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Journal of the Acoustical Society of America

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Jun 1980

Volume 67, Issue 6, pp. 1865-2139

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Acoustics of gas‐bearing sediments I. Background

Aubrey L. Anderson and Loyd D. Hampton

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1865-1889 (1980); (25 pages) | Cited 20 times

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Acoustical properties of water saturated and gassy sediments are observed to be significantly different. The present state of knowledge of the acoustical properties of saturated sediments, gassy water, and gassy sediments is reviewed. The dynamics of bubbles in water and in various solid materials, including sediments, are experimentally examined in a companion paper. Pulsation resonance is exhibited by the bubbles in all materials examined. Predictions of bubble resonance frequency and damping are shown to agree with the measurements. Equations for sound speed and attenuation, based on the model of resonating gas bubbles, are shown to agree with published measurements in gassy sediments. Parameters required for predicting gassy sediment acoustical properties are identified. Ranges of values of these parameters for various sediments are discussed.
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43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.35.Bf Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in liquids, liquid crystals, suspensions, and emulsions
43.30.-k Underwater sound

Acoustics of gas‐bearing sediments. II. Measurements and models

Aubrey L. Anderson and Loyd D. Hampton

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1890-1903 (1980); (14 pages) | Cited 13 times

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Acoustical properties of water saturated and gassy sediments are observed to be significantly different. The present state of knowledge of the acoustical properties of saturated sediments, gassy water, and gassy sediments is reviewed in a companion paper. The dynamics of bubbles in water and in various solid materials, including sediments, are experimentally examined here. Pulsation resonance is exhibited by the bubbles in all materials examined. Predictions of bubble resonance frequency and damping are shown to agree with the measurements. Equations for sound speed and attenuation, based on the model of resonating gas bubbles, are shown to agree with published measurements in gassy sediments. Parameters required for predicting gassy sediment acoustical properties are identified. Ranges of values of these parameters for various sediments are discussed.
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43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.35.Bf Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in liquids, liquid crystals, suspensions, and emulsions
43.30.-k Underwater sound

Scattering by a smooth elastic obstacle

Anders Boström

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1904-1913 (1980); (10 pages) | Cited 3 times

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In the present paper we adapt the transition matrix method to the case of a smooth elastic obstacle. The boundary conditions employed are discussed in some detail and are seen to be responsible for the fact that the rather complicated formal solution in many respects resembles that for an elastic obstacle in a fluid. Comparisons are made between the smooth and the usually employed welded obstacles, and for spheres approximate expressions are given for the transition matrices in the long wavelength limit. Numerical results (cross sections and surface stresses) are given for spheres and spheroids, and it is then seen that often the smooth and welded obstacles, at least qualitatively, show similar features.
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43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation
43.40.At Experimental and theoretical studies of vibrating systems

Acoustic propagation in rigid sharp bends and branches

Michael El‐Raheb and Paul Wagner

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1914-1923 (1980); (10 pages) | Cited 2 times

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The linear acoustic propagation in rigid planar sharp bends and bifurcation ducts is analyzed using a Green’s‐function integral technique often known as the surface element method. The acoustic characteristics of the sharp bend differ substantially from those of a circular bend with identical turning angle, width, and centerline length. The acoustic loading resulting from a duct bifurcation is highly two dimensional beyond the first cutoff frequency.
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43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Bi Mathematical theory of wave propagation
43.20.Ks Standing waves, resonance, normal modes

Acoustic propagation in rigid three‐dimensional waveguides

Michael El‐Raheb

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1924-1930 (1980); (7 pages) | Cited 2 times

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The linear acoustic propagation in finite rigid three‐dimensional waveguides is determined analytically using an eigenfunction expansion of the Helmholtz equation. The geometry considered consists of straight and circular bends of rectangular cross section with continuous interfaces (branches and sharp corners are excluded). The phenomena of resonance shift and relocation are explained for a bend–straight duct combination.
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43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Bi Mathematical theory of wave propagation
43.20.Ks Standing waves, resonance, normal modes

Mode selective transfer of energy from sound propagating inside circular pipes to pipe wall vibration

E. J. Kerschen and J. P. Johnston

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1931-1934 (1980); (4 pages)

