Types & Effects of Deafness
The words "deafness" and "deaf" are contested concepts. That is, they mean different things to different people. There is an estimated demographic figure of 364 million deaf and hard of hearing in the world. Of this large number, only a few million are considered "deaf" and the remainder are "hard of hearing." However, statistics are confused by variation in the strict definition and colloquial usage of “deaf” and “hard of hearing- some people labelled by themselves or others as "deaf" may actually be "hard of hearing," and some "hard of hearing" people may actually be "deaf."
In the early 1900's, it was common to refer to the "Deaf and Dumb" - "dumb" meaning "not able to communicate verbally". However, as "dumb" came to mean "silly", "stupid", deaf people rejected the phrase. In an effort to be politically correct, the phrase became "Deaf/Mute". But with the increasing push for deaf people to learn to speak, this phrase also became incorrect.
In the late 1900's the labels "deaf" and "hard of hearing" were employed as subcategories of the term "hearing-impaired." During that time, it was used as a generic term that was applicable to anybody with any degree of hearing loss. However, some deaf people objected to the description of their hearing status as "impaired" because they felt that the term also implied that the person was "impaired." Such degrading terms can actually cause depression and anxiety among deaf people and, thus, this generic label is now discouraged.
The deaf and hard of hearing community is very diverse, differing greatly on the cause and degree of hearing loss, age at the onset, educational background, communication methods, and how they feel about their hearing loss. How a person "labels" themselves in terms of their hearing loss is personal and may reflect identification with their relationship with the deaf community or merely how their hearing loss affects their ability to communicate. They can either be deaf, Deaf (with a capital "D"), or hard of hearing.
There are three Models of Deafness - Medical Modal, Social Modal and Cultural Modal - and each model is based upon a different definition and understanding of "deafness". Part of the difficulty of understanding deafness is due to the fact that there are many causes, many types, varied levels, and also individual abilities, environments and differences.
The Deafness Spoke addresses issues related to the medical model of deafness, that is, the impact of hearing loss to an individual's audiological experience. This includes the physiological aspects of deafness, usually referred to as a weakness or failure of hearing, and uses terms such as "hearing loss" or "Hearing impairment", "handicap" and "disability". It also includes definitions, causes, types, effects, and incidence in children and adults.
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[Edit]1 Definitions
The Online Medical Dictionary1, describing the medical model of deafness, defines the following terms:
- "Deafness: A condition in which the sense of hearing in both ears is not functional for ordinary purposes of life. The hearing level for speech is approximately 71 decibels I.s.o. (international organization for standardization) or 61 db a.s.a. (American Standards Association) or greater."
- "Hearing Impairment: A reduction in the ability to perceive sound; may range from slight to complete deafness."
- "Bilateral Hearing Loss?: Partial hearing loss in both ears."
- "Central Hearing Loss?: Hearing loss due to central nervous system disease, anywhere in the auditory pathways from the cochlear nucleus of the pons to the auditory cortex."
- "Conductive Hearing Loss: Hearing loss due to interference with the acoustic transmission of sound to the cochlea. The interference is in the outer or middle ear."
- "Functional Hearing Loss?: Hearing loss without a physical basis."
- "High-Frequency Hearing Loss: Hearing loss in frequencies above 1000 hertz."
- "Noise-Induced Hearing Loss: Hearing loss from exposure to noise. The loss is often in the frequency range 4000-6000 hertz."
- "Partial Hearing Loss?: A condition in which the sense of hearing, although defective, is functional with or without a hearing aid. The hearing level for speech is approximately 40-70 decibels I.s.o. (international organization for standardization) or 30-60 db a.s.a. (American Standards Association)."
- "Sensorineural Hearing Loss?: Hearing loss resulting from damage to the sensory mechanism internal from the oval and round windows."
All use of deafness terms in the Deafness Spoke will relate to medical definitions.
[Edit]2 Symptoms of Hearing Loss and Deafness
Recognising hearing loss, particularly in children, can be problematic. Many children are unrecognised or misdiagnosed as autistic or intellectually impaired.
Signs and symptoms that should motivate further investigation include:
* Lack of startle response to sudden (particularly unexpected) noise * Lack of response to hand clapping * Delayed speech in children, or unclear speech, mumbling, and shouting in adults * Person apparently lost in their own private world
Hearing loss should also be suspected if a child has begun to learn spoken language, and then begins to regress and lose the speech they had.
