Music Reproduction Research Articles

The Columbia Long-Playing Microgroove Recording System

The Columbia LP (long-playing) microgroove recording system was developed to fill the need for music reproduction which would avoid interruptions not intended by the composer, and which would be of excellent quality at a reasonable cost. This allimportant factor of cost and the public's familiarity with the handling of phonograph records made it desirable to solve the task on the basis of records, rather than tape or wire. Standard 78-rpm records were originally designed to generate sound mechanically by direct transfer of energy from the groove of the record to the vibrating diaphragm. Because the entire acoustical energy had to be extracted from the grooves, these had to be quite rugged, and remained so up until now. The new Columbia recording system was an inevitable outcome of the use of electrical amplification between the groove and the loudspeaker. Today, practically no mechanical energy needs to be extracted from the groove, and thus, for the first time, it has been possible to develop much finer grooves, permitting longer playing time and distortion-free reproduction.

The Problem of Frequency Range in Speech and Music Reproduction

The specification of a frequency range for a speech or music reproducing system is a complicated matter, with immediate implications as to quality, efficiency, cost, and bulk. The boundaries of the spectra of speech and music are well established but the cost of reproducing these extreme ranges in a near-ideal manner is prohibitive for all ordinary applications. Studies of masking by noise and of hearing ability in the population indicate that statistically there is no real loss in restricting the band width to the order of half that of the original spectrum. Furthermore, it is the opinion of many experienced observers that something less than the complete spectrum yields optimum listening enjoyment and satisfaction. Further restriction of the frequency range entails loss of quality for essentially distortion-free sources with low noise content. The situation is examined for both speech and music with the aid of frequency diagrams for the audio frequency range which show the relationships between cut-off frequencies, band widths and the various criteria of quality and intelligibility. A rational system for departing from the complete frequency range can be developed in the form of a preferred series of reproduction bands based on the liminal intervals of Gannett and Kearney and aural balance relationships. This provides a practical approach to a system of bands with definite but just-perceptible quality differences between them, which is a most useful concept and one which would greatly aid in the engineering of sound systems. In the case of amplified speech communication, where the emphasis shifts from quality to effectiveness from a communications viewpoint, articulation, power economy, directivity and similar considerations, different bands are necessary and possible frequency ranges are discussed.

Music as a Vocation

T WO OF THE MANY questions that concern persons interested in the vocational aspects of the music profession are: (1) Is the listener audience increasing? (2) What are the opportunities for placement ? Let us remind ourselves that it has been only in recent generations, particularly in America, that music has been regarded as a profession-a profession considered to be important remuneratively. Since, up through the twenties, music came to be a profession of extensive ramifications in this country, its recent seeming decline in vocational value has been to many music people a disappointment and hurt. Since 1926 there have been technological changes in the music profession because of the increase of theaters using mechanical music reproduction, and because of the increase of the radio field. Most significant is the fact that the drop-off in the number of theater musicians has been considerably greater than the increase in the number of radio musicians. In 1928-29 there were 19,780 active theater musicians in the American Federation of

Recording Music for Motion Pictures

The performance standards required for musical reproduction were established in the research laboratories of the General Electric Company early in the period of development of Photophone equipment. Experience has proved the necessity of the refinements found desirable in the research laboratories. — In this paper several developments are referred to that have reduced distortion. It is pointed out that perfect equipment does not necessarily result in satisfactory musical reproduction. Consideration must be given to the acoustical properties of scoring stages.

On the Realistic Reproduction of Sound with Particular Reference to Sound Motion Pictures<!--<xref ref-type="other" rid="fn1-10.5594_J07426">*</xref>-->

The criteria for realistic reproduction of sound are discussed, showing how directional sound-collecting and dispersing systems may be employed to give results comparable with those of an ideal binaural system of reproduction. The use of a directional sound-collecting system, together with a directional sound-dispersing system, establishes: a “center of gravity” of the action; an illusion of depth or perspective; an acoustical or reverberation characteristic compatible with the picture; a large ratio of direct to reflected sound in the theater, emphasizing the acoustical properties of the theater; in musical reproduction, a correct balance and reverberation characteristic by the use of the two parameters.