MAGNETS TOSS VOICE BACK LIKE AN ECHO (Aug, 1933)
MAGNETS TOSS VOICE BACK LIKE AN ECHO
When a World’s Fair visitor speaks into the device shown above, an electric echo throws back his words after a pre-set interval up to several minutes. One set of magnets impresses the voice on a moving steel tape, and a second set picks it up. The effect sounds like an echo from a cliff, but undistorted and amplified. Delayed speech is useful in transatlantic radiotelephony, where a speaker’s reply is held up in transit to give relays time to close.