Hold a metal fork between your thumb and index finger. Hit it with a metal spoon. While the fork is still ringing, gently touch the handle to your teeth. What do you hear?
Many solid objects carry sound vibrations better than air does. Tiny vibrations in the fork can go through your teeth and the bones of your skull to your ears. In this way, you may even hear sounds from the fork that are too faint for your ears to pick up from the air.