Types of deafness
Medically, there are two major types of deafness.
- Conductive deafness, where sound cannot pass through the outer or middle ear
- Sensorineural deafness, where the cause of the deafness is in the cochlea or in the auditory (hearing) nerve. Sensorineural deafness often reduces the quality of sound as well as its loudness.
Types of deafness and common medical diagnoses are described in a factsheet 'Ears and Ear Problems' from the RNID - Royal National Institute for Deaf People. Their information and resources section also lets you hear what tinnitus can sound like.
While medical labels are not a particularly useful tool for understanding an individual student’s learning or communication requirements, or for making your teaching more appropriate for deaf students, you may come across some of the following medical terms.
Tinnitus: A condition that can affect both deaf and hearing people, who hear buzzing, ringing or hissing sounds. Tinnitus can make sleep difficult, and it has a pervasive and detrimental affect on quality of life. It can interfere with hearing and cause significant anxiety and stress. Many people experience tinnitus at some point in their life, but for some tinnitus is a permanent condition.
Ménières disease: One of a number of conditions that can cause extreme dizziness and balance problems. It is a long-term, progressive, inner-ear condition that can also cause bouts of hearing loss, over-sensitivity to sound and nausea. The bouts can last from a few minutes to 24 hours with intervening periods of remission: they may cause great anxiety and distress.
Cochlear implant: A device that does not restore normal hearing but can give a sensation of sound for some severely or profoundly deaf people who get little or no benefit from a hearing aid. It can be particularly effective for someone who lost their hearing after acquiring spoken language. For a cochlear implant to work, the auditory nerve must be functional even though the function of the inner ear is impaired. The implant consists of two parts, one worn externally (usually behind the ear) and the other surgically implanted inside the ear. The implant is ‘tuned’ and the recipient needs a period of adjustment before getting maximum benefit. The implant destroys what natural hearing may have been present, so a person with an implant can no longer use a hearing aid to augment hearing. Some deaf people who consider themselves members of a linguistic minority have concerns about the use of cochlear implants.
Definitions associated with deafness
Many different terms are used to describe deafness and it is useful to understand what they mean. Some overlap in meaning, and others are no longer used by deaf people, although you may still find reference to them. If you are not sure which term to use, check with the deaf person you are talking to.
Deaf: deaf with a small d simply refers to the medical condition of hearing loss. However most people who use BSL refer to themselves as Deaf. This is a political and cultural term of belonging to the Deaf community. It is used in the same way that people who belong to a national, cultural or religious group would describe themselves, for example as French or Muslim. It is for this reason that many Deaf people do not define themselves as disabled, rather they describe themselves as belonging to a cultural or linguistic minority.
Hard of hearing: A general term used to describe people with a range of hearing loss and communication needs.
Hearing impaired: No longer commonly used as it has been largely replaced by deaf and hard of hearing.
Deafblind: This term applies to people with dual sensory loss. Some people who are deafblind have no hearing or vision, others have a degree of hearing loss and visual impairment. There are about 23,000 deafblind people in the UK. Usher's syndrome is an inherited condition which involves degeneration of the retina and is a major cause of deafblindness. Vision degenerates unpredictably, but symptoms can include night blindness, a narrowing of the field of vision, and loss of central acuity that leads to an inability to read print.
You may also come across other terms that indicate onset of deafness.
Pre-lingually deaf: Someone who was born severely or profoundly deaf - most likely to communicate through sign language.
Deafened: A person who was born hearing and subsequently became severely or profoundly deaf.
Onset of deafness is likely to impact on a student’s previous experience of study as a hearing person, and on the study skills and strategies that they have developed. Someone who is pre-lingually deaf has different skills and needs from a person who studied quite recently as a hearing person and then become deafened.