By Dr Ananya Mandal, MD
Hearing loss is most commonly caused due to two major causes – age related hearing loss and hearing loss due to exposure to loud noises of acoustic trauma. There are numerous other causes that include disease and drugs that may damage the functioning of the ears and lead to hearing loss.
Causes of hearing loss include age related hearing loss, acoustic trauma and so forth. 1-5
Age related hearing loss
This also called presbyacusis and is the largest single cause of hearing impairment. Hearing loss begins normally between ages of 30 and 40. This increases with age until by 80 most people have significant hearing impairment.
Presbyacusis occurs when the sensitive hair cells inside the cochlea gradually become damaged or die.
Common manifestations initially are inability to hear high-frequency sounds, such as female or children’s voices and inability to hear consonants, such as the letters s, t, k, p and f. This makes understanding conversations difficult especially with a background noise.
Hearing loss due to acoustic trauma
Ear damage may be caused due to exposure to loud noises over long periods of time. This repeated exposure to noise causes damage to the delicate inner structure of the ear. The hair cells within the cochlea may be inflamed.
Acoustic trauma and the extent of damage depend on the length of time and the loudness of the noise the person is exposed to. People who work in noisy environment and those who listen to music at a high volume through headphones are at a greater risk.
Hearing loss due to a perforated ear drum
This occurs due to injury or infection of the ear. In children an acute ear infection (acute otitis media) may lead to formation of pus within the middle ear. This may bulge out through the ear drum and the membrane may be perforated. Injury with sharp objects may also cause ear drum to perforate. This leads to a conductive hearing loss.
Hearing loss due to ear wax
Ear wax may get impacted within the ear canal and cause blockage of the ear canal leading to hearing loss. An obstruction of the ear canal with a foreign body like a bead or a small object may also act similarly. This leads to a conductive hearing loss.
Hearing loss due to Otosclerosis
This occurs when there is an abnormal growth of bone in the middle ear. This leads to lack of movement of the ossicles and the sound waves cannot be passed into the inner ear. This leads to a conductive hearing loss.
Genetic hearing loss
Sometimes hearing loss may run in families. This is more commonly of the sensorineural type.
Hearing loss due to viral infections
Viral infections like Mumps, measles and Rubella (German measles) may also cause hearing loss especially in children. This is more commonly of the sensorineural type. Brain infections like meningitis or encephalitis may also cause hearing loss.
Hearing loss due to Meniere’s disease
Meniere’s disease leads to a sensorineural hearing loss along with vertigo and tinnitus or ringing of the ears and feeling of pressure within the ears.
Hearing loss due to acoustic neuroma
A tumor of the auditory nerve that is non-cancerous may also lead to a sensorineural hearing loss.
Other causes of hearing loss
Multiple sclerosis and stroke are other causes of neurological hearing loss.
Head injury may also lead to hearing loss.
Children born with hearing impairments
Children with congenital conditions like Down syndrome, Usher syndrome, Treacher Collins syndrome, Crouzon syndrome, and Alport syndrome may be born with hearing impairment.
Hearing loss as a consequence of some drugs
Some drugs like those used in cancer and antibiotics like Aminoglycoside (gentamicin, Amikacin, Streptomycin etc.) may lead to nerve damage within the ear and hearing loss.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)