[Edit]2.1 Measurement of Hearing Loss
Sound is measured by its loudness or intensity, measured in decibels (dB), and its frequency or pitch, measured in hertz (Hz). Hearing impairments can occur in either loudness or intensity, in only one ear or in both ears. Hearing loss is described as mild, moderate, severe, or profound. If a person is referred to as "[Deaf]"*, it is meant they have no hearing at all, and often have not acquired verbal speech skills considered "normal". If they are called "[Hearing Impaired]"* it generally means they can speak reasonably clearly, and that often implies a greater degree of hearing (although these labels are far from definite). Traditionally, "[Hard of Hearing]"* has been a term reserved for older people who are losing their hearing, but it is now becoming more politically correct to use this label rather than "hearing impaired".
Phonak has a wonderful collection of hearing loss demos
(http://www.phonak.com/consumer/hearing/hearinglossdemo.htm), demonstrating how things sounds with no, mild and moderate hearing loss in different environments
- when the label is used by medical staff, or by members of the community who have a medical model of deafness
[Edit]3 Prevalence of Hearing Loss and Deafness
Statistics on the prevalence of hearing loss, hearing impairment or deafness are not widely available. Governments have not been reliable in collecting data relating to hearing loss and deafness, and for a variety of reasons many people do not seek audiological assistance.
According to the Australian Bureau of Statistics3, around 11% of the Australian population are partially or completely deaf, varying from 2% prelingually to 53% of men and 35% of women aged over 75 years. However, in the 2004 report from Australian Institute of Health and Welfare4, it is suggested that up to 22% of the population has a hearing loss. They also suggested that up to 17% of the population had a hearing loss significant enough to impact the discrimination of speech.
NOTE: The term 'prevalence' of Deafness usually refers to the estimated population of people who are managing Deafness at any given time. The term 'incidence' of Deafness refers to the annual diagnosis rate, or the number of new cases of Deafness diagnosed each year. ( More information about prevalence and incidence statistics. (http://www.wrongdiagnosis.com/admin/preval.htm))
[Edit]4 Causes of Permanent Hearing Impairment and Deafness
There are many causes of permanent hearing impairment and deafness. Genetic factors such as Alport Syndrome, and, most commonly, Connexin26 are estimated to be the cause of around 50% of hearing loss.2 Congenital Deafness? (occuring at birth) is usually either genetic or caused by illnesses in the pregnant mother such as Rubella, Influenza, Glandular Fever, Toxoplasmosis, Syphilis, HIV, Cytomegalo, Herpes and other viruses, and exposure to drugs known as [http://www.deafhub.com/index.php?id=1064&no_cache=1&tx_drwiki_pi1[keyword]=Toxins Ototoxins].
People who are late deafened? are said to have [Acquired Deafness], which can be caused by genetic factors, but may also be caused by Infection, Trauma, [http://www.deafhub.com/index.php?id=1064&no_cache=1&tx_drwiki_pi1[keyword]=Toxins | Ototoxins], Occupational Hazards, Disease or Age.
[Edit]5 Causes of Temporary Hearing Loss and Deafness
Temporary Deafness? or hearing loss can be caused by something as simple as the build-up of wax in the ear canal. Similarly, a foreign body such as an insect or bead lodged in the ear canal, blocked eustachian tubes, ear infections and allergies can cause hearing loss, as can a scarred eardrum from repeated infections. Trauma or injury to the head, perforated eardrums from trauma or infection, and reaction to medications are also a cause of temporary deafness.
[Edit]6 Classifications of Deafness
There are four classifications of deafness, according to the location of the impediment.
Conductive hearing losses affect the outer or middle ear, and can be caused by diseases or obstructions in the conduction pathways to the inner ear. Conductive hearing losses usually affect all frequencies of hearing evenly and do not result in severe losses. A person with a conductive hearing loss usually gets a significant amount of assistance from hearing aids. Also, medical or surgical interventions often greatly lesson the conductive hearing loss.
Sensorineural hearing losses result from damage to the sensory hair cells of the cochlea, or the acoustic nerves. Hearing losses can range from mild to profound, and they often impact a person's ability to hear some frequencies more than others. Consequently, sensorineural hearing loss may result in distorted sounds. As hearing aids simply amplify, not refine sound*, sometimes they do not provide any great assistance. Industrial Deafness, caused by excessive noise, and aging both result in this type of hearing loss.
A mixed hearing loss refers to a combination of conductive and sensorineural loss and means that a problem occurs in both the outer or middle and the inner ear.
A central hearing loss occurs when there is damage or impairment to the nerves or of the central nervous system, either in the pathways to the brain or in the brain itself.
- Newer hearing aids are being developed that can amplify different frequencies to different levels, and to "intelligently" select sounds based on the programming of the aid, but they are unable to correct the distortion.
