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JANUARY-FEBRUARY , 2022 | THE HEALTH
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HEARING LOSS occurs when the ability to hear is impaired compared to someone with normal hearing . Humans can detect sounds from a range of frequency from 20Hz to 20kHz , while its loudness is measured in decibel ( dB ).
A normal hearing for each frequency is defined as having a hearing threshold of 25dB or better . Some level of hearing loss is said to occur below this threshold .
Hearing loss can be mild ( 26- 40dB ), moderate ( 41dB-55dB ), moderately severe ( 56-70dB ), severe ( 71-90dB ) and profound (> 91dB ). Deafness in an ear usually refers to at least a profound or total hearing loss .
Our ear is divided into three parts which are outer , middle and inner ear .
The outer and middle ear are responsible for conducting and amplifying the sound from the environment , while the inner ear is responsible for converting mechanical sound energy into electrical impulses to be sent for processing in the auditory cortex of the brain .
Hearing loss can occur when there is disruption in the conduction of sound due to the outer and middle ear problems , which results in Conductive type hearing loss . Pathology in the inner ear will result in a Sensorineural type hearing loss . A combination of both Conductive and Sensorineural type hearing loss is referred to as Mixed hearing loss .
The most common cause of Conductive hearing loss is impacted ear wax in the outer ear . Other common conditions that cause conductive hearing loss include :
Outer ear : otitis externa ( swollen ear canal ), foreign body or congenital causes such as ear canal atresia ( failure of normal external ear development ).
Middle ear : middle ear effusion / otitis media ( fluid in the middle ear ), ossicular dislocation from trauma and otosclerosis
For Sensorineural hearing loss , the most common cause is presbyacusis ( degeneration from ageing ). In adults , it can also happen from damage to the inner ear because of prolonged exposure to noise hazards which can be work-related , head injury or ototoxicity ( drug-induced ).
Sensorineural hearing loss can also occur in a child . In such cases , it could either be congenital ( from birth ) or developmental ( after birth ). Conditions that can cause Sensorineural hearing loss in a child include prematurity , certain syndromes with craniofacial anomalies , meningitis and hyperbilirubinaemia ( jaundice ).
The presentation of a person with hearing loss depends on age . A child with hearing loss may present with speech delay or other learning disabilities , while an adult may have difficulty communicating while also speaking inappropriately loud .
Having a hearing impairment is also shown to affect an individual ’ s self-confidence . This would lead to social withdrawal and depression . Tinnitus ( ringing in the ear ) is also a common symptom in patients with hearing loss .
While newborn hearing screening is commonly done before discharge , parents need to be always vigilant if they suspect hearing loss in their child . This is because speech-language development is crucial in the first two years of a child ’ s life .
The earlier it is recognised , the earlier intervention could be instituted , the better the chances of normal development for the child . This is mainly for a child with bilateral ( both ear ) deafness and may require a cochlear implant .
One should also be aware that hearing
Never ignore hearing loss
We should be aware that hearing loss could be only a part of a symptom of a more sinister underlying health diagnosis
BY DR JOHNSON NG WEI SIANG
loss could be only a symptom of a more sinister underlying health diagnosis . A unilateral ( one-sided ) ear block sensation that does not resolve over a week warrants further assessment . It could also be an early symptom of NPC ( nasopharyngeal carcinoma ) due to the mass in the nasopharynx obstructing the Eustachian tube opening .
Sinusitis can also cause a similar hearing loss although it is usually transient , while underlying adenoid hypertrophy may cause a child with persistent middle ear effusion .
To diagnose hearing loss in an adult , a pure tone audiogram is commonly performed to assess the level and severity of the hearing loss . A BSER ( Brainstem Evoked Response ) to detect the brain wave activity to a given sound stimulus is preferred for a younger child .
Management of hearing loss depends on the cause . Clearing of impacted ear wax may resolve the hearing loss .
Middle ear effusion may be treated medically or if it persist surgically with myringotomy and grommet insertion . Hearing loss that lasts or of sensorineural type may require a hearing aid if the hearing loss is indeed impairing quality of life . Types of hearing aids depend on an individual ’ s level of hearing loss , preference and dexterity in handling the minor type hearing aid .
For a child with bilateral profound hearing loss , a cochlear implant early in a child ’ s speech-language development would be crucial for the best outcome .
Optimal management of hearing loss also aims to restore binaural hearing . Binaural hearing ( hearing with both ears ) has the advantage of localising the direction of a sound . Hence , a person with single-sided hearing loss may have difficulties determining the direction of sound and reduced sound clarity .
Non-medical treatment of hearing loss aims at prevention and slow its progress . Individuals should practice good ear care in avoiding prolonged exposure to loud noises , which can damage the inner ear ’ s hair cells .
Earplugs should be used if noise hazard in the work environment cannot be avoided . Consumption of certain vitamin supplements may also help slow the progression of nerve degeneration . — The Health
Dr Johnson Ng Wei Siang is Consultant ENT / Head & Neck Surgeon at Sri Kota Specialist Medical Centre , Klang .