In order to understand hearing loss, it is important to understand how the ear works.
The ear consists of three main parts:
- Outer Ear
- Middle Ear
- Inner Ear
The Outer Ear
The auricle (pinna) is the visible portion of the outer ear. It collects sound waves and channels them into the external auditory meatus (ear canal) where the sound is amplified. The sound waves then travel toward a flexible, oval membrane at the end of the external auditory meatus called the tympanic membrane (eardrum). The tympanic membrane begins to vibrate.
The Middle Ear
The vibrations from the eardrum set the ossicles into motion. The ossicles are three tiny bones (smallest in the human body): malleus (hammer), incus (anvil) and stapes (stirrup) which further amplify the sound.
The stapes attaches to the oval window that connects the middle ear to the inner ear. The Eustachian tube, which opens into the middle ear, is responsible for equalizing the pressure between the air outside the ear to that within the middle ear.
The Inner Ear
The sound waves enter the inner ear and then into the cochlea, a snail shaped organ. The cochlea is filled with a fluid that moves in response to the vibrations from the oval window. As the fluid moves, 25,000 nerve endings are set into motion. These nerve endings transform the vibrations into electrical impulses that then travel along the VIII cranial nerve (auditory nerve) to the brain.
The brain then interprets these signals and this is how we hear. The inner ear also contains the vestibular organ that is responsible for balance.
Types of Hearing Loss
Hearing loss can develop at any age and may be caused by many different factors.
A hearing loss can be categorized in 3 different ways:
Sensorineural Hearing Loss
This type of hearing loss occurs when the inner ear or the actual hearing nerve itself becomes damaged. This loss generally occurs when some of the hair cells within the cochlea are damaged.
Sensorineural loss is the most common type of hearing loss. It can be a result of aging, exposure to loud noise, injury, disease, oto-toxic drugs or an inherited condition. This type of hearing loss is typically not medically or surgically treatable, however many people with this type of loss find that hearing aids can be beneficial.
Conductive Hearing Loss
Conductive hearing loss occurs in the outer or middle ear where sound waves are not able to carry all the way through to the inner ear. Sound may be blocked by earwax or a foreign object located in the ear canal, the middle ear space may be impacted by fluid and infection or a bone abnormality, or the eardrum may have been injured.
In some people, conductive hearing loss may be a temporary loss, which can be reversed through medical or surgical intervention. Conductive hearing loss is most common in children who may have recurrent ear infections or insert foreign objects into the ear canal.
Mixed Hearing Loss
Mixed hearing loss occurs when there is a combination of both sensorineural and conductive hearing loss. People may have a sensorineural hearing loss and then develop a conductive component in addition to their original loss.
A hearing testing, or audiogram is critical for discovering exactly what type of hearing loss you have, and will help determine the hearing care solution that is right for you. Hearing aids are available in many sizes/styles and technologies, as are many alternatives to hearing aids.