About Hearing Loss
How the Ear Works
The ear is composed of 3 parts: Outer Ear, Middle Ear and Inner Ear.
Outer Ear: Consists of the pinna and the ear canal. Sound is collected by the pinna and is funnelled down the ear canal to the eardrum.
Middle Ear: Consists of the eardrum and the middle ear space which holds the 3 little ear bones: malleus, incus and stapes. The middle ear ends where the stapes connects to the inner ear. The middle ear uses its three little bones to transfer energy from the vibrating eardrum into the fluid-filled cochlea.
Inner Ear: Begins at the opening of the cochlea which is connected to the middle ear by the stapes. The cochlea is a fluid-filled snail-shaped structure that houses about 20,000 sensory hair cells. These hair cells convert the movements of the fluid within the cochlea into electrochemical impulses that are sent by the hearing nerve. In normal hearing, the hair cells provide listeners with both volume and clarity.
Types of Hearing Loss
Hearing loss can occur when any part of the pathway of the ear does not work correctly.
Conductive hearing loss occurs when there is a problem in the Outer or Middle Ear. If sound cannot travel through the ear canal properly, or if the eardrum and middle ear bones cannot transfer the sound energy to the cochlea normally, a conductive hearing loss will occur. A conductive hearing loss will reduce the volume of sounds heard in the affected ear. Often times this type of hearing loss can be medically or surgically corrected. Some examples of conductive hearing loss include: impacted wax in the ear canal, a hole in the eardrum, ear infections and dislocated middle ear bones.
Sensorineural hearing loss occurs when the sensory hair cells in the cochlea are either damaged or not working properly. As a result, information cannot be correctly transmitted to the hearing nerve, resulting in reduced hearing and decreased clarity. A sensorineural hearing loss typically cannot be treated medically and is usually a permanent problem. Sometimes people can experience a sudden sensorineural hearing loss (SSHL) where a sensorineural hearing loss develops very rapidly. With SSHL, time is of the essence; patients should be assessed and treated by an ENT doctor within 72 hours.
Mixed hearing loss occurs when there is a combination of a conductive and sensorineural hearing loss at the same time.
Retrocochlear hearing loss refers to a hearing loss that result from problems with the hearing nerve.
Hearing aids are typically recommended to improve hearing in patients with conductive hearing losses (that cannot be corrected medically or surgically) and for patients with sensorineural hearing losses. Current hearing aid technology is significantly better than previous generations and has resulted in functional improvements for hearing impaired patients. However, when hearing loss deteriorates to the point where hearing aids provide limited to no benefit, then consideration for a cochlear implant may be appropriate.