TALKING MOTION PICTURES.

Press, Volume LIX, Issue 17707, 8 March 1923, Page 12

TALKING MOTION PICTURES.

FEAT OF NEW DEVICE •An ingenious apparatus km recording sounds upon a pihotographio film so that the sound may afterwards be reproduced in ordinary telephones, loud speakers, etc., has recently been developed in the laboratories of tho General Eleotrio Company, U.S.A. The possibilities of this device are great. It makes possible the talking motion picture, for on a film of ordinary width both the voice and the photographio record of his action may be recorded, with voioe and action perfectly synchronised through being of the same fiLm.

It also means a boon to radio broadcasting, for from . a great central station, the best artists might make photographio records which cou.d later be sent out to smaller stations and be reproduced with tha same clearness as the origiriaji production. The record is made by causing sound waves to produce vibrations on on, exceedingly minute and delicate mirror. A beam of jight reflected' by this mirror strikes a photographic film which is kept in coiitinual motion. The film when developed shows a band of white with delicate indentations wliich corresponds to the violations of the sound which is being reproduced. On account of the exceedingly small size of the mirror, its low inertia, eto., it is possible by this means to produce a sound record which includes the very delicate overtones which give quality to speech and musical sounds which have hitherto eluded other methods of sound recording. The reproduction of. the sound from the film is accomplished by moving the film in front of a delicate elecfrical device which produces an electromotive force varying with the amount of light which falls', upon it. In the. past attempts have been made to produce these results by means of selenium cells, but these cells, although they respond to varying intensity of light, do not respona with sufficient promptness to bring good results; there is a sluggishness in the response which seniously interferes with the quality of sound which is produced. By an ingenious combination of vacuum tubes, a device has been perfected which responds to light variations with a speed so great that it may be compared with that of light itself. Hence, when ' the new type of film is passed before this device, an electric current is produced- which corresponds very accurately to the o-.tginal sound waves. This current may be used to actuate a telephone or loud speaker. The new device was tested recently in the operation of the radio broadcasting station of the General Electric Company at Schenectady, N.Y. The well-known voice of the announcer was photographed and sent out by this station with such accn:ncy that those receiving the message were unable to distinguish the result from the customary announcing.