[briansm]

I believe this is why all modern digital watches use a 32768.0Hz crystal resonator, it's a power-of-2 frequency above the 20Khz top end of the range of human audio perception, to avoid the whole 'tinnitus on your wrist' thing.

[namibj]

Also a tuning fork cut for a lower power-of-two would be a bit bulky for a compact wrist watch.