What is sound?
When you clap your hands, strike something with a hammer or hum a tune, the surrounding air vibrates in the form of waves, similar to waves on water. These waves strike the eardrum, which functions much like an actual drum and transmits the vibrations through a chain of ossicles to a fluid contained in a special snail-shaped tube, the cochlea. The walls of this tube are covered with tiny hairs. If the sound is low, it will not travel far. If the sound is high, it will travel farther in the cochlea. The sound you hear varies depending on which hairs vibrate.