Recent research reveals some fun facts about aural-tactile synesthesia:
Both hearing and touch, the scientists pointed out, rely on nerves set atwitter by vibration. A cell phone set to vibrate can be sensed by the skin of the hand, and the phone’s ring tone generates sound waves — vibrations of air — that move the eardrum…
A vibration that has a higher or lower frequency than a sound… tends to skew pitch perception up or down. Sounds can also bias whether a vibration is perceived.
The ability of skin and ears to confuse each other also extends to volume… A car radio may sound louder to a driver than his passengers because of the shaking of the steering wheel. “As you make a vibration more intense, what people hear seems louder,” says Yau. Sound, on the other hand, doesn’t seem to change how intense vibrations feel.