摘要:

Two highlights of musical acoustics of the past twenty‐five years are the advent of practical electrical musical instruments and research on deviations from the regular in music. Included in the latter are studies of the vibrato, transient modifications of tone quality, departures of intonation from rigid scales. The “steady‐state” concepts of the past now need refurbishing in the light of “deviation” evidence. An analysis of papers directly related to music and published in the first twenty‐five volumes of theJournal of the Acoustical Society of Americareveals a steadily increasing interest in musical acoustics until World War II. In common with other subjects the publication rate dropped sharply during the war. Publication in acoustics as a whole increased rapidly after the war, but interest in musical acoustics (at least as evidenced by papers in theJournal) did not revive. Patents on musical devices, however, now constitute a significantly larger percentage of the annual output of the U.S. Patent Office than was the case in 1941. Technology is outstripping research in musical acoustics; interest in research must be revived immediately for the benefit of those who will listen to music in the next twenty‐five years.

ISSN:0001-4966    

DOI:10.1121/1.1907459

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP

摘要:

Oscillograph records of the initiation of sound in organ pipes and orchestral wind instruments show large variations from one instrument to another. The causes of these variations and their artistic effects are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1907460

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP

摘要:

A pulse method is described employing a “sing around circuit” wherein each new pulse is triggered by the preceding pulse after it has traversed the acoustic sample. The resulting pulse repetition rate is measured with an electronic stop watch, thus giving a measure of the combined acoustic and electronic delay times. This in turn, upon the elimination of the electronic delay time, gives the velocity of sound in the sample. Velocity data are presented and sources of error discussed.

ISSN:0001-4966    

DOI:10.1121/1.1907461

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP

摘要:

The amplitude absorption coefficient α for continuous ultrasonic waves in aqueous solutions of copper acetate, sodium acetate, and potassium acetate has been measured over a range of frequency from 7 to 45 mc, at temperatures between 5° and 50°C, and at concentrations up to 0.5M. The experimental values for copper acetate solutions confirm the existence of a relaxation frequency at about 18 mc (at the higher concentrations). The results for sodium and potassium acetate solutions show an absorption coefficient below that of pure water at the higher frequencies. They also indicate the existence of relaxation frequencies below 10 mc.

ISSN:0001-4966    

DOI:10.1121/1.1907462

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP

摘要:

An analytical treatment for the calculation of intensities of diffraction orders in a general case of superposed sound waves of frequencies in the ratio 1 :nand having any phase difference Δ is given proceeding from Raman and Nath's simplified theory for normal incidence. Because of the integral harmonic relationship between the frequencies of the sound waves superposed, a particular order may contain a number of combination lines in addition to the orders due to the individual sound waves. As such, Fues theory, which gives a single expression for the intensity of a combination line, cannot be applied to this case.Expressions are obtained for the intensities of the diffraction orders in the two specific cases of even and odd values ofn. In the case diffraction by two sound waves of frequencies in the ratio1:2k+1expressions for the intensities of the orders suggest symmetry in diffraction for all values of Δ. But, when the superposed frequencies are in the ratio 1:2k, the expressions suggest asymmetry in diffraction for all values of λΔ, except π/2. When Δ = π/2, the diffraction is, however, symmetric.Using the expressions, the intensities of the diffraction orders obtained by two sound waves of frequencies in the ratio 1:3 superposed in three different phases 0, π/2, and π are calculated for the values ofv1 = 1andv3 = 1, 2, and 3.

ISSN:0001-4966    

DOI:10.1121/1.1907463

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP

摘要:

On the basis of a simplified model an explanation for the high‐frequency limit of ultrasonic cavitation is suggested and compared with published experimental data.

ISSN:0001-4966    

DOI:10.1121/1.1907464

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP

摘要:

A two crystal interferometer for rapid measurement of sound velocity in liquids and soft animal tissues is described. Velocities can be determined to within three parts per thousand with a path length of a few millimeters. The frequencies used are 1, 2, 4, 12, and 36 mc. Temperature is controlled to 0.1°C. A phase comparison method is used for wavelength incorporating dual heterodyne reduction to audio‐frequency with presentation as a Lissajous figure on an oscilloscope. Results are given for a few mammalian tissues showing the precision and reproducibility of measurements.

ISSN:0001-4966    

DOI:10.1121/1.1907465

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP

摘要:

The hypothesis discussed that the cavitation nuclei consist in gas bubbles. Due to surface tension, small bubbles would dissolve in a very short time. If the bubbles are larger than5×10−3 cm, or if the liquid is supersaturated, they may last longer or even be stable, but then no cavitation threshold exists.The hypothesis expressed that the nuclei are very small bubbles, stabilized by an organic skin, which mechanically prevents loss of gas by diffusion. The cavitation occurs when the skin breaks and the threshold is determined by the breaking strength of the film and the size of the bubble.

ISSN:0001-4966    

DOI:10.1121/1.1907466

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP

摘要:

The effect of electrical conductivity and viscosity of the piezoelectric medium propagating plane waves has been studied. The solution of Maxwell's field equations and Newton's law of force in the general medium gives the modified elastic, piezoelectric, etc., constants necessary for determining the phase velocities of the plane waves. These modified constants are found to be complex and frequency dependent. Thus the propagation constants for the waves are complex and frequency dependent.A particular example, propagation in the 1‐direction of ammonium dihydrogen phosphate, is considered.

ISSN:0001-4966    

DOI:10.1121/1.1907467

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP

摘要:

The coefficients of absorption of high intensity ultrasonic waves in liquids (carbon tetrachloride and water) have been measured as a function of intensity. The absorption coefficient increases by a factor of 5 for water and 2 for carbon tetrachloride for intensities of about5 watts/cm2. The increase is attributed to wave form distortion of a wave of finite amplitude. A theory is developed in which the medium is treated as the acoustical analog of a transmission line with nonlinear elements. The theory enables one to follow the details of the change of an initially sinusoidal wave of finite amplitude, in a dissipative medium, in to a “comparatively” stable distorted wave form that eventually returns to an infinitesimal sinusoidal wave. Quantitative agreement of theory is obtained with experiment for the distance needed for comparative stabilization, the growth of harmonic content in the distorted wave, and the details of the absorption process.

ISSN:0001-4966    

DOI:10.1121/1.1907468

出版商:Acoustical Society of America    

年代:1954

数据来源: AIP