Glossary of Terms on Deafness and Deafblindness
Acquired hearing loss
Hearing loss that was not present at birth but developed later, either during childhood or adulthood.
The three types of acquired hearing loss are acoustic trauma, conductive hearing loss and sensorineural hearing loss.
Noise-induced hearing loss
Damage to the ear from loud noises occurs when part of the delicate inner structures of the ear becomes damaged. After prolonged exposure to loud noises, the cells inside the spiral part of the cochlea become inflamed. The loudness of the noise and the length of time that you are exposed to it are important factors in hearing loss. People most at risk are those:
- who work with noisy equipment, such as pneumatic drills or compressed-air hammers;
- who work in environments where there is loud music, such as nightclub staff;
- who listen to music at a high volume through headphones;
- who have been close to an explosion (acoustic trauma).
Conductive hearing loss
Conductive hearing loss occurs when sounds are unable to pass into the inner ear. This is usually due to a blockage, such as having
- too much ear wax,
- from a build-up of fluid caused by glue ear
- an ear infection like otitis media: Normally people recover from it completely but children who suffer from chronic otitis media have higher risks of developing conductive and sensorineural hearing loss.
- a perforated eardrum – where the eardrum is torn or has a hole in it,
- otosclerosis – an abnormal growth of bone in the middle ear which causes the inner hearing bone (the stapes) to be less mobile and less effective at transmitting sound.
Sensorineural hearing loss
- age-related hearing loss (presbycusis)
- genetic hearing loss – some people may be born deaf or become deaf over time due to a genetic abnormality, although there is not always a family history
- prolonged exposure to loud noises which causes damage to the inner ear
- viral infections of the inner ear, such as mumps or measles
- viral infections of the auditory nerve, such as mumps or rubella
- Ménière's disease – where a person suffers with vertigo (spinning dizziness), hearing loss which can come and go, tinnitus and a feeling of blockage in the ear
- acoustic neuroma – a non-cancerous (benign) growth on or near the auditory nerve
- meningitis – a protective coating called the meninges covers the brain. Meningitis is when a germ infects this protective coating. The infection may cause inflammation in the sufferer's brain. As the inflammation heals it may cause scarring.
- encephalitis – inflammation (swelling) of the brain
- multiple sclerosis – a neurological condition that affects the central nervous system (the brain and spinal cord)
- stroke – where the blood supply to the brain is cut off or interrupted
- Ototoxic (damaging to the auditory system) medication (chemotherapy), which is often used to treat cancer, and certain antibiotics such as Aminoglycosides can also damage the cochlea and the auditory nerve, causing sensorineural hearing loss.