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

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Next Issue

Jan 1984

Volume 75, Issue 1, pp. 1-310

Page 1 of 6 Pages Next Page | Jump to Page

Smoothed boundary conditions, coherent low‐frequency scatter, and boundary modes

I. Tolstoy

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 1-22 (1984); (22 pages) | Cited 9 times

Full Text: | Download PDF

Show Abstract
Low‐frequency coherent scatter from a rough surface may be conveniently investigated using a linear boundary condition applied to a smoothed surface, of the form ∂ϕs/∂z=ηϕ, where ϕ, ϕs are solutions of the wave equation representing, respectively, the total and scattered field potentials. The validity of the theories discussed here is restricted to kh≲1, where k is the wavenumber and h the mean spacing between roughness elements. The constant η is a function of frequency, angle of incidence, and type of roughness; in the general case of scatterers distributed isotropically over an interface between two fluids it is sensitive to eight physical parameters. Methods of calculating η for various types of rough boundary are discussed, and comparisons are made—notably between the boss and the stochastic perturbation models. Also examined are interesting implications of the smoothed boundary conditions; e.g., the boundary wave which is a true propagating mode corresponding to energy trapped in the vicinity of a rough surface, and which is only generated by a source near this surface (it thus differs fundamentally from the evanescent modes of a diffraction grating which may be excited by plane waves and are therefore not true boundary modes). For source and receiver near the boundary, and for negligible incoherent scatter, the farfield amplitude of the boundary wave may exceed that of the direct (normal) acoustic arrival—a fact which has been verified experimentally in model work. Incoherent scatter introduces an attenuation factor exp(−δr), where r is the source–receiver distance and δ is proportional to the sixth power of the frequency.
Show PACS
43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.20.Bi Mathematical theory of wave propagation
43.30.Hw Rough interface scattering
68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties

Matrix viscosity and cavity‐size distribution effects on the dynamic effective properties of perforated elastomers

G. C. Gaunaurd and J. Barlow

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 23-34 (1984); (12 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
The study presented here introduces a novel methodology to predict the (frequency‐dependent) effective material parameters characterizing the dynamic behavior of viscoelastic substances containing many randomly located air‐filled perforations. These composite materials have uses as underwater sound absorbers. The methodology described here is an extension of our earlier work which pertains to the case of gas‐filled perforations in nonabsorbing matrices. [G. Gaunaurd and H. Überall, J. Acoust. Soc. Am. 71, 282–295 (1982)]. That prior work was extended here to the case of absorbing matrices containing ensembles of cavities of various sizes following several arbitrary size‐distribution functions. The method accounts for the effect of resonances, for arbitrary levels of viscosity, for arbitrary cavity‐size distributions, and it is fundamental insofar as it generates direct predictions accounting for all these effects starting straight from the basic principles of Continuum Mechanics. Computer codes to implement the model predictions were generated, and a large number of pertinent plots of the frequency dependence (at fixed concentrations) or of the concentration dependence (at fixed frequencies) of the various effective moduli and other material descriptors have been computed and displayed in many graphs. Under various conditions the present results reduce to many of the earlier results available in the literature which serve as checkpoints. The various plots generated here pertain to various chosen cavity‐size distribution functions and to various selected levels of (dilatational and shear) absorption in the matrix. The generation and display of graphs such as these permit the present analysis of these matrix‐viscosity and size‐distribution effects mentioned in the title.
Show PACS
43.35.Mr Acoustics of viscoelastic materials
43.20.Bi Mathematical theory of wave propagation
43.20.Hq Velocity and attenuation of acoustic waves
43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants

The transition matrix for acoustic and elastic wave scattering in prolate spheroidal coordinates

Roger H. Hackman

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 35-45 (1984); (11 pages) | Cited 4 times

Full Text: | Download PDF

Show Abstract
A spheroidal‐coordinate‐based transition matrix is derived for acoustic and elastic wave scattering. The formalism is based on Betti’s third identity and an appropriately chosen set of vector spheroidal basis functions. Transition matrices are obtained for the scattering from an elastic inclusion in an elastic medium and in an inviscid fluid.
Show PACS
43.20.Fn Scattering of acoustic waves
62.30.+d Mechanical and elastic waves; vibrations
43.20.Bi Mathematical theory of wave propagation

