1. Sound from the environment travels down the ear canal and hits the ear drum causing it to vibrate.

2. The vibration of the ear drum in turn makes the three tiny bones in the middle ear (the ‘Ossicles') vibrate.

3. The Ossicles vibrate in turn and push against the entrance to the cochlear (organ of hearing).

4. This causes the fluid in the cochlear to move, creating a wave.

5. The wave of fluid makes the tiny hair cells in the cochlear sway.

6. This swaying movement is detected by the hearing nerve (‘Auditory Nerve') and a signal is sent to the brain where it is perceived as ‘sound'.

What is hearing loss?

Hearing loss is split into groups depending upon its severity. These are: mild, moderate, severe and profound. There are three main types of hearing loss, conductive, sensorineural and mixed.

Therefore, when we categorise a hearing loss we would refer to its severity and type, for example, we may say it is a ‘mild conductive hearing loss', or a ‘severe mixed hearing loss'.

Conductive hearing loss

A conductive hearing loss occurs when there is a problem with the outer or middle ear which makes it harder for the sound to reach the cochlear.

The most common type of conductive hearing loss in children is ‘glue ear', which is a buildup of fluid in the middle ear.

If there is fluid in the middle ear then sound needs to be louder in order for it to travel through the fluid and reach the cochlear.

Conductive hearing loss caused by glue ear is very common and generally resolves after a few months, however, in some cases the conductive hearing loss persists for a longer period. In these cases, there are various management options in order to resolve the build-up of fluid, the two most common management strategies are hearing aids and grommets.

Sensorineural hearing loss

A sensorineural hearing loss is a permanent hearing loss that is caused by a problem with the cochlear.

In most cases this is because the tiny hair cells in the cochlear are damaged or missing.

This could happen for several reasons and may be congenital (from birth) or acquired (occurring after birth).

Congenital sensorineural hearing loss is mainly caused by genetic mutations or is hereditary.

The main causes of acquired sensorineural hearing loss are childhood illnesses or are a result of life-saving medical treatment in the first few days / weeks of life.

In some cases, we do not know what has caused the sensorineural hearing loss; this is called ‘idiopathic' – i.e. it has no apparent cause. Sensorineural hearing loss is permanent and the only management for this type of hearing loss is via hearing aid/s. The audiologist can refer you to a community paediatrician who can investigate the cause of your hearing loss.

Mixed hearing loss

A mixed hearing loss is a combination of a conductive hearing loss and a sensorineural hearing loss.

The most common mixed hearing loss occurs when somebody with a sensorineural hearing loss develops a case of glue ear.

So why do I need hearing aids?

People need hearing aids for different reasons, depending upon the severity of their hearing loss. For example, somebody with a mild hearing loss may struggle to hear clearly in noisy places (for example, a classroom) without hearing aids.

Somebody with a moderate or severe hearing loss may struggle to hear speech clearly (even in quiet environments) and will probably struggle to hear the TV/ telephone without hearing aids.

Somebody with a profound hearing loss will struggle to hear speech at all without hearing aids and will probably be unable to hear the smoke alarms, alarm clocks or car horns when not wearing their hearing aids.

There are different kinds of hearing aids depending upon the severity of the hearing loss. Hearing aids are very important because they help people to hear all the different pitches needed to understand and develop spoken language. If somebody cannot hear speech very well and does not wear hearing aids regularly then the ‘quality' of their speech will probably be poor as a result.

As well as this, some people need to wear hearing aids so that they can hear sounds in the environment, for example, a phone ringing. This not only allows them to hear what is happening around them, but also helps them to hear in potentially dangerous situations, for example, cars when crossing the road or a fire alarm.

One of the most important uses of hearing aids is at school. Classrooms are noisy environments and children with hearing losses will find it more difficult to hear the teacher. Wearing hearing aids will help with this and will ensure they are able to hear what is being said by the teacher. Sometimes, in schools, children may also use ‘radio aids' or ‘FM systems' to help them hear the teacher and their own voice more clearly.