scattering of underwater sound and its frequency dependence on the medium

R. S. Andrews

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 672-674 (1979); (3 pages)

Full Text: | Download PDF

Show Abstract
In the interference region of forward scattered sound by thermal inhomogeneities, there appears to exist a dominant thermal patch size for scattering at a given frequency. Several published results are examined and it is shown that over a decade of frequencies, the dominant (or effective) scattering patch size shows an f−5/2 frequency dependence. It also appears that a minimum patch size of approximately 1 cm is reached and that the frequency selectivity disappears after this value has been reached.
Show PACS
43.30.Bp Normal mode propagation of sound in water
43.30.Gv Backscattering, echoes, and reverberation in water due to combinations of boundaries

A normal mode theory of acoustic Doppler effects in the oceanic waveguide

Kenneth E. Hawker

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 675-681 (1979); (7 pages) | Cited 9 times

Full Text: | Download PDF

Show Abstract
This paper considers the problem of computing the acoustic field generated by a moving point source. In particular, the acoustic field is obtained in terms of the normal modes of a horizontally stratified ocean. The source motion is assumed to be uniform (unaccelerated), but is not restricted to a path radial to the receiver. The structure of the Fourier inversion integral is carefully analyzed and an evaluation is carried out by the method of stationary phase. The stationary phase point is explicitly computed as an expansion in powers of the ratio of the source speed to the mode group velocity. The resulting expression for the velocity potential is examined for Doppler effects for both instantaneous (modal) Doppler as well as Doppler determined by a finite bandwidth Fourier transform.
Show PACS
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

The existence of Stoneley waves as a loss mechanism in plane wave reflection problems

Kenneth E. Hawker

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 682-686 (1979); (5 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
In a previous paper [’’Influence of Stoneley waves on plane‐wave reflection coefficients: Characteristics of bottom reflection loss,’’ K. E. Hawker, J. Acoust. Soc. Am. 64, 548 (1978)] it was shown that for certain configurations of layered fluids overlying a rigid (solid) substrate, the reflection loss would display narrow peaks of significant amplitude. It was suggested in that paper that these peaks were due to excitation of Stoneley waves at the fluid–solid interface. In the present paper this association is made more precise and definite. Through an extension of the classical theory of Stoneley waves to the case of inhomogeneous media, it is shown that the angles at which the reflection‐loss peaks occur are precisely those angles for which the horizontal component of phase velocity in the fluid equals the Stoneley wave phase velocity. In addition, the near independence of the reflection loss peaks on frequency is explained quantitatively.
Show PACS
43.30.Bp Normal mode propagation of sound in water
43.30.Dr Hybrid and asymptotic propagation theories, related experiments
43.20.Bi Mathematical theory of wave propagation

Effect of periodic surface corrugation on the propagation of Rayleigh waves

S. R. Seshadri

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 687-694 (1979); (8 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
The Rayleigh wave interaction in an elastically isotropic half space having a free surface with weak sinusoidal corrugations in one direction is investigated for the case of propagation normal to the length of the corrugations. Simple and asymptotically exact analytical expressions are deduced with the help of a singular perturbation procedure for the characteristics of the wave interaction. The theory is applied to obtain the characteristics of the selective reflection of a Rayleigh wave incident on a moderately long periodic array of shallow grooves etched on the free surface. The results obtained from the present asymptotic theory are compared with those previously deduced from an empirical equivalent network approach and a phenomenological coupled mode theory.
Show PACS
43.35.Pt Surface waves in solids and liquids

Statistical models of coupled dynamical systems and the transition from weak to strong coupling

P. W. Smith, Jr.

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 695-698 (1979); (4 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
The statistical model for steady‐state response of a coupled dynamical system that is used in both room acoustics and statistical energy analysis is taken as the hypothesis. The model is defined by the fundamental equations of linear relation between the response energies of the subsystems and the input powers. Additional restrictions arise from the principle of reciprocity. The model is used to examine the effect of variable strength of coupling between the subsystems and the transition from weak to strong coupling. Results familiar from modal analysis [J. Acoust. Soc. Am. 63, 1081–1083 (1978)] are derived without introducing modal concepts.
Show PACS
43.55.Ka Computer simulation of acoustics in enclosures, modeling
43.40.At Experimental and theoretical studies of vibrating systems
43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response

