Comment by Topfi
Accutrons and tuning fork watches are amazing. They have an incredibly unique sound/hum due to the tuning fork oscillating at 360 hz and the most smooth glide you'll ever see in a watch. Recommend a ESA 9162 or ESA 9164 over a pure Accutron for beginners though, a bit more resilient and far more affordable, though they don't have the exposed dial.
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.