Geometrical theory of diffraction by an open rectangular box

Pranab Saha and Allan D. Pierce

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 46-49 (1984); (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Predictions based on the geometrical theory of diffraction for sound radiation from a source within an open rigid rectangular box are compared with a set of experimental and numerical results obtained by Furue, Terai, and Matsu’ura (9th International Congress of Acoustics, Madrid, Spain, July 1977). The comparison with the experimental results shows a substantial verification of the theory.
Show PACS
43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation

Diffraction of waves and singular stresses in a soft ferromagnetic elastic solid with two coplanar Griffith cracks

Y. Shindo

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 50-57 (1984); (8 pages)

Full Text: | Download PDF

Show Abstract
Magnetoelastodynamic stress intensity factors are computed for diffraction of normally incident longitudinal waves by two coplanar Griffith cracks in a soft ferromagnetic elastic solid. The solid is permeated by a uniform magnetostatic field normal to the crack surface. The problem is formulated by means of integral transforms, and reduced to the solution of a singular integral equation of the first kind. Numerical calculations are carried out and stress intensity factors are obtained for several values of frequency, magnetic field, and geometrical parameter.
Show PACS
43.20.Fn Scattering of acoustic waves
43.40.At Experimental and theoretical studies of vibrating systems
75.80.+q Magnetomechanical effects, magnetostriction
43.35.Rw Magnetoacoustic effect; oscillations and resonance

Acoustical wave propagation in cylindrical ducts: Transmission line parameter approximations for isothermal and nonisothermal boundary conditions

Douglas H. Keefe

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 58-62 (1984); (5 pages) | Cited 21 times

Full Text: | Download PDF

Show Abstract
Approximate expressions are given for the characteristic impedance and propagation wavenumber for linear acoustic transmission through a gas enclosed in a rigid cylindrical duct. These expressions are most complicated in the transition zone where the thermoviscous boundary layers are on the order of the tube radius. The approximations are accurate to within 1% for all frequencies and tube diameters except within the transition zone where the approximations are accurate to within 10%. A simple modification of the transmission line parameters is presented for the case where the tube walls are nonisothermal.
Show PACS
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Bi Mathematical theory of wave propagation

A temperature correlation for the radiation resistance of a thick‐walled circular duct exhausting a hot gas

J. R. Mahan, J. G. Cline, and J. D. Jones

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 63-71 (1984); (9 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
It is often useful to know the radiation impedance of an unflanged but thick‐walled circular duct exhausting a hot gas into relatively cold surroundings. The reactive component is shown to be insensitive to temperature, but the resistive component is shown to be temperature dependent. A temperature correlation is developed permitting prediction of the radiation resistance from a knowledge of the temperature difference between the ambient air and the gas flowing from the duct, and a physical basis for this correlation is presented.
Show PACS
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.58.Bh Acoustic impedance measurement

Frequency domain method for the prediction of the ultrasonic field patterns of pulsed, focused radiators

Wesley N. Cobb

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 72-79 (1984); (8 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
A theoretical model is presented which can be used to calculate the pressure field patterns of pulsed, focused ultrasonic radiators in attenuating and nonattenuating media. Pressure pulses are calculated by superimposing continuous wave solutions at discrete frequencies. Due to the speed of the method, time signals can be calculated at many positions in the transducer beam in a reasonable amount of time. To test the model, theoretical predictions for the pressure signals are compared to hydrophone measurements for a conventional diagnostic transducer. In addition, signal envelopes are studied in order to determine the effects of attenuation and dispersion on the imaging characteristics of a focused radiator. This work may have significant application to the design of transducers for specific imaging purposes or to the analysis of the imaging process.
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

An analytical model for noise generated by axial oscillations of unbaffled cylindrical elements

N. Duke Perreira and Daniel Dawe

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 80-87 (1984); (8 pages)

Full Text: | Download PDF

Show Abstract
A simple method to predict the noise generated by cylindrical‐shaped machine elements in axial vibration is presented. An approximation of the Helmholtz integral equation valid when the receiver–source distance is much greater than either the cylinder’s diameter or length is used to determine the acoustic pressure generated by axial oscillations of cylinders at any aspect ratio or frequency. The results are used in developing free‐field and reverberent field design contours. Experimental evidence points to the validity of the prediction model. Included are two design problems and solutions that show the method can be used to reduce noise generated by cylindrical shaped bodies.
Show PACS
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.50.Ed Noise generation
43.40.Ey Vibrations of shells