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Experimental results are presented which show a mode selective transfer of energy from sound propagating inside a circular pipe to pipe wall vibration. The experiments utilize broadband noise generated by flow through a restriction in the plastic (PVC) pipe. For each higher acoustic duct mode, the energy transfer occurs in a narrow frequency band located slightly above the higher‐mode cut‐on frequency. A match in axial phase velocity between the higher acoustic duct mode and a compatible pipe wall vibrational mode is proposed as the mechanism for the energy transfer. Theoretical predictions for the frequency at which the axial phase velocity match occurs show good agreement with the experimental results.
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43.20.Mv Waveguides, wave propagation in tubes and ducts
43.40.Ey Vibrations of shells
43.20.Tb Interaction of vibrating structures with surrounding medium

Output of acoustical sources

Harold Levine

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1935-1946 (1980); (12 pages) | Cited 3 times

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Acoustic radiation from a source, here viewed as an immobile point singularity with periodic strength and a given multipolar nature, is affected by the presence of nearly structural elements (e.g., rigid or impedance surfaces) as well as that of a background flow in the medium. An alternative to the conventional manner of calculating the net source output by integrating the energy flux over a distant control surface is described; this involves a direct evaluation of the secondary wavefunction at the position of the primary source and obviates the need for a (prospectively difficult) flux integration. Various full and half‐planar surface configurations with an adjacent source are analyzed in detail, and the explicit result obtained, in particular, for the power factor of a dipole brings out a substantial rise in its output as the source nears the sharp edge of a half‐plane.
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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

Reflection and transmission of plane elastic waves at the boundary between piezoelectric materials and water

Behzad Noorbehesht and Glen Wade

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1947-1953 (1980); (7 pages) | Cited 2 times

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See Also: Erratum

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Reflection and transmission coefficients for plane elastic waves obliquely incident on the boundary between two isotropic materials have been known for some time. The solution for anisotropic materials, however, has not been fully treated in the literature. Here we derive these coefficients for the case of a piezoelectric ceramic in contact with water. This problem is of significant practical interest, since in a variety of applications, piezoelectric ceramics, which are inherently anisotropic, are used as transducers to radiate acoustic energy into water. Due to the anisotropy, velocities of both compressional and shear waves are functions of the angle of incidence. Piezoelectric equations are solved to find the variations of compressional and shear wave velocities with the angle of incidence. Reflection and transmission coefficients are then obtained and numerical results are presented for four piezoelectric ceramics.
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43.20.Bi Mathematical theory of wave propagation
43.20.Fn Scattering of acoustic waves
62.30.+d Mechanical and elastic waves; vibrations
43.38.Fx Piezoelectric and ferroelectric transducers

Frequency approach to nonlinear dispersive waves

A. Korpel

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1954-1958 (1980); (5 pages) | Cited 1 time

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Coupled equations are derived which describe the evolution of harmonic content for quadratic nonlinearity in the presence of arbitrary attenuation and dispersion. The equations are shown to be in agreement with known results of nonlinear acoustics and to describe novel phase locking and parametric phenomena when applied to dispersive systems. They are well suited to a planned computer analysis concerning the existence of solitary waves in systems with topological dispersion.
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43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves
43.25.Ed Effect of nonlinearity on velocity and attenuation

The propagation of thunder through the atmosphere

H. E. Bass

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1959-1966 (1980); (8 pages)

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The status of current research into the relations between thunder and the lightning process is examined. Nonlinear effects near the discharge strongly influence the pressure waveform and hence the nearfield acoustic spectrum. At distances where measurements are typically made, propagation effects strongly influence the shape of the recorded spectrum. Since most measurements do not reliably determine propagation distances or the physical characteristics of the propagation path, they are of little value in deducing the nearfield pressure waveform. Even with these problems, the gross features of thunder can be explained qualitatively and there is hope that future experiments will provide information necessary to correct for propagation effects making the study of thunder a useful tool for testing theoretical models of lightning.
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43.28.Fp Outdoor sound propagation through a stationary atmosphere, meteorological factors
43.28.Hr Outdoor sound sources
43.25.Cb Macrosonic propagation, finite amplitude sound; shock waves

Excess attenuation in echosonde signals

S. F. Clifford and E. H. Brown

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1967-1973 (1980); (7 pages) | Cited 1 time

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The scattering of sound by turbulence redistributes the acoustic energy flow in space. For sound propagation with a given geometry, such a redistribution can appear as an energy loss in the received part of a beam. Such a loss now is called excess attenuation. The following analysis determines the amount of excess attenuation in the signal obtained in the configuration of a typical monostatic echosonde. Such estimates of excess attenuation are of great importance for accurate quantitative acoustic remote sensing of atmospheric parameters.
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43.28.Py Interaction of fluid motion and sound, Doppler effect, and sound in flow ducts
43.28.Fp Outdoor sound propagation through a stationary atmosphere, meteorological factors
43.20.Fn Scattering of acoustic waves

