The World Health Organization (WHO) has updated its fact sheet on deafness and hearing loss.
Background Information:
Normal hearing refers to hearing threshold of 25 decibels (dB) or better in both ears.
A person who is not able to hear as well as someone with normal hearing is said to have hearing loss. It may be mild, moderate, severe, or profound; can affect one or both ears, and leads to difficulty in hearing conversational speech or loud sounds.
‘Hard of hearing’ refers to people with hearing loss ranging from mild to severe. People who are hard of hearing usually communicate through spoken language and can benefit from hearing aids, cochlear implants, and other assistive devices as well as captioning.
‘Deaf’ people mostly have profound hearing loss, which implies very little or no hearing. They often use sign language for communication.
Disabling hearing loss refers to hearing loss greater than 40 decibels (dB) in the better hearing ear in adults and a hearing loss greater than 30 dB in the better hearing ear in children.
The majority of people with disabling hearing loss live in low- and middle-income countries.
Causes of Hearing Loss
Congenital causes
Congenital causes may lead to hearing loss being present at or acquired soon after birth. Hearing loss can be caused by hereditary and non-hereditary genetic factors or by certain complications during pregnancy and childbirth, including:
- maternal rubella, syphilis or certain other infections during pregnancy;
- low birth weight;
- birth asphyxia (a lack of oxygen at the time of birth);
- inappropriate use of particular drugs during pregnancy, such as aminoglycosides, cytotoxic drugs, antimalarial drugs, and diuretics;
- severe jaundice in the neonatal period, which can damage the hearing nerve in a newborn infant.
Acquired causes
Acquired causes may lead to hearing loss at any age, such as:
- infectious diseases including meningitis, measles and mumps;
- chronic ear infections;
- collection of fluid in the ear (otitis media);
- use of certain medicines, such as those used in the treatment of neonatal infections, malaria, drug-resistant tuberculosis, and cancers;
- injury to the head or ear;
- excessive noise, including occupational noise such as that from machinery and explosions;
- recreational exposure to loud sounds such as that from use of personal audio devices at high volumes and for prolonged periods of time and regular attendance at concerts, nightclubs, bars and sporting events;
- ageing, in particular due to degeneration of sensory cells; and
- wax or foreign bodies blocking the ear canal.
Among children, chronic otitis media is a common cause of hearing loss.
Key Messages:
Over 5% of the world’s population – or 466 million people – has disabling hearing loss (432 million adults and 34 million children).
It is estimated that by 2050 over 900 million people – or one in every ten people – will have disabling hearing loss.
Hearing loss may result from genetic causes, complications at birth, certain infectious diseases, chronic ear infections, the use of particular drugs, exposure to excessive noise, and ageing.
1.1 billion young people (aged between 12–35 years) are at risk of hearing loss due to exposure to noise in recreational settings.
One of the main impacts of hearing loss is on the individual’s ability to communicate with others. Spoken language development is often delayed in children with unaddressed hearing loss.
Unaddressed hearing loss poses an annual global cost of US$ 750 billion. Interventions to prevent, identify and address hearing loss are cost-effective and can bring great benefit to individuals.
People with hearing loss benefit from
- early identification;
- use of hearing aids, cochlear implants and other assistive devices;
- captioning and sign language; and
- other forms of educational and social support.
Overall, it is suggested that half of all cases of hearing loss can be prevented through public health measures.
In children under 15 years of age, 60% of hearing loss is attributable to preventable causes. This figure is higher in low- and middle-income countries (75%) as compared to high-income countries (49%). Overall, preventable causes of childhood hearing loss include:
- Infections such as mumps, measles, rubella, meningitis, cytomegalovirus infections, and chronic otitis media (31%).
- Complications at the time of birth, such as birth asphyxia, low birth weight, prematurity, and jaundice (17%).
- Use of ototoxic medicines in expecting mothers and babies (4%).
- Others (8%)
Prevention
Some simple strategies for prevention of hearing loss include:
- immunizing children against childhood diseases, including measles, meningitis, rubella and mumps;
- immunizing adolescent girls and women of reproductive age against rubella before pregnancy;
- preventing cytomegalovirus infections in expectant mothers through good hygiene; screening for and treating syphilis and other infections in pregnant women;
- strengthening maternal and child health programmes, including promotion of safe childbirth;
- following healthy ear care practices;
- reducing exposure (both occupational and recreational) to loud sounds by raising awareness about the risks; developing and enforcing relevant legislation; and encouraging individuals to use personal protective devices such as earplugs and noise-cancelling earphones and headphones.
- screening of children for otitis media, followed by appropriate medical or surgical interventions;
- avoiding the use of particular drugs which may be harmful to hearing, unless prescribed and monitored by a qualified physician;
- referring infants at high risk, such as those with a family history of deafness or those born with low birth weight, birth asphyxia, jaundice or meningitis, for early assessment of hearing, to ensure prompt diagnosis and appropriate management, as required;
- implementing the WHO-ITU global standard for personal audio systems and devices. If adhered to, the standard could help prevent hearing loss due to listening practices that are harmful to hearing; and
- educating young people and population in general on hearing loss, its causes, prevention and identification.
Pre-school, school and occupational screening for ear diseases and hearing loss is an effective tool for early identification and management of hearing loss.
Screening can be done using the hearWHO app. This app can be downloaded and used by adults to check and track their hearing regularly. It can also be used by health workers to screen people in the community with a view to referring them for hearing testing, when indicated.
Useful Links:
Link to the updated fact sheet:
https://www.who.int/news-room/fact-sheets/detail/deafness-and-hearing-loss
Link to previous article on WHO-ITU standards:
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