How do we hear?
In humans, hearing is performed primarily by the auditory system. This system is made up of the Outer Ear, Middle Ear and Inner Ear.
The Outer Ear is comprised of folds of cartilage surrounding the ‘pinna’ (ear canal). Sound waves are reflected and attenuated when they come in contact with the pinna. These sound waves then enter the auditory canal which amplifies the sounds before they enter the middle ear.
The Middle Ear contains the tympanic membrane (eardrum) along with a series of delicate bones, the malleus, incus and stapes. These bones assist in converting the lower-pressure sound vibrations into higher-pressure vibrations and direct these towards another smaller membrane. The middle ear contains the sound information in wave form, it is converted into nerve impulses in the cochlea.
The Inner Ear consists of the cochlea and several non-auditory structures. The cochlea is a spiral-shaped cavity. It contains the Organ of Corti, the sensory organ of hearing, which is distributed along the partition separating fluid chambers in the cochlea.
What causes hearing loss?
Hearing loss can be caused by many different causes, some of these causes can be successfully treated with medicine or surgery.
Conductive Hearing Loss:
When hearing loss is caused by issues with the ear canal, ear drum or middle ear, this is known as Conductive Hearing Loss.
- Malformation of outer ear, ear canal, or middle ear structures
- Fluid in the middle ear from colds
- Ear infection (otitis media – an infection of the middle ear in which an accumulation of fluid may interfere with the movement of the eardrum and ossicles
- Poor Eustachian tube function
- Perforated eardrum
- Benign tumors
- Impacted earwax
- Infection in the ear canal
- Foreign body in the ear
Sensorineural Hearing Loss
When hearing loss is due to problems of the inner ear, also known as nerve-related hearing loss.
- Exposure to loud noise
- Head trauma
- Virus or disease
- Autoimmune inner ear disease
- Hearing loss that runs in the family
- Aging (presbycusis)
- Malformation of the inner ear
- Meniere’s Disease
- Otosclerosis – a hereditary disorder in which a bony growth forms around a small bone in the middle ear, preventing it from vibrating when stimulated by sound.