Fan noise reduction by single‐ and double‐wall barriers

Dieter Lohmann

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1974-1979 (1980); (6 pages) | Cited 1 time

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In the case where the source of sound is a turbo‐jet engine fan the solution of Fresnel–Kirchhoff’s diffraction integral contains an additional term. That term may be neglected when the source of sound is a single harmonic point source. Formulas, including this term, show that behind a barrier the fan noise is amplified instead of being reduced. The amplification effect occurs when the rim of the barrier is located in areas of high or rather maximum sound levels. It was found out that double‐wall barriers prevent sound amplification. This additional abatement of sound in the shadow zone of the screen is partially caused by absorption of diffracted waves within the open double‐wall ’’cavity.’’ A semi‐empirical formula was developed to estimate this absorption. As basic configuration for experimental studies a DC‐10 half model with a CF6‐turbo fan engine was selected to be tested in model scale of 1 :10. All test runs were conducted in an anechoic chamber of the DFVLR, Department of Technical Acoustics, Germany. The agreement between theory and experiment is satisfactory.
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43.28.Ra Generation of sound by fluid flow, aerodynamic sound and turbulence
43.28.Fp Outdoor sound propagation through a stationary atmosphere, meteorological factors
43.50.Nm Aerodynamic and jet noise

The scattering of sound by turbulence in water

M. S. Korman and R. T. Beyer

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1980-1987 (1980); (8 pages)

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This paper describes experimental results on the scattering of sound by turbulence in water. The turbulence is created by a 1‐in.‐diam submerged water jet, nozzle velocity 648 cm/s. The sound frequency is 1 MHz. The spectral broadening of the monochromatic signal (due to the scattering of the sound by the turbulent eddies) is compared for different forward scattering angles in the case of incident plane and cylindrical waves. A theoretical model is presented to explain the plane‐wave results. Results for the scattering of cylindrical waves are compared with experiments performed by Candel and Julienne [AIAA Paper No. 76‐545, 3rd AIAA Aero‐Acoustics Conference, Palo Alto, California (July 20–23, 1976)] in air with spherical wave sources.
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43.30.Gv Backscattering, echoes, and reverberation in water due to combinations of boundaries
43.28.Py Interaction of fluid motion and sound, Doppler effect, and sound in flow ducts

Spatial correlation of surface generated noise in a stratified ocean

W. A. Kuperman and F. Ingenito

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1988-1996 (1980); (9 pages) | Cited 36 times

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A model is developed for the calculation of the spatial properties of the noise field produced in a stratified ocean by the action of wind at the surface. The random noise sources are represented by correlated monopoles distributed over an infinite plane located an arbitrary depth below the surface. Wave‐theoretical methods are applied to derive expressions for the intensity and spatial correlation of the noise field. A normal‐mode representation of the noise field is used to reduce these expressions to forms which allow physical interpretation and are suitable for numerical computation. Examples are given of intensity profiles and spatial correlation in the vertical for three generic sound‐speed profiles. The results show that the sound‐speed profile and the presence of the bottom can be important in determining the spatial properties of the noise field. An example is given of a calculation of the horizontal spatial correlation using the fast field program (FFP).
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43.30.Nb Noise in water; generation mechanisms and characteristics of the field
43.30.Cq Ray propagation of sound in water

Effect of a class of random currents on acoustic transmission in an ocean with linear sound speed

B. K. Newhall, M. J. Jacobson, and W. L. Siegmann

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 1997-2010 (1980); (14 pages)

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The effects of random fluctuations in an ocean current on underwater cw sound transmission between a bottomed source and receiver are determined for an ocean channel with a linear, depth‐dependent sound speed. A horizontal, depth‐dependent current is considered whose components are random processes. Effects of such a current on ray geometry are determined and six basic current‐induced ray states are found. Under certain conditions, including the assumption that the sound‐speed gradient is larger than current‐component gradients, only one ray state may arise. The geometry of this state is expressed explicitly in terms of the current. Approximations for travel times, total‐field intensity, and their first and second moments are obtained. These moments depend significantly on properties of the source–receiver current component. Intensity moments are predicted using ocean‐current data. For selected parameter values, a difference between relative mean intensity and relative intensity without current of as much as 9 dB and a standard deviation of relative intensity as large as 3 dB are found. These moments are rapidly varying with transmission range; however, useful bounds are derived which are slowly varying and which display an unusual behavior near certain critical ranges.
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43.30.Bp Normal mode propagation of sound in water
92.10.Vz Underwater sound

