Vitaphone
From Loonipedia
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Vitaphone being used in the opening WB logo.
Vitaphone was a sound recording system used on Looney Tunes and Merrie Melodies shorts. From 1931 until 1939, the opening Warner Bros logo mentioned Vitaphone. From 1939 until the early 1960s, this was replaced with "WARNER BROS." Also, on the ending titles of many of the early 1960s cartoons, Vitaphone was mentioned.
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The rarely used early 1936 opening, only appeared in I Wanna Play House.