Freeway noise and high‐rise balconies

Daryl N. May

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 699-704 (1979); (6 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
The sound levels on balconies above the 8th floor of high‐rise buildings situated 200 ft or so from freeway edge‐of‐pavements were found to be about 10 dB higher than those occurring on the ground floor. Equivalent sound levels on these balconies during the day were in the range 70–80 dBA depending on the size of the freeway; these sound levels are as high as those at ground level 50 ft from the edge‐of‐pavements of the freeways concerned. However, the use of sound absorptive material on a normal front‐walled balcony was shown to produce substantial noise reductions: treatment of the ceiling alone resulted in a 4–5 dB reduction, while a 7–8 dB reduction occurred with the addition of absorption equal, in Sabins, to a little over one‐third the area of the balcony surfaces.
Show PACS
43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles
43.55.Ti Sound-isolating structures, values of transmission coefficients
43.50.Jh Noise in buildings and general machinery noise

Subjective loudness and annoyance of filtered N‐wave sonic booms

A. Niedzwiecki and H. S. Ribner

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 705-707 (1979); (3 pages)

Full Text: | Download PDF

Show Abstract
The contribution of the ’’infrasonic’’ low‐frequency content of sonic boom N waves to subjective loudness and annoyance has been investigated. An extended low‐frequency response loudspeaker‐driven simulation booth was employed, with computer‐generated input test signals. For test N waves of 1 ms rise time and 150 ms duration, frequencies below 25 and 50 Hz, respectively, were cut off by digital filters simulating simple RC circuits. The filtered signal amplitude was adjusted versus the amplitude (48 Pa) of a reference unfiltered N wave (effective low‐frequency cutoff ∠0.1 Hz) until the two sounded equally loud (first experiment) or equally annoying (second experiment). The amplitude differences for equality were very slight: less than 0.6 dB at most. Surprisingly, while loss of the low frequencies slightly decreased the loudness, it slightly increased the annoyance.
Show PACS
43.50.Ba Noisiness: rating methods and criteria
43.66.Cb Loudness, absolute threshold
43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles
43.28.Mw Shock and blast waves, sonic boom

Measurements of the radiation impedance presented to a source in a reverberant room containing a rotating diffuser

David Alan Bies and Colin H. Hansen

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 708-718 (1979); (11 pages)

Full Text: | Download PDF

Show Abstract
The radiation impedance of a stationary sound source mounted in the side wall of a reverberant chamber has been investigated using three separate sources over the frequency range from 100 to 2000 Hz. The effect of a rotating diffuser on the measured radiation impedance has been investigated over a range of diffuser rotational speeds up to 50 rpm. The measurements show that a rotating diffuser is necessary to achieve an average radiation impedance equal to or approaching free field, and a rotational speed of between 20 and 30 rpm is sufficient for this purpose. The measurements suggest that the average radiation impedance may in part be dependent upon the source size and that the rotating diffuser has more effect on the radiation impedance for large sources.
Show PACS
43.55.Nd Reverberation room design: theory, applications to measurements of sound absorption, transmission loss, sound power
43.50.Cb Noise spectra, determination of sound power
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response

The response of a cavity backed panel to external airborne excitation: A general analysis

R. W. Guy

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 719-731 (1979); (13 pages) | Cited 7 times

Full Text: | Download PDF

Show Abstract
A multimodal analysis is made of the response of a cavity‐backed panel to an arbitrarily defined external forcing function. A general solution is developed which details the systems ’’characteristic functions.’’ These functions are examined and their properties detailed, in particular, the evaluation of poles and their representation in partial fraction form is achieved. Any external forcing function, provided that it is susceptible to finite Fourier cosine transformation with respect to spatial dependence and Laplace transformation with respect to temporal history, may be applied to the ’’characteristic functions’’ to determine the panel response. The general analysis is applied to the specific case of constant external pressure loading and the derived expressions are favorably compared with, and represent a further development of an accepted contemporary work.
Show PACS
43.55.Rg Sound transmission through walls and through ducts: theory and measurement

A bispectral synthesizer

Kimio Sasaki and Takuso Sato

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 732-739 (1979); (8 pages)

Full Text: | Download PDF

Show Abstract
Methods for synthesizing a random signal with a preassigned power spectrum and the amplitude characteristics of a bispectrum are discussed from the standpoint of phase relationship with the bispectrum. A new approach is proposed, which uses a bandpass filter array, a multiplicatory array, and Gaussian white noise. Further, a random signal corresponding to the Japanese vowel [a] is synthesized by using the constructed device, according to the analyzed data of a voiced vowel [a]. The results of the experiments show the usefulness of the synthesizer.
Show PACS
43.60.Cg Statistical properties of signals and noise

Source extraction in a random medium

David P. Vasholz

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 740-746 (1979); (7 pages)

