Oh, and it's not a "measure" of what's different between two voices (be they human or instrumental) producing a sound with a fundamental frequency at 440 Hz. They are two completely different waveforms. It's only the slowest part of the waveform that's cycling at 440 times a second. That's what gives any instrument its unique timbre.

But it is possible to digitally capture and accurately reproduce any of those sounds that exist below the Nyquist of the sampling system.
Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs