Deafness and hearing impairment
- In 2004, over 275 million people globally had moderate-to-profound hearing impairment, 80% of them in low- and middle-income countries.
- Infectious diseases such as meningitis, measles, mumps and chronic ear infections can lead to hearing impairment. Other common causes include exposure to excessive noise, head and ear injury, ageing and the use of ototoxic drugs.
- Half of all cases of deafness and hearing impairment are avoidable through primary prevention.
- A large percentage can be treated through early diagnosis and suitable management.
- Depending on the cause of hearing loss, it may be treated medically, surgically or through devices such as hearing aids and Cochlear Implants.
- Production of hearing aids meets less than 10% of global need. In developing countries, fewer than 1 out of 40 people who need a hearing aid have one.
In 2004, over 275 million people globally had moderate-to-profound hearing impairment, 80% of them in low- and middle-income countries.
Types of hearing impairmentDeafness refers to the complete loss of hearing in one or both ears. Hearing impairment refers to both complete and partial loss of the ability to hear.
There are two types of hearing impairment, according to which part of the ear is affected.
- Conductive hearing impairment is a problem in the outer or middle ear. It is often medically or surgically treatable. A common example is chronic middle ear infection.
- Sensorineural hearing impairment is a problem with the inner ear or the hearing nerve. It is mostly permanent and requires rehabilitation such as the use of a hearing aid.
Causes of hearing impairment and deafness
Congenital causes which may lead to deafness present at or acquired soon after birth
- Hereditary hearing loss where deafness is inherited from a parent. If one or both parents or a relative is deaf, there is a higher risk that a child could be born deaf.
- Hearing impairment may also be caused by problems during pregnancy and childbirth. These include:
- low birth weight: either due to premature birth or a 'small for date' baby;
- birth asphyxia or conditions during birth where a baby suffers lack of oxygen;
- rubella, syphilis or certain other infections in a woman during pregnancy;
- inappropriate use of ototoxic drugs (a group of more than 130 drugs, such as the antibiotic gentamicin) during pregnancy;
- severe jaundice, which can damage the hearing nerve in a newborn baby.
Acquired causes which can lead to hearing loss at any age
- Infectious diseases such as meningitis, measles and mumps can lead to hearing impairment, mostly in childhood, but also later in life.
- Chronic ear infections, which commonly present as discharging ears can lead to hearing loss. In certain cases this condition can also lead to serious, life threatening complications, such as brain abscess, meningitis etc.
- Use of ototoxic drugs at any age, including some antibiotic and anti-malarial drugs, can damage the inner ear.
- Head injury or injury to the ear can cause hearing impairment.
- Excessive noise, including working with noisy machinery, exposure to loud music or other loud noises, such as gunfire or explosions, can damage the inner ear and weaken hearing ability.
- Age related hearing loss (presbyacusis): As people age, there may be a deterioration in the levels of hearing due to ageing.
- Wax or foreign bodies blocking the ear canal can cause hearing loss at any age. Such hearing loss is usually mild and can be readily corrected.
Social and economic burdenHearing impairment can impose a heavy social and economic burden on individuals, families, communities and countries.
Hearing impairment in children may delay development of language and cognitive skills, which may hinder progress in school. The extent of delay depends on the degree of hearing loss. In adults, hearing impairment often makes it difficult to obtain, perform, and keep jobs. Hearing-impaired children and adults are often stigmatized and socially isolated.
The poor suffer more from hearing impairment because they cannot afford the preventive and routine care to avoid hearing loss. They often do not have access to ear and hearing care services and are unable to obtain suitable hearing aids to make the disability manageable. Hearing impairment may also make it more difficult for them to escape poverty by hindering progress in school or in the workplace and by isolating them socially.
For countries, the cost of special education and lost employment due to hearing impairment can burden the economy.
PreventionHalf of all cases of deafness and hearing impairment are avoidable through primary prevention. A large percentage can be treated through early diagnosis and suitable management.
Solutions to hearing impairment focus on primary ear and hearing care in order to promote the concepts of prevention, early detection, management and rehabilitation.
Some simple strategies for prevention include:
- immunizing children against childhood diseases, including measles, meningitis, rubella and mumps;
- immunizing of adolescent girls and women of child-bearing age against rubella before pregnancy;
- screening and treating syphilis and other infections in pregnant women;
- improving antenatal and perinatal care, including promotion of safe deliveries;
- avoiding the use of ototoxic drugs, unless prescribed by a qualified physician and properly monitored for correct dosage;
- referring high risk babies (such as those with family history of deafness, those born with low birth weight or suffering birth asphyxia, jaundice, meningitis etc) for assessment of hearing, diagnosis and treatment, where required;
- reducing exposure (both occupational and recreational) to loud noises by awareness creation, use of personal protective devices, and implementation of suitable legislation.
In babies and young children, early detection and treatment prevents problems with language development and progress in school.
Depending on the cause of hearing loss, it may be treated medically, surgically or through devices such as hearing aids and Cochlear Implants. Making affordable and properly fitted hearing aids and follow-up services available and accessible can benefit persons with hearing loss. Production of hearing aids meets less than 10% of global need. In developing countries, fewer than 1 out of 40 people who need a hearing aid have one.
WHO activitiesWHO assists Member States in reducing and eventually eliminating avoidable hearing impairment and deafness through integration of primary ear and hearing care into the primary health care system of the country. Proposed measures include:
- encouraging and guiding Member States in developing and implementing national plans for primary ear and hearing care programmes;
- providing technical resources and guidance for training of health care workers on primary ear and hearing care;
- developing and disseminating guidelines against the major preventable causes of hearing impairment;
- building partnerships to provide affordable hearing aids and services to people in need;
- raising awareness about the level, causes and costs of hearing impairment and the opportunities for prevention;
- developing a global database on deafness and hearing impairment to demonstrate the size and the cost of the problem.
For more information contactWHO Media centre
Telephone: +41 22 791 2222