Normal sound waves are actually tiny vibrations in the air. The vibrations travel through the air to our eardrums. The eardrums, in turn, vibrate, decoding these sound waves into different types of vibrations that are received by the Cochlea, also known as the inner ear. The Cochlea is connected to our auditory nerve, which transmits the sounds to our brain.
Bone Conduction bypasses the eardrums. In bone conduction listening, the bone conduction devices (such as headphones) perform the role of your eardrums. These devices decode sound waves and convert them into vibrations that can be received directly by the Cochlea, so the eardrum is never involved. The “sound” reach the ears as vibrations through the bones (or skull) and skin.