Full Text: | Download PDF

Show Abstract
A general formulation of the problem of extracting information about nontransient sources immersed in a randomly fluctuating medium is presented. The formulation is based upon a Green’s function approach in which the medium is treated as a random linear system. It is shown that the problem may be cast into two possible forms, each involving an integral equation the solution of which describes the locations and spectral content of all sources. One of these integral equations is time independent and consists exclusively of deterministic quantities. The other equation is time dependent, consists of stochastic as well as deterministic quantities, and contains considerably more detail. Approximate solutions to the second equation enable one to study image undulations as explicit functions of time. Examples are presented which illustrate some of the difficulties induced by the medium fluctuations when one attempts to solve the basic integral equations.
Show PACS
43.60.Cg Statistical properties of signals and noise
43.20.Bi Mathematical theory of wave propagation

Normal short‐latency electrophysiological filtered click responses recorded from vertex and external auditory meatus

A. C. Coats, J. L. Martin, and H. R. Kidder

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 747-758 (1979); (12 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
We recorded normal electrophysiological responses to third‐octave filtered clicks from external auditory meatus (EAM) and vertex electrodes referred to coupled earlobe electrodes (forehead ground). From both vertex and EAM, polarity‐sensitive responses predominated at low frequencies and exhibited characteristics of both phase‐locked neural responses (frequency‐following response or FFR) and cochlear microphonics (CM). The FFR‐like response predominated at the vertex site and the CM‐like response predominated at EAM. At high frequencies, polarity‐insensitive responses closely resembled rectangular‐pulse click action potentials and brainstem evoked potentials, with clearly defined N1 and V peaks recorded from EAM and vertex, respectively. As frequency was lowered, the N1 and V peak latencies increased, the peaks broadened, and the latency‐intensity curves steepened with greater prolongation occurring at lower click intensities. Lowering click frequency also shortened the N1–V interval and caused the plot of N1–V interval versus click intensity to become steeper. Plots of polarity‐insensitive response amplitudes and thresholds against frequency revealed a high‐frequency bias for both N1 and V, but the V ’’frequency response’’ was flatter. A possible explanation of the shortened N1–V interval at low click frequencies based on this flatter V ’’frequency response’’ is presented.
Show PACS
43.64.Ri Evoked responses to sounds
43.64.Pg Electrophysiology of the auditory nerve

Permeability of fluid flow through hair cell cilia

Glenn H. Frommer and Charles R. Steele

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 759-764 (1979); (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Models (∠400×) were constructed of the one row of inner hair cell cilia bundles and the three row array of ’’w’’ shaped outer hair cell cilia bundles found in the mammalian cochlea. These were placed between parallel plates simulating the under surface of the tectorial membrane and the upper surface of the reticular lamina. The pressure required to produce a given volume of flow through the obstacles was measured. For low flow rate, the behavior is linear, i.e., the ratio of flow rate to pressure drop (permeability) is independent of flow rate. For higher flow rates (Reynold’s number Λ?0.08) the behavior is nonlinear, characterized by an increase in the effective permeability to a maximum at Λ∠10 and an asymmetry in the flow through the OHC cilia bundles. Interpretation in terms of cochlear function is beyond the scope of the present work. A very tentative estimate places the onset of nonlinearity at around 80 dB SPL, so the flow around the cilia bundles in the cochlea is linear for normal intensity levels.
Show PACS
43.64.Bt Models and theories of the auditory system
43.64.Dw Anatomy of the cochlea and auditory nerve
43.64.Kc Cochlear mechanics

Psychophysical tuning curves: Restricting the listening band to the signal region

David Johnson‐Davies and Roy D. Patterson

J. Acoust. Soc. Am. Volume 65, Issue 3, pp. 765-770 (1979); (6 pages) | Cited 18 times

Full Text: | Download PDF

Show Abstract
Psychophysical tuning curves were generated for three listeners by determining threshold for a 2.0‐kHz sinusoid fixed at 20 dB SPL as a function of the level and frequency of a narrow‐band noise masker. Then the listening band available to the listeners was restricted by inserting a low‐level (?18 dB SPL) stationary masker at 1.8 kHz. The stationary masker alone did not mask the signal but it depressed the upper branch of the tuning curve by as much as 20 dB. The lower branch of the curve was essentially unaffected. When the low‐level stationary masker was repositioned to 2.2 kHz the effect was reversed; the lower branch of the tuning curve was depressed but the upper branch was little changed. The combined results show that the thresholds on the two branches of the tuning curve are based on information in different frequency regions and indicate that even at reasonably low signal levels the traditional psychophysical tuning curve overestimates the frequency selectivity of the ear.
Show PACS
43.66.Ba Models and theories of auditory processes
43.66.Cb Loudness, absolute threshold
43.66.Dc Masking
43.66.Fe Discrimination: intensity and frequency
Page 1 of 5 Pages Next Page | Jump to Page
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close