Hearing loss happens when one or more parts of the ear aren’t working effectively. The ear is the first part of the hearing system. The outside part of the ear catches sound waves and directs them down the ear canal. The waves then cause the eardrum to vibrate.
These vibrations are passed across the middle ear by three tiny bones. These bones increase the strength of the vibrations before they pass through the oval window into what is known as the cochlea.
The cochlea looks like a snail’s shell. It’s filled with fluid and contains thousands of tiny sound-sensitive cells. These cells are known as hair cells. The vibrations entering the cochlea cause the fluid and hair cells to move, much like the movement of seaweed on the seabed when waves pass over it.
As the hair cells move, they create a small electrical charge or signal. The auditory nerve carries these signals to the brain where they are understood as sound.
For an ear to work fully and pick up sound, all of these parts must work well.
There are two main types of hearing loss:
- Nerve hearing loss which is a hearing loss in the inner ear. This usually means that the cochlea isn’t working effectively. Nerve or sensorineural hearing loss is permanent.
- Conductive hearing loss which means that sound can’t pass efficiently through the outer and middle ear into the inner ear. This is often caused by blockages such as wax in the outer ear, or fluid in the middle ear (glue ear). Glue ear is a very common condition, especially in pre-school children. Conductive hearing loss is usually temporary, but it can be permanent in some cases.
Hearing Loss in one ear only is known as unilateral hearing loss , which can also be referred to as one-sided hearing loss or single-sided deafness (SSD).
Very few children with a hearing loss have no useful hearing. Most children with hearing loss can hear some sounds at certain frequencies and loudness, and with the use of hearing aids or implants they are often able to hear more sounds.