Stability and identification of ocean acoustic multipaths

John L. Spiesberger, Robert C. Spindel, and Kurt Metzger

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2011-2017 (1980); (7 pages) | Cited 11 times

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A phase‐coded signal with 64‐ms resolution was transmitted at 10‐min intervals for a 48‐day period between an acoustic source moored at 2000‐m depth and a bottom mounted receiver at ∠3000‐m depth and at ∠900‐km range. About 16 multipaths were resolved. They were stable in the presence of ocean fluctuations and could be identified (with some exceptions) from ray theory. The precision to which daily travel‐time fluctuations along multipaths could be measured was better than 10 ms. The resolution, stability, identification, and precision is adequate for acoustic monitoring of mesoscale ocean variability by measuring travel‐time variations along ray paths.
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43.30.Bp Normal mode propagation of sound in water
92.10.Vz Underwater sound
43.20.Dk Ray acoustics

Uniform asymptotic evaluation of the continuous spectrum contribution for the Pekeris model

D. C. Stickler and E. Ammicht

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2018-2024 (1980); (7 pages) | Cited 3 times

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The determination of the continuous spectral contribution to the transmission loss in ocean acoustics can be very difficult. While it is applicable to very general sound‐speed profiles, a uniform asymptotic method, i.e., one that is valid as the proper modes pass through cutoff, is proposed and illustrated for the Pekeris model. The method exploits the fact that there are singularities near the integrand of an integral representation of continuous spectrum and that these singularities determine the asymptotic behavior of the continuous spectrum. Numerical examples illustrate the influence of the proper, real improper, and complex improper modes on the continuous spectrum. The technique avoids the sometimes costly numerical evaluation of the continuous spectral contribution; however, the improper eigenvalues must be found.
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43.30.Bp Normal mode propagation of sound in water
43.30.Cq Ray propagation of sound in water
43.30.Jx Radiation from objects vibrating under water, acoustic and mechanical impedance

Measurements of underwater signal phase stability using a moving source

H. J. Young

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2025-2028 (1980); (4 pages)

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In an experiment using a cw source suspended from a drifting ship, the phase angles of the signals at four hydrophones laid on the bottom in a horizontal line were compared. The experimental technique used was a new one which canceled out the Doppler shift of the signal by using the combined outputs of all the hydrophones as a phase reference signal. This technique made it possible to compare the phase angles of signals arriving over multiple paths. The mean cosines of the phase differences were obtained as a function of separation for four pairs of hydrophones. An empirical expression was selected to fit the experimental results and permit interpolation to obtain values for other hydrophone spacings.
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43.30.Bp Normal mode propagation of sound in water
43.60.Gk Space-time signal processing, other than matched field processing
43.30.Jx Radiation from objects vibrating under water, acoustic and mechanical impedance

Method for solving vibration problems of a plate with arbitrary shape

Kosuke Nagaya

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2029-2033 (1980); (5 pages) | Cited 1 time

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This paper is concerned with a method for solving vibration problems of a thin elastic plate with arbitrary shape. The exact solution of an equation of motion is utilized and the boundary conditions along both arbitrarily shaped curved and straight line boundaries are satisfied by means of the Fourier expansion method. Numerical calculations are carried out for the clamped or simply supported elliptical and parabolic plates.
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43.40.Dx Vibrations of membranes and plates

Torsional wave propagation in an infinite piezoelectric cylinder (622) crystal class

V. R. Srinivasamoorthy and C. Anandam

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2034-2035 (1980); (2 pages)

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Torsional wave motion in an infinite right circular hollow piezoelectric cylinder belonging to (622) crystal class is investigated when the cylindrical surfaces are either traction‐free or subjected to relative displacement. Open and short‐circuit resonant frequency equations are formulated. Fundamental resonant frequency curves are given for traction‐free cylinders. The theory is applied to the vibrations of annular accelerometers.
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43.40.Ey Vibrations of shells
43.40.At Experimental and theoretical studies of vibrating systems
43.38.Fx Piezoelectric and ferroelectric transducers

Effects of noise on some autonomic system activities

Karl D. Kryter and Fausto Poza

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2036-2044 (1980); (9 pages)

