File:Bell telephone magazine (1922) (14755692302).jpg

Identifier: bellvol25telephonemag00amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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se the new method. Recording Sound on Film During the developments leading upto the orthophonic phonograph, otherWestern engineers steadily advancedthe art of recording sound on film. Donald MacKenzies studies ofphotographic emulsions and the treat-ment of film had commenced in 1922. In 1923, equipment was devised forsynchronizing the film recorder andmotion picture camera by means of anelectrically operated gearing. In that year Wente and MacKenziemade broader studies of emulsions,the problem of printing positives fromnegatives, amplifiers, the character-istics of light-sensitive devices, acous-tics of recording studios, and micro-phone placement for sound pick-up. In May 1923, Maxfields group wasmaking synchronized talking pictureswith local talent speaking, singing, andplaying musical instruments. In Octo-ber 1923, a synchronized picture andsound-on-film recording was made andexhibited to members of the labora-tory. In November 1923, a one-act 1946 Twenty Years of Talking Movies 95
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Cutting a disc in ig26. The apparatus at the left is engraving sound vibrations on awax disc, duplicates from which will be played in synchronism with a film sketch was similarly photographedand recorded. By March 1924, MacKenzie con-cluded that better results would be ob-tained in recording sound on film byusing a positive emulsion instead ofthe high-speed negative emulsion em-ployed up to that time. The motionpicture industry was then using a rela-tively coarse-grained negative emul-sion of great light sensitivity and con-sequently of great speed. The development of Wentes lightvalve, with its ability to modulate alight of relatively high intensity, en-abled use of a much finer grainedemulsion and lower speed, thus obtain-ing a sound record of improved qualityand frequency range with much lessbackground noise. The recording onpositive emulsion was later to become standard practice in the motion pictureindustry. It will be seen that co-incident withmastery of the art of sound on disc

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