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Cardiac-eu.org

Hearing Impairment and Deafness

Statistics

UK [1]

  • Nearly nine million people in the UK - one in seven of the population - are deaf or hard of hearing
UK [2]
  • At 31 March 2007, 54,500 people were recorded on the register of the deaf (England)
  • At 31 March 2007, 65 per cent of people on the register of the deaf were aged 75 or over (England)
  • At 31 March 2007, 164,600 people were on the register of hard of hearing (England)
  • At 31 March 2007, 65 per cent of people on the hard of hearing register were aged 75 or over (England)


Worldwide [3]

  • According to 2005 estimates by the World Health Organization (WHO), 278 million people worldwide have moderate to profound hearing loss in both ears


Types

People who are born profoundly deaf are said to be pre-lingually deaf.

People who have an acquired hearing loss (ie. have become hearing impaired after learning language) are said to be post-lingually deaf.

  • The hearing loss could have been acquired as a child after language acquisition had taken place
  • The hearing loss could have been acquired later as a natural result of ageing
  • The hearing loss could have been acquired at any age between these two extremes
  • The onset of the hearing loss could have been over a long period of time or it could have been sudden

People who have acquired hearing loss use lipreading. They rely on the spoken word. Only 30% of the spoken word can be seen at all and 40% can sometimes be seen and sometimes not.

As well as being pre or post lingual, deafness is divided into two main types. These are:

A conductive loss is one that effects the transmission of sound from outside the ear to the cochlea, which is the sensory receptor for sound. Causes may be as simple as wax in the ear canal and medical and surgical treatment can often restore the hearing to near normal. The effect of a conductive hearing loss is to reduce the volume of sound, and amplification can be of significant benefit as once the person can hear sound, particularly speech, they can understand what is being said.

A sensory-neural loss occurs in the cochlea and/or the neural pathways to the brain. The predominant condition is associated with ageing and termed presbyacusis. However, it can result from taking certain drugs, from disease (eg. rubella) and from excessive exposure to noise. The very important effect of this type of loss is not the reduction in sound level to the listener, but the fact that it is accompanied by distortion that makes the understanding of speech difficult. There is considerable variability in the degree of distortion in individuals, which is not necessarily related to their degree of loss.

Conductive and sensori-neural loss can occur together and as such are termed a mixed loss.

It must be emphasised that hearing loss is not simply a matter of reduced sensitivity that can be overcome by increasing signal loudness. Hearing loss is usually dependant on the frequency (pitch) of the sound. For instance, presbyacuis usually leads to loss of sensitivity to higher frequencies. The hearing loss of an individual is measured by audiometry which measures the loss in decibels (dB) at different frequencies. The dBHL figures below average the loss over a range of frequencies. People with hearing loss have the same pain and discomfort thresholds for sound as hearing people, so that when sound is amplified so that it can be heard it is quite easy for the sound to reach the discomfort or pain threshholds.


Levels of deafness

People are classified as having different levels of hearing loss. These are:


Mild Hearing Loss (25 - 40dBHL)

  • Some people may have difficulty in following speech mainly in noisy situations
  • Some people may wear a hearing aid. A lot of people will not


Moderate Hearing Loss (41 - 70dBHL)

  • Some people may have difficulty in following speech without a hearing aid. They may also have great difficulty in noisy situations
  • They may find both a hearing aid and lipreading skills helpful, although in a group situation they may find difficulty with background noise picked up on their hearing aid
  • Some people will be able to use the telephone if it has amplification. A specialist telephone may be needed or an inductive coupler for use with their hearing aid


Severe Hearing Loss (71 - 95dBHL)

  • Many people may have difficulty in following speech even with a hearing aid. For these people lipreading is very important. Written information also becomes very helpful
  • Most people will find difficulty in using a conventional telephone, and even a specialist telephone with extra amplification. Some may use text based telecommunication eg. a textphone such as the minicom


Profound Hearing Loss (96+ dBHL)

  • Hearing aids may be of little to no help
  • Most people in this group will depend heavily on lipreading
  • Some people will use British Sign Language if they have been deaf from birth or early childhood.
  • The written word may be the only way that some people can communicate
  • The conventional telephone will be of no use even with amplification, although a minicom may be used


Terminology

Terms which may be acceptable to the majority of deaf and hard of hearing people include:

  • Deaf
  • Hard of hearing
  • Hearing loss
  • Partially deaf
  • Hearing impaired
  • Partially hearing
  • Tinnitus (a person with tinnitus)
  • Deafened

Terms not acceptable include:

  • Deaf and dumb
  • Handicapped
  • Deaf mute


Further information


Acknowledgements: This section has been developed with the help of Mike Martin and Hearing Concern.


[1] Information Centre (2007) People Registered Deaf or Hard of Hearing Year ending 31 March 2007, in England. [accessed 30/01/08].
[2] Hearing Concern (n.d.) Medical [accessed 30/01/08].
[3] World Health Organisation (2006) Deafness and hearing impairment. [accessed 30/01/08].