I'll speculate "what is really happening" - Think of a voice like a musical instrument. This learned to be a Shazam for human voices instead of songs. And just

I'll speculate "what is really happening" - Think of a voice like a musical instrument. This learned to be a Shazam for human voices instead of songs. And just like you can figure out by ear a snippet of music was made on a Yamaha DX7, seems 15 seconds is enough to narrow it down to a reasonably small set of vocoders that can recreate the sample given.