1940s

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1940

First use of stereophonic sound in a film: Walt Disney's Fantasia

1942

Helmut Krüger makes the first recordings on stereophonic magnetic tape for German radio in Berlin.

1947

John Bardeen, William Shockley and Walter Houser Brattain, researchers at the Bell Telephone Company, invent the germanium transistor.

1948

Columbia Records patents Long Play records, which spin at a speed of 33? rpm.

1949

The 45 rpm or single record appears, used by record companies to launch their new releases.