The Process of Normal Hearing
- Normal hearing occurs when sound enters the external ear, travels through the ear canal and reaches the eardrum.
- The eardrum is the start of the middle ear. The eardrum vibrates in response to the sound and this causes vibration in the chain of the three bones in the middle ear.
- The vibration is transferred to the inner ear or cochlear. The cochlear consists of nerve fibres (hair cells) that receive sound. Different hair cells are responsible for receiving different pitches of sound.
- The signal is transferred via the auditory nerve to a nucleus in the brainstem, which, if it receives a signal from both ears, can:
- know the direction of sound
- boost speech above background noise
- help with perceptions of balance
- Then, it is transferred to the auditory cortex in the thinking brain, where the signal’s message is understood.