摘要:

In a previous article, the author described an experimental arrangement suitable for generating small‐scale near‐boundary acoustic streaming, i.e., “microstreaming,” in a precise and controllable manner. Such microstreaming is of particular interest insofar as it can have considerable influence on processes taking place at a solid‐liquid interface. In the present paper, results of a comprehensive study of the microstreaming flow field associated with the aforementioned experimental system are discussed in some detail. Photographs are shown of the various flow configurations, and data are presented on streaming speeds as a function of significant experimental parameters. Theoretical expressions are developed along lines of conventional acoustic streaming theory to describe various features of the flow. The correlation between theory and experimental results is found to be good when certain criteria, described herein, are fulfilled.

ISSN:0001-4966    

DOI:10.1121/1.1907915

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The mean translation and rotation of a body having elastic constants and a density that differ only slightly from those of an otherwise homogeneous medium in which it is imbedded and having dimensions that are small compared with the wavelength are calculated for an arbitrary incident wave field. The problem is reduced to the evaluation of two integrals in potential theory, and explicit evaluations of these integrals are given for an ellipsoid. The results are applied to the motion of a sphere and a prolate spheroid under the influence of planePandSwaves.

ISSN:0001-4966    

DOI:10.1121/1.1907917

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The effect of diffraction in increasing the velocity of propagation over the plane wave value is determined experimentally by phase comparison of reflected longitudinal waves in fused silica blocks. It is shown that the parameters of transducer diameter, path length traveled, and frequency can usually be adjusted to keep the fractional excess velocity under 0.02% for measurements in the 20–100‐Mc range. This consideration is of particular importance in connection with precision measurement of elastic moduli.

ISSN:0001-4966    

DOI:10.1121/1.1907919

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The plane‐strain vibration frequencies of an infinitely long hollow cylinder are calculated exactly with the aid of a high‐speed electronic computer for a range of wall thicknesses and azimuthal node numbers and for a variety of boundary conditions. These latter cover the cases: outer radial surface free, supported, or clamped; inner surface free, supported, or matched to a gas filling the inner cavity. In the last case, we calculate the attenuation of sound in the cylinder wall, in addition to the eigenfrequencies. Our computations of mode frequencies disclose that: (i) the shear‐compressional wave coupling in the solid is very weak (except for low frequency); (ii) for the gas‐filled cylinder, the modes are very close either to the gas quasi‐modes (gas in a rigid‐walled cylinder), or to the solid quasi‐modes (shell with free inner surface), depending on the geometry.

ISSN:0001-4966    

DOI:10.1121/1.1907921

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

This paper presents an approximate theory (with sample calculations) for the thickness eigenmodes of an infinitely long hollow cylinder of arbitrary wall thickness, and subject to a variety of boundary conditions. Beginning with the earlier observation that the coupling between shear and compression waves in the solid wall is weak, a perturbation theory is deduced by which approximate eigenfrequencies can easily be computed by hand, with accuracy better than several percent provided the number of radial nodes is more than a few. The perturbation method can also be used to compute the attenuation of sound in the cylinder wall.

ISSN:0001-4966    

DOI:10.1121/1.1907923

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The radiation resistance of a nickel magnetostrictive‐stack transducer in the presence of an identical in‐phase transducer at an air‐water surface was obtained. The transducers are resonant at 20 kc and their radiating surfaces are squares whose sides are 0.38 of the wavelength in water. Curves were obtained for the radiation resistance vs separation distance for electrical driving forces of the interacting transducer which were 1.0, 2.0, and 3.9 times the electrical driving force of the reference transducer. It was found that for a given driving force ratio, the radiation resistance with interaction oscillated about the value for the radiation resistance of the transducer with no interaction and that these oscillations decreased in amplitude as the separation distance was increased. Near 2λ, the interaction effect became negligible. Furthermore, it was found that the interaction increased with increasing electrical driving force of the interacting transducer. Qualitative agreement is found with treatments of the interaction radiation resistance of other physical situations, but an adequate analytical study of this case is needed.

ISSN:0001-4966    

DOI:10.1121/1.1907925

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

The velocity of sound is determined in distilled water over the temperature range from 22 to 25°C. The method used consists of measuring the transit time of two sound paths of different lengths traveling between the crystal faces of two barium‐titanate transducers. With an accurate measure of the length, the velocity is determined from the quotient of ΔI/Δt. It is believed that the accuracy of the measurements is within ±1 ft/sec.

ISSN:0001-4966    

DOI:10.1121/1.1907927

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

Apparently the pitch difference limen (DL) for a single high‐frequency sinusoid can be smaller in the presence of a nearby constant frequency component than in isolation. It is demonstrated that this effect arises from the time‐envelope properties of the two‐frequency complex. This result is consonant with those of Flanagan and Saslow who found that the pitch DL of a periodic vowel sound is smaller than the DL of a sinusoid at the fundamental frequency.

ISSN:0001-4966    

DOI:10.1121/1.1907930

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

Conventional thermal microphones record the temperature increase generated by the absorption of acoustical energy. The microphone described in this paper measures the periodic change of the temperature that is generated by an amplitude‐modulated sound wave. This microphone is small, omnidirectional, free of drift, and extremely sensitive. Temperature variations in the order of 3×105C have been recorded by means of a narrow‐band amplifier tuned to the modulation frequency. The temperature distribution in a thermocouple enclosed in a sound‐absorbing material, and the optimum modulation frequency are calculated. A relaxation function is introduced to help interpret the results physically. Also, the electronic input circuit is discussed in detail.

ISSN:0001-4966    

DOI:10.1121/1.1907932

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP

摘要:

From the study of subharmonic series found in the violin and related instruments, it is evident that the quality and loudness of the instruments depend on the pitch and variety of the subharmonic series, and on the characteristics of the wood and the fashioning of the top and back plates. Details are given on the nature of subharmonic series and their presence as observed in several methods of testing. The single air tone, heretofore reported, is shown by more detailed tests to consist frequently of two or more closely related peaks. Observations made in a series of experiments carried on during the construction of 35 violins, violas, and cellos indicate a method of controlling tone quality and volume of the completed instrument by means of the tap tones and the acoustic properties of the free plates. Experimental equipment which makes these findings possible is described in detail. With this concept of subharmonic series and the techniques described, a large field for experimental evaluation of string instruments may well be opened up.

ISSN:0001-4966    

DOI:10.1121/1.1907934

出版商:Acoustical Society of America    

年代:1960

数据来源: AIP