The acoustic radiation force on a heated (or cooled) rigid sphere—Theory

Chun P. Lee and Taylor G. Wang

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 88-96 (1984); (9 pages)

Full Text: | Download PDF

Show Abstract
A finite amplitude sound wave can exert a radiation force on an object due to second‐order effect of the wave field [L. V. King, Proc. R. Soc. London, Ser. A 147, 212–240 (1934)]. In this work we study the radiation force on a rigid small sphere (i.e., in the long wavelength limit), which has a temperature different from that of the environment. This investigation assumes no thermally induced convection and is relevant to material processing in the absence of gravity. Both isotropic and nonisotropic temperature profiles are considered. In this calculation the acoustic effect and heat transfer process are essentially decoupled because of the long wavelength limit. The heat transfer information required for determining the force is contained in the parameters which are integrals over the temperature distribution.
Show PACS
43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves
43.25.Qp Radiation pressure

Acoustic streaming in a waveguide with slowly varying height

Charles Thompson

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 97-107 (1984); (11 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
An analysis of acoustic streaming in a two‐dimensional waveguide having slowly varying height is presented. Special attention is paid to waveguides with cross sections that are small compared to the acoustic and/or wall wavelengths. It is shown that the dynamic behavior of the enclosed fluid can be parameterized by the values of three small parameters, ϵ, 1/S, and 1/R, where ϵ is the ratio of the typical duct height H0 to the wall wavelength L0, 1/S is the ratio of the typical oscillatory particle displacement U0/ω to the typical duct height H0 and 1/R is the ratio of the oscillatory boundary layer thickness lν to the typical duct height H0. An analytical solution describing the streaming flow in the duct is given in terms of a regular perturbation sequence in ϵ. It is shown that the oscillatory pressure must satisfy the lossy Webster horn equation to O(ϵ2) if the no slip boundary condition is to be satisfied. Outside the boundary layer it is shown that the time averaged slip velocity is the sum of two terms. The first term is proportional to the product of the incident and reflected wave amplitudes. The second term is proportional to the difference between the incident and reflected acoustic intensity of the wave. For small values of 1/S, 1/R, and ϵ the streaming solution given is shown to be valid until ϵR/S2 becomes of O(1).
Show PACS
43.25.Nm Acoustic streaming

Acoustic streaming due to an oscillatory source near a plate

C.‐Y. Wang

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 108-111 (1984); (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
High‐frequency oscillations of a source cause an oscillatory flow near a flat plate. In addition, a nonlinear steady flow is also generated by viscous interactions. The problem is solved by matched asymptotic expansions. It is shown that a strong steady toroidal recirculation cell exist around the unsteady source.
Show PACS
43.25.Nm Acoustic streaming
43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves

Sound‐speed profile sensitivity of deep‐ocean multipath receptions

P. Bilazarian, W. L. Siegmann, and M. J. Jacobson

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 112-124 (1984); (13 pages)

Full Text: | Download PDF

Show Abstract
The sensitivity of oceanic sound transmissions to the choice of a sound‐speed profile is analyzed using ray theory. The profile may be any one from a collection of depth‐dependent, single‐minimum profiles which can be used to model a deep‐ocean sound channel. Several configurations are considered with fixed source and receiver, separated by less than about 50 km, so that different types of ray propagation can occur. Given a specified profile, procedures are prescribed for constructing a simpler profile, for which all important acoustic quantities are either identical or negligibly different. The construction methods have physical interpretations and identify the critical aspects of profile data which influence transmissions. The ray geometries associated with the two profiles are shown to be very close. Useful formulas are presented which demonstrate that per‐ray phases and amplitudes corresponding to the simpler profile approximate accurately those of the specified profile. The total‐field phase and amplitude differences associated with the two profiles are discussed briefly. Thus, when our procedure is applied, propagation results are not sensitive to the type of profile selected.
Show PACS
43.30.Es Velocity, attenuation, refraction, and diffraction in water, Doppler effect
43.30.Cq Ray propagation of sound in water
43.20.Dk Ray acoustics
92.10.Vz Underwater sound

The coherent Green’s function for acoustic propagation in a random ocean

David R. Palmer

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 125-132 (1984); (8 pages)

