The audio bumper in 1931 was the three chimes of the notes G, E and C that we still hear today. They took those from a local Atlanta, Georgia radio station that had used the chimes as a signal to their staff. Also, "the weird thing" is just an early microphone. Microphones had only come into wider use about 3 years before in 1923, so they didn't look the way they do now.
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