(1) The outer ear

Sound waves enter the outer ear and travel through the ear canal to the eardrum, causing it to vibrate.

(2) The middle ear

The vibrations travel to the eardrum, which is connected to three tiny bones in the middle ear called ossicles. The ossicles naturally amplify the sound before it enters the inner ear.

(3) The inner ear

This part of the ear contains a fluid-filled cochlea lined with thousands of tiny hair cells. As the fluid moves in waves along the cochlea, the hair cells bend and trigger impulses through the auditory nerve. The number of hair cells bending, and their location, determines the frequency and intensity of the sound.

(4) The auditory nerve

These impulses travel up the auditory nerve to the brain, where they are interpreted as meaningful sounds.

(1) The outer ear

Sound waves enter the outer ear and travel through the ear canal to the eardrum, causing it to vibrate.

(2) The middle ear

The vibrations travel to the eardrum, which is connected to three tiny bones in the middle ear called ossicles. The ossicles naturally amplify the sound before it enters the inner ear. Either the eardrum or the ossicles damages, the transmission of vibration can be affected, which may cause hearing loss.

(3) The inner ear

This part of the ear contains a fluid-filled cochlea lined with thousands of tiny hair cells, some of which are damaged or missing along the cochlea, causing the hearing loss. The frequency and severity of hearing loss depends on both the location and number of missing or damaged hair cells.

(4) The auditory nerve

These impulses travel up the auditory nerve to the brain. Here, the remaining functional hair cells can only transmit limited nerve impulses, or because of the lesions in the auditory nerve, it is difficult for the brain to receive complete acoustic information.

(1) The outer ear

Sound waves enter the outer ear and travel to the hearing aid, which amplifies sound to compensate for the hearing loss.

(2) The middle ear

Sound exiting the hearing aid travels to the eardrum, which is connected to three tiny bones called ossicles. The ossicles naturally amplify the sound before it enters the inner ear.

(3) The inner ear

This part of the ear contains a fluid-filled cochlea lined with thousands of tiny hair cells, some of which are damaged or missing, causing the hearing loss. At this stage, the sound has been amplified to compensate for the missing sounds and their location. As the fluid moves in waves along the cochlea, a greater number of intact hair cells are now able to bend and trigger impulses through the auditory nerve.

(4) The auditory nerve

Impulses from the increased number of hair cells travel up the auditory nerve to the brain and provide more information than would otherwise be available. This additional information makes it easier for someone with a hearing aid to interpret meaningful sounds.