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Journal of the Acoustical Society of America

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Sep 1961

Volume 33, Issue 9, pp. 1163-1248


Aid to Music Composition Employing a Random Probability System

Harry F. Olson and Herbert Belar

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1163-1170 (1961); (8 pages)

Online Publication Date: 26 Jul 2005

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The random probability system generates sequences of notes in a series which are not completely random nor completely ordered, but each note is selected in a random fashion with a probability which depends upon preceding notes. Combined with sound synthesizers, the machine provides additional instrumentation for the musical laboratory.

Notes on Scaling Jet and Rocket Noise

David A. Bies and Peter A. Franken

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1171-1173 (1961); (3 pages)

Online Publication Date: 26 Jul 2005

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For dynamically similar systems it is shown that pressure fluctuation amplitudes at similar positions are the same when measured in constant percentage‐frequency bands and when frequency is scaled inversely proportional to a characteristic length. This scaling relationship can be extended to systems containing acoustic liners if the linear flow resistance is held constant. Corrections for small errors in scaling are suggested for the case of rocket engines.

On Vowel Duration in English

Arthur S. House

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1174-1178 (1961); (5 pages) | Cited 12 times

Online Publication Date: 26 Jul 2005

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Average durations of 12 vowels of American English measured in bisyllabic nonsense utterances are reported. The vowels occurred in 14 symmetrical consonantal environments and the utterances were produced by three male talkers. The consonant environments consisted of the voiced and voiceless versions of three stop, one affricate, and three fricative consonant articulations. Four determinants of the characteristic durations of stressed vowels are identified and discussed. The hypothesis is advanced that the primary lengthening of vowels in English—that found in tense vowels and in vowels before voiced constants—is a part of the phonology of the language and is learned by speakers of the language, and that the secondary lengthening of vowels in English—that found in open vowels and in vowels before fricative constants—is a function of the articulatory process itself.

Korotkoff Sounds in Humans

John D. Wallace, David H. Lewis, and Sami Abou Khalil

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1178-1182 (1961); (5 pages)

Online Publication Date: 26 Jul 2005

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Direct monitoring of Korotkoff sounds from the brachial artex with vascular pressure, cuff pressure, and external sounds has been carried out. Recording of the internal sounds suggests a discrepancy between direct and indirect blood pressure measurement. Examples of spectrograms of the Korotkoff sounds near diastolic pressure are presented.

On the Realization of a Linear Graph Given Its Algebraic Specification

L. Auslander and H. M. Trent

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1183-1192 (1961); (10 pages)

Online Publication Date: 26 Jul 2005

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The following problem is discussed in this paper. Given an algebraic specification of an oriented linear graph in the form of a branch‐mesh or branch‐node matrix on any arbitrary basis, how does one proceed systematically to construct the graph? This rather basic problem has been considered by other authors and a few procedures have been described in the literature. On closer examination the problem is not simply one of finding any old procedure that will work but rather a question of finding an efficient procedure in terms of the time required by an analyst to carry through the computation. A new procedure is described which is believed to be quite efficient. This procedure is simple since matrix manipulations are limited primarily to the deletion of rows and columns and the other main manipulation is that of freehand drawing.
The procedure is based upon the Decomposition Theorem published earlier and involves the notion of dividing a large graph into a sequence of small ones. A reassembly process then yields the desired result.

Generation of Sound in Cavities by Flow Rate Changes

Peter A. Franken

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1193-1195 (1961); (3 pages)

Online Publication Date: 26 Jul 2005

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Sound generated by mass or heat flow changes in a cylindrical cavity is considered. The special case of a high‐pressure‐ratio orifice is studied. Experimental results show good agreement with values predicted from a scaling equation.

On the Theory of the Propagation of Plane, Finite Amplitude Waves in a Dissipative Fluid

William W. Lester

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1196-1199 (1961); (4 pages)

Online Publication Date: 26 Jul 2005

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The dissipationless theory for harmonic generation in an initially sinusoidal, plane, finite‐amplitude wave is used as a basis for calculation of the harmonic components of such a wave in a fluid with dissipation. The assumption used is shown to lead approximately to the relationships of the Fox and Wallace theory. The result is given as a Fourier series, with graphs of the first few harmonic components for two specific cases. The series representation is valid for distances X⩽L, where L is the discontinuity distance for the dissipationless case.

