Deafness and Hearing Loss

Over 5% of the world’s population – or 430 million people – require rehabilitation to address their disabling hearing loss (including 34 million children). It is estimated that by 2050 over 700 million people – or 1 in every 10 people – will have disabling hearing loss.

Disabling hearing loss refers to hearing loss greater than 35 decibels (dB) in the better hearing ear. Nearly 80% of people with disabling hearing loss live in low- and middle-income countries. The prevalence of hearing loss increases with age, among those older than 60 years, over 25% are affected by disabling hearing loss.

Hearing loss and deafness

A person who is not able to hear as well as someone with normal hearing – hearing thresholds of 20 dB or better in both ears – is said to have hearing loss. Hearing loss may be mild, moderate, severe or profound. It can affect one ear 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.

Causes of hearing loss and deafness

Although these factors can be encountered at different periods across the life span, individuals are most susceptible to their effects during critical periods in life.

Prenatal period

• genetic factors including hereditary and non-hereditary hearing loss
• intrauterine infections – such as rubella and cytomegalovirus infection.

Perinatal period

• birth asphyxia (a lack of oxygen at the time of birth
• hyperbilirubinemia (severe jaundice in the neonatal period)
• low-birth weight
• other perinatal morbidities and their management.

Childhood and adolescence 

• chronic ear infections (chronic suppurative otitis media)
• collection of fluid in the ear (chronic nonsuppurative otitis media)
• meningitis and other infections.

Adulthood and older age 

• chronic diseases
• smoking
• otosclerosis
• age-related sensorineural degeneration
• sudden sensorineural hearing loss.

Factors across the life span 

• cerumen impaction (impacted ear wax)
• trauma to the ear or head
• loud noise/loud sounds
• ototoxic medicines
• work related ototoxic chemicals
• nutritional deficiencies
• viral infections and other ear conditions
• delayed onset or progressive genetic hearing loss.

The impact of unaddressed hearing loss

When unaddressed, hearing loss impacts many aspects of life at individual level:

• communication and speech;
• cognition;
• social isolation, loneliness and stigma;
• impact on society and economy;effects on years lived with disability (YDLs) and disability adjusted life years (DALYs); and
• education and employment: In developing countries, children with hearing loss and deafness often do not receive schooling. Adults with hearing loss also have a much higher unemployment rate. Among those who are employed, a higher percentage of people with hearing loss are in the lower grades of employment compared with the general workforce.

WHO estimates that unaddressed hearing loss poses an annual global cost of US$ 980 billion. This includes health sector costs (excluding the cost of hearing devices), costs of educational support, loss of productivity and societal costs. Of these costs, 57% are attributed to low- and middle-income countries.

Prevention

Many of the causes that lead to hearing loss can be avoided through public health strategies and clinical interventions implemented across the life course.

Prevention of hearing loss is essential throughout the life course, from prenatal and perinatal periods to older age. In children, nearly 60% of hearing loss is due to avoidable causes that can be prevented through implementation of public health measures. Likewise, most common causes of hearing loss in adults, such as exposure to loud sounds and ototoxic medicines, are preventable.

Effective strategies for reducing hearing loss at different stages of the life course include:

• immunization;
• good maternal and childcare practices;
• genetic counselling;
• identification and management of common ear conditions;
• occupational hearing conservation programmes for noise and chemical exposure;
• safe listening strategies for the reduction of exposure to loud sounds in recreational settings; and
• rational use of medicines to prevent ototoxic hearing loss.

Identification and management

Early identification of hearing loss and ear diseases is key to effective management.

This requires systematic screening for detection of hearing loss and related ear diseases in those who are most at risk. This includes:

• newborn babies and infants
• pre-school and school-age children
• people exposed to noise or chemicals at work
• people receiving ototoxic medicines
• older adults.

Once hearing loss is identified, it is essential that it is addressed as early as possible and in an appropriate manner, to mitigate any adverse impact.

Rehabilitation for hearing loss

Rehabilitation helps people with hearing loss to function at their optimum, which means they can be as independent as possible in everyday activities. Specifically, rehabilitation helps them to participate in education, work, recreation and meaningful roles, e.g. in their families or communities–throughout their lives. Interventions for rehabilitation for people with hearing loss include:

• the provision of, and training in the use of, hearing technologies (e.g. hearing aids, cochlear implants and middle ear implants);
• speech and language therapy to enhance perceptive skills and develop communication and linguistic abilities; training in the use of sign language and other means of sensory substitution (e.g. speech reading, use of print on palm, Tadoma, signed communication);
• the provision of hearing assistive technology, and services (e.g. frequency modulation and loop systems, alerting devices, telecommunication devices, captioning services and sign language interpretation); and
• counselling, training and support to enhance engagement in education, work and community life.

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