HEARING LOSS VS DEAFNESS
A person who is not able to hear as well as someone with normal hearing – hearing thresholds of 25 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. People with more significant hearing losses may benefit from cochlear implants.
'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
The causes of hearing loss and deafness can be congenital or acquired.
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 new-born infant.
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.
- Wax or foreign bodies blocking the ear canal.
Among children, chronic otitis media is a common cause of hearing loss.
IMPACT OF HEARING LOSS
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 and ear diseases such as otitis media can have a significantly adverse effect on the academic performance of children. They often have increased rates of grade failure and greater need for education assistance. Access to suitable accommodations is important for optimal learning experiences but are not always available.
Social and emotional impact
Exclusion from communication can have a significant impact on everyday life, causing feelings of loneliness, isolation, and frustration, particularly among older people with hearing loss.
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%)
Some simple strategies for prevention of hearing loss include:
- Immunising children against childhood diseases, including measles, meningitis, rubella, and mumps.
- Immunising 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.
IDENTIFICATION AND MANAGEMENT
Early detection and intervention are crucial to minimising the impact of hearing loss on a child’s development and educational achievements. In infants and young children with hearing loss, early identification and management through infant hearing screening programmes can improve the linguistic and educational outcomes for the child. Children with deafness should be given the opportunity to learn sign language along with their families.
Pre-school, school, and occupational screening for ear diseases and hearing loss is an effective tool for early identification and management of hearing loss.
People with hearing loss can benefit from the use of hearing devices, such as hearing aids, cochlear implants, and other assistive devices. They may also benefit from speech therapy, aural rehabilitation, and other related services. However, global production of hearing aids meets less than 10% of global need and less than 3% of developing countries’ needs. The lack of availability of services for fitting and maintaining these devices, and the lack of batteries are also barriers in many low-income settings.