Sound Propagation over Ocean Waters in Fog

Francis M. Wiener

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1200-1205 (1961); (6 pages)

Online Publication Date: 26 Jul 2005

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Audible fog signals are extensively used as aids to marine navigation during periods of low visibility. Performance, however, has frequently been inadequate. To obtain better understanding of the physics of sound propagation over water in fog, a series of field experiments was carried out off the coast of Maine. Signals in the frequency range between about 200 and 2000 cps were employed to measure sound attenuation for distances up to a few miles. Simultaneous micrometeorological measurements were performed to describe the relevant properties of the lowest layers of the atmosphere through which the sound was propagated. This paper describes briefly the measurement techniques used and presents typical samples of the results obtained. Downwind, the average excess attenuation over and above inverse square law can be accounted for principally by molecular absorption. Upwind, large values of excess attenuation were found due to shadow zone formation. This constitutes a severe limitation of the useful range of audible fog signals. Fog itself contributes little to the average excess attenuation.

Impedance of Tapered Structures

Frederick J. Young and Beverly H. Young

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1206-1210 (1961); (5 pages)

Online Publication Date: 26 Jul 2005

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A general expression for the impedance of acoustical horns and analogous devices is derived by considering a manifold of uniform structures. The impedance of the manifold is obtained by complete mathematical induction and the impedance of a smoothly varying tapered structure is obtained by a limiting process. With the expressions established here the impedances of acoustical horns having mouth to throat area ratios ranging from 0.125 to 8 can be calculated with less than 10% error at zero frequency.

Interference Versus Frequency in Measurements in a Shallow Lake

Robert J. Bobber

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1211-1215 (1961); (5 pages)

Online Publication Date: 26 Jul 2005

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When an omnidirectional projector and hydrophone are closely spaced and in shallow water, and sound is transmitted from one to the other, a large interference signal is superimposed on the direct signal. If the received signal is plotted as a function of frequency, as in a calibration measurement, the interference signal amplitude appears to be an inconsistent series of irregular sharp peaks and dips. A mathematical analysis of the condition where the transducers are midway between a water‐air surface and a bubble‐covered bottom shows that the shape, amplitude, and frequency of the interference pattern are predictable as the result of a large number of multireflection paths.

Optimum Frequencies for Active Sonar Detection

J. L. Stewart, E. C. Westerfield, and M. K. Brandon

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1216-1222 (1961); (7 pages)

Online Publication Date: 26 Jul 2005

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The method of determination of the optimum frequencies for active sonar without knowledge of the absolute values of the sonar‐set parameters, but only of their frequency dependence, appears to have been originated by J. W. Horton in about 1945 and is to be found in his recent text. This theory has been simplified and extended to include search rate,time‐processing gain, and the ratio of echo‐to‐noise‐plus‐reverberation. The inclusion of these new factors only slightly modifies the results obtained by maximizing echo‐to‐noise ratio alone because of the dominant effect of the frequency dependent exponential attenuation term in the transmission loss. Because of the octave or greater width of the maxima and the lack of precision in the knowledge of the frequency dependencies, the optimum frequencies should be looked on only as broad regions. For longer‐range and hence lower‐frequency active sonata operating at their optimum frequencies the energy of the pulse required per unit area or volume searched increases rapidly with the design range to a high exponent for the cases considered. This corollary is probably of little practical significance since the cost of operating power is usually small compared to other costs.

Microbubble Persistence in Fresh Water

W. R. Turner

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1223-1233 (1961); (11 pages) | Cited 1 time

Online Publication Date: 26 Jul 2005

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Preliminary research confirms that microbubbles become stabilized in a body of water and persist for long periods of time in contradiction of classical theory. The evidence was obtained by generating bubbles at the bottom of a water tank and then measuring the decay of ultrasonic attenuation as bubbles of various sizes rose to the surface. Comparison of experimental and classical decay curves disclosed persistence that appeared to be a function of the solid particle content of the water and indicated that bubbles may stabilize at sizes as large as 30 μ radius in water of high particulate content. In waters of low particulate content the decay of attenuation lasted over 100 hr.
Substantial persistent abnormal attenuation was detected in all fresh tap water measured, amounting to a minimum 44% over that of distilled water (at 5.125 Mc) and is believed to be caused by stabilized bubble nuclei somewhat less than 0.8 μ in size. An interesting discovery was that attenuation rose in an uncovered test basin but fell in a covered basin, indicating that microbubbles may enter water on dust particles.
A hypothesis presented to explain the persistence effect suggests that solid particles collect on the bubble surface, forming a compressed wall capable of supporting the excess pressure necessary to halt gas diffusion. Other hypotheses explore the mechanism by which dust particles may carry air globules below the water surface, and the dynamics of microbubble populations.

Application of the Theory of Signal Detectability to Amplitude Discrimination

Wilson P. Tanner, Jr.

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1233-1244 (1961); (12 pages) | Cited 2 times

Online Publication Date: 26 Jul 2005

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The fact that Weber's law appears to apply in the same way both to intensity discrimination for pure tones and to intensity discrimination for white noise poses a theoretical paradox: in the case of pure tones, the human observer becomes less efficient as the intensity of the tone is increased, while in the case of white noise he exhibits a constant efficiency independent of intensity.
An inventory of the various possible noise sources which may exist is made, and the way in which these may be expected to effect the detectability of a signal leads to the equation
math
, where η is the individual observer′s efficiency, NG is the noise introduced by the experimenter, NE is the uncontrolled noise present in the experimental situation, and k is a constant indicating that small amplitude variation in the oscillator constitutes a noise source proportional to the power of the lower of two signals to be discriminated.
Data for three observers over four noise levels is described by this equation sufficiently well to suggest that the hypothesis that Weber's law is merely a reflection of the oscillator noise (kV02) is plausible.
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Compressibility vs Ionic Size of the Cation in the Aqueous Solutions of Electrolytes

M. Suryanarayana

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1245-1245 (1961); (1 page)

Online Publication Date: 26 Jul 2005

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The compressibility of aqueous solutions of electrolytes with a common onion is found in the literature to decrease in some cases and increase in some others with the increase of the radius of the cation. It is suggested that the compressibility depends both on the hydration and the charge density of the ions, the effect on the compressibility of one being opposite to that of the other. The net trend of the compresibility depends on which factor is predominant.

Lagrangian One‐Dimensional Equations of Hydrodynamics for a Viscous, Thermally Conducting Fluid

David T. Blackstock

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1245-1246 (1961); (2 pages)

Online Publication Date: 26 Jul 2005

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The exact Lagrangian formulation for one dimensional, rectilinear motion of a viscous, thermally conducting fluid is derived from the corresponding Eulerian formulation. Applicable results are compared with the Lagrangian equations given by Fay (1931) and Lindsay (1960).

Internal Reflections and Low Frequency Cutoff In Nonuniform Transmission Structures

J. E. Holte and R. F. Lambert

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1246-1247 (1961); (2 pages)

Online Publication Date: 26 Jul 2005

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Stepped Waveguide Transformers and Filters

Leo Young

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1247-1247 (1961); (1 page)

Online Publication Date: 26 Jul 2005

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A review of recent developments in the synthesis of stepped quarter‐wave transformers and half‐wave filters is given. A recent paper by Holte and Lambert is discussed.

Acoustic Intensity Anamolies: Comments on a Paper by Pedersen

Kenneth R. Stewart

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1248-1248 (1961); (1 page)

Online Publication Date: 26 Jul 2005

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By use of a ray acoustical model of the ocean with linear sound speed gradients, the intensity is calculated when a ray is horizontal at a layer interface.

Remarks on Mr. Stewart's Comments on my Paper entitled “Acoustic Intensity Anomalies, etc.”

Melvin A. Pedersen

J. Acoust. Soc. Am. Volume 33, Issue 9, pp. 1248-1248 (1961); (1 page)

Online Publication Date: 26 Jul 2005

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