ISSN:0001-4966    

DOI:10.1121/1.1915704

出版商:Acoustical Society of America    

年代:1934

数据来源: AIP

摘要:

Rectification in the ear is of some importance in the study of propeller noise. Data on this phenomenon have been obtained by using modulated signals. Twenty out of twenty‐one observers were able to hear the modulating frequency as a result of rectification. Quantitative estimates of the magnitude of this subjective tone have been obtained. Measurements have been made of the increase in loudness level due to rectification. Results indicate that rectification may be a property of the basilar membrane rather than of the ear drum or the ossicles of the middle ear, as previously supposed.

ISSN:0001-4966    

DOI:10.1121/1.1915705

出版商:Acoustical Society of America    

年代:1934

数据来源: AIP

摘要:

The loudness and tone quality of a piano note are determined by the motion of the hammer at the time of its impact with the string—theoretically, by its velocity, acceleration and higher time derivatives. Practically, due to the great rigidity of the hammer shank, the influence of the acceleration and higher derivatives is negligible. This study presents exact quantitative confirmation of the findings of other investigators that the loudness and tone of a piano note are uniquely determined by the velocity of the hammer at the time of impact with the string.

ISSN:0001-4966    

DOI:10.1121/1.1915706

出版商:Acoustical Society of America    

年代:1934

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915707

出版商:Acoustical Society of America    

年代:1934

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915708

出版商:Acoustical Society of America    

年代:1934

数据来源: AIP

摘要:

A series of tuned reeds are mounted so that they may be electromagnetically driven. Each reed carries a small concave mirror with which light from an illuminated slit is brought to a focus on a screen. These slit images are lined up in the order of the reed frequencies. When a current having a complex wave, such as the speech current from a microphone, is passed through the electromagnet, the reeds and in consequence the slit images on the screen will oscillate. The driving system and the reeds are so designed that the amplitude of oscillation of each image is proportional to the strength of the corresponding harmonic component in the driving current. Therefore, by observing or photographing the slit image amplitudes, the frequencies and the relative energy content of the components of a complex current may be determined. A spectrometer of this type covering a small frequency range (50 to 3109 cycles) was built for demonstration purposes. The range of such an instrument can be extended to higher and lower frequencies.

ISSN:0001-4966    

DOI:10.1121/1.1915709

出版商:Acoustical Society of America    

年代:1934

数据来源: AIP

摘要:

An alternate derivation of the Bateman formula for Doppler's principle is described. A method is given for the evaluation of the direction cosines which appear in this formula, so that in the special case of constant velocities of sound, and of the mediumν′ν = u[a2−(v2+w2)]12+a2−v2−w2−[a2−(v2+w2)]12U1+vV1+wW1u[a2−(v2+w2)]12+a2−v2−w2−[a2−(v2+w2)]12U0+vV0+wW0whereu, v, ware component velocities of the medium,ais the velocity of sound,U0,V0,W0the component velocities of the source, andU1,V1,W1those of the observer. Thex‐axis here connects source and observer, and ν and ν′ are, respectively, the original and observed frequencies. The case of a stratified medium is also considered.

ISSN:0001-4966    

DOI:10.1121/1.1915710

出版商:Acoustical Society of America    

年代:1934

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915711

出版商:Acoustical Society of America    

年代:1934

数据来源: AIP