It’s not a pressure wave. It’s an entirely different mechanism.

The fork tines oscillate back and forth as the metal bends at the base of the tines. There is no propagating wave through the metal. It’s really more like the motion of a spring.

Not all vibration crates sound and vibration is never sound in and of itself.

All atoms are vibrating all the time. But they are so small and there are so many of them vibrating out of sync with one another that a pressure wave never develops in any given direction.

Noise canceling headphones cancel the noise by oscillating out of phase with a sound wave so that the sound wave is canceled. So that’s a case where vibration actually eliminates sound.

Vibration is not sound.