We've created this glossary to explain important words and phrases used in our website and printed materials. We know people are more comfortable with some words than others when describing their own deafness or hearing loss. It's not a definitive list - please suggest any words or phrases you think are important:

Jump to pages within this section:

A - C


Acute otitis media

Acute otitis media (glue ear(external link, opens new window)) is a short-term ear infection that often comes on suddenly. Symptoms are a build-up of fluid in the middle ear, which can get infected.

Adaptive directionality

Digital hearing aids have systems (directional microphones and noise reduction) that detect if you are in a quiet or noisy environment and the source of sound. The hearing aid adjusts its settings to optimise performance.

Aminoglycoside antibiotics

Aminoglycoside is the name given to a group of antibiotic drugs that are most likely to cause hearing loss. These include gentamycin, streptomycin and neomycin. Aminoglycoside antibiotics are usually only used to treat life threatening bacterial infections, such as tuberculosis.

Analogue hearing aids

Analogue hearing aids have a microphone that picks up sound and converts the sound into small electrical signals. These electrical signals are then amplified (made louder) and fed into an earphone on the hearing aid so you can hear them. They have largely been replaced by digital hearing aids.


An audiogram is a chart that represents a person's hearing ability, determined by a hearing test. Audiologists use audiograms to help judge whether a person has a hearing loss and what type of help they need.


Audiologists specialise in identifying and assessing hearing and balance problems. They recommend and provide appropriate support, products and treatments to help alleviate the effects of hearing loss.

Audiologists work both privately and for the NHS.

Auditory nerve

The auditory nerve (also known as the cochlear or acoustic nerve) carries signals from the cochlea to the brain.

Auditory processing disorder

Disorder that affects the processing of auditory information within the brain. APD is used as an umbrella for all those that are thought to affect this processing.

Usually someone who has normal functioning outer, middle and inner ear; however they are unable to process sounds in the same way that others do. Typically someone would present with difficulties recognising and interpreting sounds, especially speech sounds.


Behind-the-ear (BTE) hearing aids

BTE aids have an ear mould that fits inside the ear, while the rest of the aid rests behind the ear. Some models have twin microphones, to switch between all-round sound and a more directional setting that can help focus sound in noisy places.

Bone conduction hearing aids

Bone conductin hearing aids are for people with conductive hearing loss or people who can't wear conventional hearing aids. They deliver sound through the skull via vibrations.

Body worn hearing aids

Body worn hearing aids have a small box that clips to clothes or fits inside a pocket. This is connected by a lead to the earphone. Some people find the controls less fiddly than those on smaller hearing aids. Body worn aids can be very powerful.

Brain stem implants

Brain stem implants can improve hearing in patients with neural hearing loss, which can be caused by cancer of the auditory (hearing) nerve or an auditory nerve that failed to develop properly. Implants convert sound into electrical impulses that stimulate the brain directly, bypassing the auditory nerve.


Channels / bands

When sounds are processed in a digital hearing aid, the sound spectrum is split into channels or bands. The amplification in these bands can be adjusted independently to more accurately suit an individual's hearing loss.


Condition of the middle ear(PDF 636, opens new window) that generally starts with a hole in the ear drum; usually in the upper part of the drum. This can become infected and the ear drum sheds dead skin which mixes with other debris in the ear to form a mass - called a cholesteatoma.

If left untreated this mass can grow causing damage to different parts of the ear; leading to hearing loss, tinnitus and sometimes balance problems. In very severe cases it can cause meningitis or brain infections, although this is very rare.

Chronic otitis media

Chronic otitis media is an infection located in the middle ear(external link, opens new window). It can either last for a long time or be recurring. Symptoms are a build-up of fluid in the middle ear.


The cochlea is the hearing ‘organ’ of the inner ear. It is a fluid filled chamber. When sound waves enter the cochlea from the middle ear, the fluid vibrates causing tiny sensory hair cells to pick up the movement and trigger an electrical signal in the auditory nerve. This passes signals to the brain where they are heard as sound.

Cochlear implants

Cochlear implants provide a sensation of hearing to people who are severely to profoundly deaf. The implant consists of a microphone and a transmitter outside the head, which send signals to an implanted receiver under the skin. This in turn sends signals to electrodes implanted in the cochlea. When the electrodes receive a signal, tiny electric currents stimulate the auditory nerve, which carries sound from the cochlea to the brain.

Completely-in-the-ear-canal (CIC) hearing aids

CIC's are even smaller than ITE aids, so they are less visible. They are unlikely to be suitable if you have severe hearing loss, or frequent ear infections


Hearing aids amplify weak sounds to a level that the user can hear. They also ensure that strong sounds are not amplified too much to avoid discomfort. Compression is the system that manages this, and enables a user to listen comfortably to quiet and loud sounds in quick succession without having to manually change settings.

Conductive deafness

Conductive deafness is when sound cannot pass freely through the outer or middle ear. This is usually caused by a blockage in the outer or middle ear from an infection or wax build-up. Depending on the cause, conductive hearing loss can be temporary or permanent, and can sometimes be cured with minor surgery or medication.

Cytomegaloviral disease

Cytomegalovirus (CMV) is part of the herpes family of viruses. Once infected the virus is permanently carried, as no cure exists. If a woman becomes infected for the first time during pregnancy, there is a risk she may pass the infection to the unborn baby. Infection in the baby is known as congenital CMV and can cause hearing loss or deafness.

Research breakthrough. Human stem cells restore hearing.