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Experiments were conducted on the effects of various expected noise conditions upon autonomic system activity in men during rest and work (bicycle ergometer). Skin temperature and heart rate were not appreciably, if at all, affected by any of the noises. Wide‐band, predominantly low‐frequency noise, at a level of 92 dB, A‐weighted, generally caused a decrease in pulse amplitude (indicative of constriction of peripheral blood vessels) during either work or rest, whereas an equally intense one‐third octave band of random noise, center frequency of 3150 Hz, had no appreciable effect on pulse amplitude. Repeated exposures to the wide‐band noise showed some adaptation or habituation of the pulse amplitude response during conditions of either work or rest. The results were the same for fast rise time (impulsive) bursts of wide‐band noise as for bursts with slow, gradual onsets. Rapid interruptions of wide‐band noise caused less of a decrease in average pulse amplitude than did uninterrupted noise. It is suggested that constriction of peripheral blood vessels in response to expected intense low‐frequency or wide‐band noises is more related to auditory, reflexive protective mechanisms than to autonomic system responses generally considered to be stressful to the organism.
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43.50.Qp Effects of noise on man and society
43.80.Ev Acoustical measurement methods in biological systems and media
43.80.Gx Mechanisms of action of acoustic energy on biological systems: physical processes, sites of action

The use of quantitative criteria for the optimum design of concert halls

Donald E. Baxa and A. Seireg

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2045-2054 (1980); (10 pages)

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This paper describes a set of eight quantitative merit criteria for the design of concert halls, used in a developed automated computer optimization procedure based on a modified method of images. Idealized optimum hall configurations and surface absorption coefficients are determined based on each criterion. The acoustical merits of the optimum designs for a hall with given floor and stage areas are evaluated and compared to those of an existing hall with acclaimed acoustical quality. They are also compared to those calculated when the total sum of all the eight merit criteria is used as the optimizing objective function. The study represents a first attempt at optimizing acoustic space based on quantitative figures of merit. The developed technique can be invaluable in giving insight into the effect of improving a particular design objective on the configuration and absorption coefficients, as well as how the improvement of one merit criterion can affect the other criteria.
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43.55.Gx Studies of existing auditoria and enclosures
43.55.Fw Auditorium and enclosure design
43.55.Ka Computer simulation of acoustics in enclosures, modeling

An underwater acoustic sound velocity data model

Lester R. LeBlanc and Foster H. Middleton

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2055-2062 (1980); (8 pages) | Cited 6 times

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A computer model for generating world ocean sound velocity profile (SVP) information is presented. It employs a ’’least‐squares’’ predictor to combine National Oceanographic Data Center (NODC) archival SVP data with any amount of available new sound velocity measurements that might be available. A technique is presented in the paper for the analysis of NODC World Ocean SVP data which is highly efficient. The technique is called empirical orthonormal function (EOF) analysis and it is capable of a very large compaction of the data set. This method provides a very compact presentation of the total statistical nature of the SVP data bank. The end result is a computer model which permits the optimum utilization of all archival data and any new data at a given place and time in world oceans to produce a new complete SVP. Of even greater significance is the fact that the form of the predicted SVP profile is such that it is easily employed in any propagation loss prediction model that is currently in use.
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43.60.Gk Space-time signal processing, other than matched field processing
43.30.Cq Ray propagation of sound in water
92.10.Vz Underwater sound
43.58.Ta Computers and computer programs in acoustics

The tempered Fourier transform

Dale T. Teaney, Victor L. Moruzzi, and Frederick C. Mintzer

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2063-2067 (1980); (5 pages)

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A constant‐Q digital spectral analysis scheme is described which exploits the ’’perfect fifth’’ symmetry of the 12‐tone musical scale.
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43.60.Gk Space-time signal processing, other than matched field processing
43.75.Bc Scales, intonation, vibrato, composition

A method of calculating average array signal response in a two‐path medium

R. D. Worley

J. Acoust. Soc. Am. Volume 67, Issue 6, pp. 2068-2072 (1980); (5 pages)

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A method is described for calculating average signal array gain for cw acoustic signals in a multipath medium. The two‐path case is considered; the extension to many paths is straightforward but tedious. Only phase fluctuations are treated; the signals arriving along the two paths may have different amplitudes, but these amplitudes are assumed constant in time and uniform across the array aperture. It is suggested that for beam formation by delay and sum the array signal gain for single path represents the upper limit of performance for multipath. The calculation of gain requires a knowledge of the signal correlation across the array aperture for each path, as well as the signal correlation between the first arrival at one hydrophone and the second arrival at another as a function of hydrophone spacing.
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43.60.Gk Space-time signal processing, other than matched field processing
43.30.Bp Normal mode propagation of sound in water
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