Full Text: | Download PDF

Show Abstract
We have derived an algorithm for calculating the coherent Green’s function of an acoustic wave propagating in an ocean possessing index‐of‐refraction fluctuations. This function is related to the so‐called strength parameter which can be used to characterize the statistics obeyed by the acoustic field. Since we are interested in a wave solution we do not make the geometric optics approximation. Consequently, it is necessary to generalize the usual form of the Markov approximation. This is done in analogy with Dashen’s investigations. Our analysis accounts for the ocean boundaries and the depth dependence of the mean index of refraction. It is, however, restricted to convergence zone propagation. The phenomenological model of internal waves introduced by Garrett and Munk is used to describe the random fluctuations in the index of refraction. The analysis is based on the use of a Feynman path integral. The path integral formalism is particulary well suited to the approximations we consider. The algorithm consists of solving the parabolic equation using the split‐step Fourier algorithm technique with an effective index of refraction term. The presence of the internal wave fluctuations are reflected in this term through an imaginary piece which attenuates the coherent Green’s function.
Show PACS
43.30.Bp Normal mode propagation of sound in water
41.20.Jb Electromagnetic wave propagation; radiowave propagation
92.10.Vz Underwater sound
43.20.Bi Mathematical theory of wave propagation

Acoustic studies of broadband scattering from a model rough surface

Peter D. Thorne and Nicholas G. Pace

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 133-144 (1984); (12 pages)

Full Text: | Download PDF

Show Abstract
Experimental measurements of the normal incidence underwater acoustic backscatter from a model rough surface having Gaussian statistics with a rms height 0.22 cm and a correlation length 1.9 cm are presented. Scattering measurements were obtained over the frequency range 20–1200 kHz for a variety of transmitter and receiver distances from the model surface. A novel feature of the experiment was the use of a parametric array as the wideband, highly directional acoustic source. An important aspect of the study is the use of a Fresnel phase approximation in the development of the theoretical expressions; this approach allows an understanding of the range dependence of the scattering coefficients. Theoretical and experimental values of the normal incidence scattering coefficients show good agreement over the range of frequencies and transmitter/receiver distances employed.
Show PACS
43.30.Bp Normal mode propagation of sound in water
43.30.Hw Rough interface scattering
43.30.Qd Global scale acoustics; ocean basin thermometry, transbasin acoustics
43.25.Lj Parametric arrays, interaction of sound with sound, virtual sources

The spatial coherence of sound scattered from a wind‐driven surface: Comparison between experiment, Eckart theory, and the facet‐ensemble method

Wayne A. Kinney and C. S. Clay

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 145-148 (1984); (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Clay and Medwin [J. Acoust. Soc. Am. 47, 1419–1429 (1970)] performed an experiment in which they measured the spatial coherence of signals scattered from a wind‐driven surface in a water tank. The coherence values were obtained by cross‐correlating signals received at two hydrophones and were presented as a function of receiver separation. In this paper, a comparison is provided between these measured values and values predicted using (1) a technique based on Eckart theory [C. S. Clay, J. Geophys. Res. 71, 2037–2046 (1966)] and (2) the facet‐ ensemble method [W. A. Kinney et al., J. Acoust. Soc. Am. 73, 183–194 (1983)]. The former technique is presented by way of a review and provides an approximate single‐valued estimate of coherence independent of receiver separation. The facet‐ensemble method, on the other hand, provides precise estimates that are fully dependent on geometry. Agreement between the method and the experiment is good.
Show PACS
43.30.Hw Rough interface scattering
43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation

Underwater sound generation by breaking wind waves

Bryan R. Kerman

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 149-165 (1984); (17 pages) | Cited 9 times

Full Text: | Download PDF

Show Abstract
The problem of identifying the source of wind‐generated underwater sound is reviewed. Amalgamated observations of the ambient noise reveal a similarity structure, both in the acoustical spectrum and wind dependency, which allows for a considerable simplification of the problem. Mechanisms of sound generation are discussed with particular reference to oscillating bubbles. Air entrainment by breaking waves and the probabilistic distribution of bubbles are discussed. A model for underwater noise generation by bubbles oscillating in a breaking wave is proposed. It is argued that the most intense sound is associated with bubbles the radius of which is comparable to the Kolmogorov scale length. A slight three‐eighths wind dependency is predicted for the frequency of the maximum intensity. Several arguments, one based on the number density of bubbles in a breaking wave, another based on the areal coverage of whitecaps, lead to the deduction that the sound intensity from a field of breaking waves varies as friction velocity to the three‐halves power. Agreement in structure and order of magnitude is demonstrated.
Show PACS
43.30.Lz Underwater applications of nonlinear acoustics; explosions
43.30.Nb Noise in water; generation mechanisms and characteristics of the field
92.10.Vz Underwater sound

Response of elastic cylinders to convective flow noise I. Homogeneous, layered cylinders

S. H. Francis, M. Slazak, and J. G. Berryman

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 166-172 (1984); (7 pages)

Full Text: | Download PDF

Show Abstract
One of the noise mechanisms experienced by passive towed sonar arrays is that of convective flow noise due to boundary layer turbulence generated as the array moves through the water at a fixed tow speed. The purpose of the present work is to arrive at quantitative predictions of the effects of convective flow noise using relatively simple model calculations. Line arrays are modeled as homogeneous, layered cylinders while turbulent eddies are modeled as random pressure fluctuations traveling at the convective speed of the eddies (about 80%) of the tow speed. The qualitative difference between solid and liquid fills is explained with this analysis. Solid‐filled arrays are more susceptible to convective flow noise than are liquid‐filled arrays because the noise‐carrying shear waves are highly attenuated in the liquid. The detailed analysis is presented both for homogeneous cylinders and for cylinders with multiple homogeneous layers. Examples are presented to illustrate the analysis and the numerical methods employed in the calculations.
Show PACS
43.30.Nb Noise in water; generation mechanisms and characteristics of the field
43.30.Lz Underwater applications of nonlinear acoustics; explosions
47.27.nb Boundary layer turbulence
43.35.Mr Acoustics of viscoelastic materials

Measurements on the origin of the wind‐dependent ambient noise variability in shallow water

Peter C. Wille and Detlef Geyer

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 173-185 (1984); (13 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
Contributions of environmental quantities related to the noise source field and the propagation path are derived from the comparison of measurements of the wind‐dependent noise by omnidirectional receivers at a fixed North Sea station with shipborne measurements in the Baltic Sea. The influence of propagation loss on the wind‐dependent shallow water noise appears to be only marginal, even at extremely different sea areas. The quantity governing the noise spectrum level under uncontaminated conditions is the wind speed at the sea surface for which the second power law relation has been verified between 50 Hz and 20 kHz and above a ‘‘threshold’’ wind speed of ≊5 kts. Neither the characteristic height of the sea waves nor the wind turbulence at the reference height are relevant to the noise production, but both may indicate wind profile changes which originate an essential portion of the noise variability for a given wind speed. Further deviations from the second power law are attributed to a bubble layer effect under storm conditions reducing or enhancing the high frequency noise level thus yielding a spread of the average spectrum level of more than 20 dB.
Show PACS
43.30.Nb Noise in water; generation mechanisms and characteristics of the field
43.30.Lz Underwater applications of nonlinear acoustics; explosions
92.10.Kp Sea-air energy exchange processes

Theoretical prediction of a backscattering maximum at Rayleigh angle incidence for a smooth liquid–solid interface

Tran D. K. Ngoc and Walter G. Mayer

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 186-188 (1984); (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
A numerical integration method for the description of acoustic bounded beams is used to calculate possible backscattering strength from a smooth liquid–solid interface. It is shown that the backscattering strength is maximum for Rayleigh angle incidence. The influence of beam shape and beamwidth on the backscattering strength near the maximum is demonstrated.
Show PACS
43.35.Pt Surface waves in solids and liquids
68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties
43.20.Bi Mathematical theory of wave propagation
43.20.Fn Scattering of acoustic waves

An experimental study of interaction between surface waves and a surface breaking crack

C. H. Yew, K. G. Chen, and D. L. Wang

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 189-196 (1984); (8 pages) | Cited 2 times

Full Text: | Download PDF

Show Abstract
The interaction between surface waves and a surface breaking crack is studied experimentally. In this study, the surface wave is generated by dropping a small ball on the long side of a large plate. The wave motions are monitored on both sides of the crack with a pair of piezoelectric transducers. Upon analyzing the results, we have found that: (1) the arrival time of different wave components to the recording transducer placed on the forward side of the crack may be estimated by regarding the crack tip as a buried source to each impinging wave components; and (2) the depth of the crack may be estimated by comparing the amplitude spectra of the wave motions recorded on both sides of the crack.
Show PACS
43.35.Pt Surface waves in solids and liquids
68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties
46.50.+a Fracture mechanics, fatigue and cracks
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products

Modeling time‐delay measurement errors using a generalized beta density function

Joseph J. Perruzzi and E. J. Hilliard, Jr.

