ISSN:0001-4966    

DOI:10.1121/1.1916432

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1916434

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP

摘要:

Magnetic recording gives an ideal sound system for use in motion picture work. Equipment for making the record is light, simple, and inexpensive. The material can be edited by “cutting,” or by erasing and re‐recording. Sound can also be added after the pictures are complete. Conventional projectors are used with the magnetic system. Response comparable to optical recording is obtained with low distortion and noise. Recording heads, circuits, and mechanical drives for use with various systems are described.

ISSN:0001-4966    

DOI:10.1121/1.1916435

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP

摘要:

A stylus design is presented which combines the advantages of both large and small tip radii to secure satisfactory tracking on a wide variety of groove dimensions.

ISSN:0001-4966    

DOI:10.1121/1.1916439

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1916446

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP

摘要:

The fouling of transducers by marine organisms imposes a handicap on the use of underwater‐sound equipment, especially in low latitudes. Sensitivity and sound‐emitting power are reduced. In order properly to plan countermeasures, quantitative data on the effect that fouling organisms have on the reflection and absorption of sound have been accumulated by measuring a series of test panels which had been exposed to fouling in Florida waters. The test panels were measured periodically, at a frequency of 24 kc. The extent of absorption caused by fouling can reach a magnitude of 3 decibels per inch of thickness. Distortion of transducer patterns is another effect of the fouling. Antifouling methods are described. The acoustic attenuation of certain antifouling paints are found to be negligible.

ISSN:0001-4966    

DOI:10.1121/1.1916452

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1916471

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP

摘要:

The purpose of this paper is to present both theoretical and experimental findings in the use of convex wood splays for broadcast and motion picture studios. After a discussion of the term “diffusion,” there follow some calculations intended to circumscribe the term mathematically. An experiment is described in which pillars are used for added diffusion in a sound recording studio, and some criteria are cited for the use of such splays in studios.

ISSN:0001-4966    

DOI:10.1121/1.1916478

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1916489

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP

摘要:

The sound field of a point source near the boundary of two media cannot be obtained by an acoustic‐ray approach. In fact, such an approach which utilizes the reflection coefficient for plane waves leads to completely contradictory results at grazing incidence. A more rigorous solution is obtained, the procedure followed being exactly similar to that initiated by Sommerfeld to derive the electromagnetic field of a vertical dipole situated near a conducting plane. The results of such an analysis as applied to an acoustic point source are presented. As pointed out by Van Der Pol, the resultant solution may be regarded as that due to the point source and a diffuse image. The discussion of the solution is restricted to cases in which the sound source is at the boundary although it is given for all source heights. The solution shows that when the boundary medium has a high real specific acoustic impedance, non‐zero fields are obtained at all points along the boundary. For bounding media adequately described by simple porosity theory, the acoustic pressure at the boundary is inversely proportional to the square of the distance and the square of the frequency, at reasonably large distances and low frequencies. Also there appears to be decreased phase velocities along the boundary. Some calculations of the sound pressure as a function of height above Quietone show, among other things, the presence of a minimum occurring some distance above the boundary. At large distances from the source there are very large decreases in amplitude as the receiver height is increased in the region above this minimum.

ISSN:0001-4966    

DOI:10.1121/1.1916490

出版商:Acoustical Society of America    

年代:1947

数据来源: AIP