Useful terms about the ear and hearing

Here are some explanations for some of the terms that are used to describe the ear and hearing loss:

• Outer ear: This includes the visible part of the ear, the ear canal and eardrum
• Middle ear: The middle ear is an air filled space behind the eardrum containing small middle ear bones called the ossicles. The eustachian tube connects the middle ear to the throat
• Inner ear: The inner ear includes the cochlea which contains thousands of tiny hair-like cells which are sensitive to sound

How we hear sound

Sound is a vibration in the air which travels down the ear canal to the eardrum. The vibrations travel across the eardrum and along the bones of the middle ear to the cochlea. The vibrations initiate the hair-like cells in the cochlea to send electrical signals along the auditory (hearing) nerve to the brain where the sound can be heard.

What causes a hearing loss

Anything which reduces or prevents the sound signal before it reaches the brain causes some degree of hearing loss. Hearing losses can be mild (misses quiet sounds), moderate (difficulty with hearing speech especially in background noise), severe (cannot hear speech at all without hearing aids) or profound (little or no useable hearing).

Types of hearing losses can be described as:

• Conductive hearing loss: This type of loss may occur if there is a problem in the outer or middle ear, and may result in a temporary or permanent loss
• Sensorineural hearing loss: This type of loss may occur if the cochlea or hearing nerve is not working properly. Sensorineural hearing losses are generally permanent
• Mixed hearing loss: This is when a sensorineural and conductive hearing losses occur together