Bone Conduction Hearing Devices

How we hear

The ear is made up of three sections:

The outer ear – the external ear and ear canal

The middle ear – the eardrum and ossicles (middle ear bones)

The inner ear – the organ of hearing, called the cochlear, and the auditory nerve

Generally, we hear via air-conduction. This means sound waves travel through the air, down the external auditory ear canal to the eardrum. The eardrum vibrates, which in turn causes the middle ear ossicles (the smallest bones in the body) to move. The ossicles pass the vibrations through to the fluid in the inner ear (cochlea), where tiny hair cell receptors turn the vibrations into electrical signals to be recognised as sound by the brain.

Video courtesy of Med-El

We can also hear through the bone. If a vibrating sound source is placed on the bone, these vibrations can also cause the fluid in the inner ear to vibrate, stimulating the hair cell receptors and creating an electrical signal.

Listening to a bone-conduction source by-passes the ear canal, ear-drum, and the middle ear, where there may be problems such as infection or a perforated eardrum, preventing the air-conduction sounds from passing freely.

This is the situation where a bone-conduction hearing device (BCHD) may be the most useful type of hearing aid to use.