摘要:

Previous to the development of amplifiers most of the instruments used in acoustical research depended for their operation upon purely mechanical principles. This paper includes a brief survey of such of these instruments as are still of interest in connection with the investigation of technical or research problems in acoustics, but it deals primarily with the more recent electrical devices used in the study of air‐borne sound waves. The limitations and fields of application of various electrical instruments, including microphones, particularly adapted to definite types of acoustic measurements, are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1915750

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP

摘要:

This study of the velocity of high frequency sound in small tubes covers the range of frequency from about 10 to 80 kilocycles per second, and in diameter from 1/2″ to 3/16″. The method of G. W. Pierce, using magnetostriction oscillators, has been followed, providing high accuracy of measurement. Careful precautions in the construction were taken to eliminate the variations due to humidity, impurity, and to spurious reflections. The results tend to support definitely the Helmholtz‐Kirchhoff reduction law, but provide a smaller observed value of the constant for pure air compared to the theoretical value. The value of free space velocity derived from these experiments checks that independently obtained by Grabau, using a similar method in air, to within 1 part in 4000. Hence the present tube method may be applied to delicate measurements of sound dispersion in pure gases, and their mixtures.

ISSN:0001-4966    

DOI:10.1121/1.1915751

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915752

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915753

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP

摘要:

It is the purpose of this paper to present further evidence that supersonic waves in air have a velocity which depends on their intensity and that this velocity approaches the limiting value(γP/ρ)12at comparatively low intensities.

ISSN:0001-4966    

DOI:10.1121/1.1915754

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP

摘要:

The lack of agreement among previous measurements of differential intensity sensitivity indicates that the values obtained depend to a large extent on the experimental conditions. The relative importance of various factors is indicated, and a procedure is suggested which was designed to give the smallest possible values of differential intensity sensitivity. Intensive measurements made by this method upon a single subject, using a pure tone of 1000 cycles gave values consistently smaller than any previously reported. There is no sharp division between intensity changes which can be perceived and those which cannot. The response of the subject is essentially variable and can only be described by statistical methods.

ISSN:0001-4966    

DOI:10.1121/1.1915755

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915756

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915757

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP

摘要:

Following Stewart, a discussion of the application of the principle of uncertainty (ΔνΔl≈ 1) to sound phenomena is given. Various sound phenomena are thereby explained and certain related experiments with frequency vibrato are reported. The phenomena explained are: The chromatic glissando imitation of a portamento, analysis of a formant into a Fourier series, the relation between vibrato wideness and pitch range and the pleasing effect of a frequency vibrato.

ISSN:0001-4966    

DOI:10.1121/1.1915758

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP

摘要:

An experimental investigation of Kundt's tube phenomena has been performed with the primary purpose of investigating the actual motions and appearances of the striations under different conditions. No attempt was made to formulate rigorous theories explaining the figures. Very clear photographs of the particles in a striation were made by causing the striation to move out to the end of the tube and remain stationary long enough to be photographed. Photographs were also taken through the eyepiece of a microscope. From these it was evident that the particles in a striation did not, in general, touch each other. Striations on either side of a long metal rod on the bottom of the tube usually showed different spacings and occurred in different numbers on either side. This could not be caused by overtones since it is unlikely that more overtones could exist on one side than on the other. An electrostatic charge in motion near the tube prevented the figures from forming. A stationary charge in no way prevented their formation. Figures destroyed by the motion of a charge would slowly build up again when the charge was brought to rest, even with the charge present.

ISSN:0001-4966    

DOI:10.1121/1.1915759

出版商:Acoustical Society of America    

年代:1935

数据来源: AIP