摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.1908937

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.1908939

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.1908941

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.1908943

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

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 anefficientprocedure 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.

ISSN:0001-4966    

DOI:10.1121/1.1908945

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.1908947

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

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 distancesX⩽L, whereLis the discontinuity distance for the dissipationless case.

ISSN:0001-4966    

DOI:10.1121/1.1908949

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.1908952

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.1908954

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.1908956

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP