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, moderately severe, 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 can benefit from cochlear implants. Some of them 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 hearing loss
• sudden sensorineural hearing loss.

Factors across the life span

• cerumen impaction (impacted ear wax)
• trauma to the ear or head
• loud noise/loud sounds exposure
• 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:

• limitations in communication and speech
• adversely affected cognition
• social isolation, loneliness and stigma
• impact on society and economy
• effects on years lived with disability (YDLs) and disability adjusted life years (DALYs)
• limitations in access to education and employment.

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
• 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.

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