Types of Hearing Loss
Hearing loss can be caused by a number of reasons such as illness (middle ear infection), injury (head trauma), noise exposure (workplace) or heredity. In addition to hearing loss being a natural part of aging, a growing number of individuals are experiencing hearing loss due to prolonged exposure to high intensity noise or repetitive noises (such as very loud music, machinery, gunfire and motorcycles). The latest statistics indicate that 1 out of 7 individuals does not have full hearing and 1 out of 10 hears so poorly that they would benefit from hearing aids. By the time we reach our 20’s, we’ve already lost the ability to perceive sound as we did as children and this gradually progresses throughout our lives. By the time we reach our 40’s or 50’s, a significant hearing loss has begun to occur.
Conductive Hearing Loss – This type of hearing loss results when there is an issue with the conduction of sound from the outer ear (the part that you see) to the inner ear (the part where the nerve is located). Issues arise when there is wax build-up, ear infections, trauma to the ear, or any other problem eardrum or bones that conduct sound through the middle ear. Individuals with this type of hearing loss have an issue with volume rather than an understanding ability.
Sensorineural Hearing Loss – This type of hearing loss involves the deterioration of the inner ear or the inner ear or the hearing nerve. As people age, noise-exposure, some cancer treatments, illness and other degenerative processes can contribute to this type of hearing loss. This type of loss can sometimes impair the ability to understand and can cause those with the loss to be sensitive to loud sounds.
Mixed Hearing Loss – This type of hearing loss contains some conductive elements and some sensorineural elements.
Degrees of Hearing Loss
Mild Hearing Loss – Individuals are unable to detect soft sounds and they experience difficulty with understanding speech clearly in noisy environments.
Moderate Hearing Loss – Individuals are unable to detect soft and moderately loud sounds and they experience difficulty with understanding speech particularly with background noise.
Severe Hearing Loss – Individuals find that some loud sounds are audible and communication without a hearing instrument is difficult.
Profound Hearing Loss – Individuals find that some extremely loud sounds are audible but communication without a hearing instrument is impossible.
Functions of the Ear
Your ear is a very complex organ that is comprised of three parts: the outer ear, the middle ear and the inner ear. We “hear” as a result of the auditory nerve located within the inner ear, transmitting information to the brain for processing.
The Outer Ear – The outer ear contains the “auricle”, the “auditory canal” and the “eardrum”. The outer ear funnels sounds from the surrounding environment into the hearing system. Then, the auricle helps to gather the sound waves and the auditory canal directs these waves to the eardrum.
The Middle Ear – The middle ear which is an air-filled cavity, contains the smallest bones in the human body (the “malleus”, the “incus” and the “stapes”. These bones are connected to the eardrum on one side and on the other side, to a thin membrane-covered opening which is on the wall of the inner ear. In addition, the middle ear is connected to the throat which keeps the air pressure in the middle ear equal to that of the surrounding environment.
The Inner Ear – Within the inner ear, the auditory input is processed by the “cochlea”, while the information affecting balance is processed by the “semicircular canals”. The entire length of the fluid-filled cochlea are tiny hair cells. These hair cells become bent when fluid is displaced by sound waves which were passed on by the middle ear bones. This in turn triggers a chemical response which activates the corresponding nerve endings. From here, the message is transmitted to the area of the brain which is in charge of interpreting auditory input.
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