I can sort of understand records mimicing the sound of instruments, but voices are so unique, how did we ever figure out the exact carving of a piece of vinyl that when you drag a needle across it, you’ll get the same sound as x or y person’s voice exactly?
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Someone said here a short while ago that sound is “wiggles in air”, and that’s a good place to start. All sound is movement of air; in the case of music and speech it is organised wiggles, but still wiggles nonetheless.
In the early days of recorded sound, no electronics were involved; singers and players sang or played in front of an acoustic horn which focused their sound wiggles on a cutting stylus, which vibrated in sympathy with the sound, and was used to cut a groove in a wax cylinder. No analysis was needed to force mimicry, for the vibrations/wiggles of the stylus simply moved in response to the air wiggles. The wiggles in the groove therefore automatically reflected the wiggles in the air.
To play it back, a similar stylus, without a cutting edge, was used to trace the groove previously cut, and the horn used to project the vibration of the stylus back into wiggles of air.
We moved on to the cutting stylus being used to cut grooves in laquer discs, and these were then used to form metalwork which could press a number of other discs, which had the same groove formation as the original cut of the laquer.
Again, no analysis is required, merely a way to connect the wiggles in the air with the physical process of cutting the groove, such that the cutting stylus moves in accord with the wiggles.
Even with today’s electronics, and storage of sound on tape, it still comes down to the same principle; connect the cutting stylus to the wiggles of the sound, and get it to move in sympathy with that. On playback, trace the groove and amplify the result through speakers to convert it back into wiggles of the air.
How do we recognise each voice? Each person has their own unique wiggle. All we need do is capture that wiggle, and play it back.
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