Hearing loss frequently goes unnoticed, and because it happens gradually, many people are in denial about their hearing loss. They often stop communicating and withdraw from family, friends and social situations because they can’t understand what is being said.
Common signs of hearing loss
- Speaking louder than necessary in conversation
- Constantly asking for words to be repeated
- Straining to hear
- Misunderstanding conversations, especially in noisy situations
- Favouring one ear
- Thinking that people always mumble
- Turning the television or radio up louder than usual
- Having difficulty hearing on the telephone
- Withdrawing from social contact
- Ringing or buzzing in one or both ears
Causes and types of hearing loss
Hearing loss can be categorized by which part of the auditory system is affected. There are three basic types of hearing loss: sensorineural, conductive and mixed.
Sensorineural hearing loss
Sensorineural hearing loss occurs when there is damage to the inner ear (cochlea) or hearing nerve in the brain. Some causes of sensorineural hearing loss include:
- Aging – gradual age-related hearing loss is called presbycusis
- Excessive exposure to loud noise
- Viral or bacterial infections
- Certain medications
- Meniere's disease
- Acoustic neuroma – a benign tumour on the main nerve leading from the inner ear to the brain
- Hereditary factors
Conductive hearing loss
Conductive hearing loss occurs when sound is not conducted efficiently through the ear canal, ear drum or middle ear.
Some causes of conductive hearing loss include:
- Infection of the ear canal or middle ear
- Fluid in the middle ear
- Perforation or scarring of the eardrum
- Wax build-up
- Dislocation of the ossicles (three middle-ear bones)
- Foreign objects in the ear canal
- Otosclerosis – a hereditary disorder causing progressive deafness due to overgrowth of bone in the inner ear
- Unusual growths, tumors in the middle ear
Mixed hearing loss
Mixed hearing loss occurs when there is a combination of both sensorineural and conductive issues. This means that both the middle ear and inner ear are affected.
How the ear works
The outer part of the ear, the part that we see, is called the pinna and it channels sound into the ear canal. The ear canal directs the sound onto the eardrum, a paper-thin tissue which vibrates as sound waves hit it. The eardrum is attached to three tiny bones in the middle ear cavity. These bones pick up the vibrations from the eardrum and transfer them through the oval window into the fluid-filled cochlea of the inner ear. The vibrations create waves in the cochlea’s fluid. Hair cells in this fluid bend as the waves pass by and make nerve impulses that are carried to the brain for interpretation.
One other part of this complex structure is the eustachian tube which extends from the back of the throat to the middle ear. Generally speaking, it opens every time you yawn or swallow, ventilating the middle ear space. It equalizes the air pressure in the middle ear with the pressure around you. Problems with the eustachian tube usually result in conditions that require medical attention.