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 197-201 (1984); (5 pages)

Full Text: | Download PDF

Show Abstract
A four‐parameter beta density function is employed to model time‐delay measurement errors associated with sensor data used in triangulation ranging. This generalized density function allows considerable flexibility in modeling the pertinent error statistics. Specifically, assigning appropriate values to the parameters lead to other symmetric beta, skewed beta, or uniform distributions, all of which can be biased or zero mean. Exploiting a variety of modeling possibilities through parameter selection imparts more realism to the modeling process. The triangulation range density function along with its mean and standard deviation are derived. Comparisons of the pertinent range statistics are made for different measurement error models. Finally, the range statistics associated with the symmetrical beta density function are compared in detail with those statistics obtained from the uniform density function for equivalent values of time‐delay measurement error standard deviation.
Show PACS
43.60.Gk Space-time signal processing, other than matched field processing
43.30.Tg Navigational instruments using underwater sound

Responses of pigeon vestibular nerve fibers to sound and vibration with audiofrequencies

H. P. Wit, J. D. Bleeker, and H. H. Mulder

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 202-208 (1984); (7 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
Single unit recordings were made from the nerve branch innervating the crista in the horizontal semicircular canal of a pigeon. The vestibular organ was either stimulated with sound through the ear canal or with a vibrator in contact with the membraneous ampulla roof. Units responding to sound or vibration showed tuning with a best frequency of approximately 0.7 kHz. The average low‐frequency slope of the tuning curves is −16 dB/oct; the average high‐frequency slope 20 dB/oct. The threshold amplitude for vibrator stimulation is 30 nm. This value comes close to the calculated threshold value for cupula deflection in the human semicircular canal.
Show PACS
43.64.Pg Electrophysiology of the auditory nerve
43.64.Tk Physiology of sound generation and detection by animals
43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing

Growth rate of loudness, annoyance, and noisiness as a function of tone location within the noise spectrum

Rhona P. Hellman

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 209-218 (1984); (10 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
The relation between overall perceived magnitude (loudness, annoyance, and noisiness) of noise‐tone complexes and the location of the tone within the spectrum was investigated by absolute magnitude estimation (AME). Single tones at 250, 1000, 2000, and 3000 Hz were added to low‐ and high‐pass noises. In contrast to noisiness, loudness and annoyance growth behavior depends on the relationship between the frequency of the added tone and the spectral shape of the noise. Tones centered in noise produce nonmonotonic loudness and annoyance growth functions; those added to the skirt produce power functions. The measured exponents are invariant across tone‐to‐noise ratio when the tones are positioned within the spectrum, but not when they are added to the skirt. Moreover, for complexes at approximately the same overall SPL, the tone’s position determines the functional relationship between loudness (or annoyance) and tone‐to‐noise ratio. Although a tone correction for annoyance is warranted for certain noise‐tone configurations, none of the proposed calculation procedures considers all the variables relevant to perceived annoyance of tonal components. To a large extent, complex auditory interactions generated by the simultaneous presentation of noise and tone can account for the observed effects.
Show PACS
43.66.Cb Loudness, absolute threshold
43.66.Dc Masking
43.50.Ba Noisiness: rating methods and criteria

Dependence of post‐masking on masker duration and its relation to temporal effects in loudness

Eberhard Zwicker

J. Acoust. Soc. Am. Volume 75, Issue 1, pp. 219-223 (1984); (5 pages) | Cited 8 times

Full Text: | Download PDF

Show Abstract
Temporal masking of tones by noise was investigated using a post‐ (forward‐) masking paradigm. The masker level and duration were varied. For every masker level employed, the rate of decay of masking was found to depend on the duration of the masker. Specific loudness values were computed from the forward masking functions and an electronic device which simulates these loudness functions is presented. In the simulation, a series of integrators or a single integration with one long time constant was utilized. The effect of the proposed integrators on loudness meters is discussed.
Show PACS
43.66.Dc Masking
43.66.Cb Loudness, absolute threshold
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
Page 1 of 6 Pages Next Page | Jump to Page
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close