[Edit]7 Other Types of Deafness
- Congenital Deafness
- Sudden Deafness
- Industrial Deafness
- Tinnitus
- Auditory Neuropathy/Dys-synchrony
- Central Auditory Processing Disorder
[Edit]8 Effects of Hearing Loss and Deafness
If hearing loss or deafness is not recognised quickly it has serious repercussions for relationships with their families; language and literacy, and as a result, concept and speech development; education and training; employment; and consequently increases the possibility for discrimination in the workplace and in the wider community.
[Edit]9 Treatment of Hearing Loss - Hearing (Re)Habilitation
[Edit]9.1 Definition
Hearing habilitation or rehabilitation is the process of accessing the residual hearing of a Deaf/HoH person through the use of assistive devices and/or auditory training techniques. The term “habilitation” (from the Latin habilitare, “to make able to”) is generally used with children who were prelingually deafened – that is, before acquiring spoken language. “Rehabilitation” is used for children and adults who become Deaf/HoH after learning speech/language.
[Edit]9.2 Purpose of Habilitation
Hearing habilitation seeks to help the deaf/hard of hearing child access information from sound as much as possible. The purpose of accessing sound varies. Hearing parents often want their Deaf/HoH children to understand and produce speech sufficiently well to communicate in the hearing world. They choose spoken English as the child’s intended primary language, since it matches their own. Other parents envision sound as an adjunct to sign language and/or speech reading; their chosen language may be sign or spoken English. Still others, particularly those whose children have profound hearing loss, are more concerned about the child’s safety. They want the child to be able to hear warning sirens, trucks backing up, car horns, and fire alarms. Speech is not as important to these parents, so they usually choose sign language as the child’s main form of communication.
[Edit]9.3 Purpose of Rehabilitation
For those who became deaf or acquire hearing impairments after learning spoken language, the primary goal of rehabilitation is to recover the ability to communicate verbally. Individuals who experience hearing loss in adolescence or older usually do not have great difficulty with speech production, since they are familiar with the movements necessary and receive feedback from the muscles to determine accuracy. Younger children, whose speech patterns are not as defined, may have more trouble producing intelligible speech (depending on the degree of hearing loss). Also, they are still learning language, so they need extra attention in that area of development. For both groups, speech perception is essential.
However, some individuals, particularly in the case of profoundly deafened young children, choose to change from spoken English to sign language as the preferred language. In that case, as indicated above, rehabilitation may focus on hearing as an adjunct to sign or as a means of increased safety.
[Edit]9.4 Issues to Consider
Choices about (re)habilitation will depend, in part, on the individual’s or the parents’ attitude about the meaning of deafness. If being unable to hear is viewed as a liability that must be corrected at all costs (medical model), the most likely choice will be a cochlear implant or a powerful hearing aid along with therapy that emphasizes sound and may completely exclude sign. However, if it is viewed as part of an identity – a quality that allows a person to participate fully in Deaf culture (cultural model) – then hearing (re)habilitation may be minimal and will focus on sign language. Of course, those are the extremes, but attitudes may fall anywhere along the spectrum between the two.
[Edit]10 Prevention of Hearing Loss
Hearing is a precious sense and must be conserved much like a natural resource; when it is all used up and gone, it's gone for good. This is why hearing conservation and protection is important. Hearing Conservation is the deliberate attempt to protect and conserve as much of people's hearing as possible over their lifetime.
[Edit]11 Quick Facts About Hearing Impairment and Deafness
According to 2005 estimates by the World Health Organization (WHO)5,
- 278 million people worldwide have moderate to profound hearing loss in both ears.
- 80% of deaf and hearing-impaired people live in low- and middle-income countries.
- The number of people worldwide with all levels of hearing impairment is rising mainly due to a growing global population and longer life expectancies.
- Chronic middle ear infection is the main cause of mild to moderate hearing impairment in children.
- The impact of hearing impairment on a child's speech, language, education and social integration depends on the level and type of hearing impairment, and the age of onset, especially if it begins before the age when speech normally develops.
- In developing countries, fewer than 1 in 40 people who would benefit from a hearing aid have one.
- Current annual production of hearing aids is estimated to meet less than 10% of global need.
- 50% of deafness and hearing impairment is avoidable through prevention, early diagnosis, and management.
[Edit]12 References
- On-line Medical Dictionary, © 1997-98 Academic Medical Publishing & CancerWEB, http://cancerweb.ncl.ac.uk/omd/
- Keats, Bronya J. B., Popper, Arthur N., Fay, Richard R., (2002) Genetics and Auditory Disorders, Springer
- ABS 2002c. 2001 National Health Survey: summary of results. ABS Cat. No. 4364.0. Canberra: ABS.
- Australian Institute of Health and Welfare 2004. Australias Health 2004. Canberra: AIHW.
- World Health Organisation, "Deafness and hearing impairment", [1] (http://www.who.int/mediacentre/factsheets/fs300/en/index.html), last accessed 5 December, 2007
