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About Hearing

The Outer Ear

The outer ear comprises of the pinna at the side of the head, a canal through which sounds travel and at the end of the canal, the eardrum. The ear canal is curved and irregularly shaped. It is about 2.5 cm in length and about 8 mm in diameter. The curvature of the ear canal prevents the gathering of water and other foreign materials in the canal. The ear canal also keeps the eardrum at a constant temperature and humidity. The outer portion of the ear canal is relatively soft, while the inner part is hard and bony. The wall of the ear canal contains glands, which secrete earwax (cerumen). The outer ear serves to localize, collect, lead and enhance sounds. It also functions as a protective mechanism for the middle ear.

The Middle Ear

The middle ear is the air-filled space located behind the eardrum. In the middle ear cavity there are three small bones called the ossicles; these are the hammer, the anvil and the stirrup. When sound makes the eardrum vibrate, the chain of bones is set into vibrations, and the stirrup induces a wave movement in the liquid in the inner ear.

The Inner Ear

The inner ear is filled with fluids and many microscopic components, all of which behave like a microphone and send the hair cells into motion. Different hair cells correspond to different sounds with the low frequency sounds placed at the top of the cochlea and the high frequency sounds at the bottom. The vibration will thereby convert sound waves into a message that travels to the brain via the auditory nerve.

Types of Hearing Loss

There are different ways hearing loss can affect people.

Conductive Hearing Loss

Conductive hearing loss occurs when sound waves are blocked in the outer or middle ear and can’t reach the inner ear, where hearing is still normal. People affected by conductive hearing loss often experience an overall reduction in the volume of sounds and find it difficult to hear faint sounds. Most conductive losses are not permanent and can be treated medically or surgically. We liaise closely with our ENT consultant colleagues for referral if this is needed.

Congenital Hearing Loss

Congenital Hearing Loss is when a patient is born with a hearing loss. This can be due to genetic causes or from such infections passed on from the mother when the baby is still in the womb, such as German Measles.

Normal Ear Drum
Cochlea

Sensorineural Hearing Loss

Sensorineural hearing loss, also known as nerve deafness, accounts for 90% of adult hearing problems. Sensorineural hearing loss occurs when the hair cells in the cochlea become damaged and sound cannot reach the brain (where sound is processed).

Once the hair cells have been damaged, they cannot be repaired, making sensorineural hearing loss permanent. Sensorineural hearing loss usually results in the overall reduction in the loudness perception of sounds and can also cause sounds to become distorted. There is often a loss of speech perception, particularly in background noise.

Hearing aids can help in most cases. High frequency hearing loss is experienced by one in two people over the age of 50.

This type of hearing loss is a natural part of the aging process, but it can also be caused by over exposure to loud noise or loud music. People with high frequency loss have difficulty hearing softer, high-pitched sounds (like ‘s’, ‘t’ and ‘f’), but no difficulty hearing the deeper vowel sounds. In quiet listening situations they can follow a conversation, but when it gets noisy, they need amplification in order to hear clearly.

In order to determine the degree and nature of any patients hearing loss we perform a full Audiological examination.