The Hearing Center
9095 Glacier Hwy. Suite #103
Juneau, AK 99801
Toll Free: 800-770-2359
How the ear works normally:
1. Sound is transmitted as sound waves from the environment. The sound waves are gathered by the outer ear and sent down the ear canal to the eardrum.
2. The sound waves cause the eardrum to vibrate, which sets the three tiny bones in the middle ear into motion.
3. The motion of the bones causes the fluid in the inner ear or cochlea to move.
4. The movement of the inner ear fluid causes the hair cells in the cochlea to bend. The hair cells change the movement into electrical pluses.
5. These electrical impluses are transmitted to the hearing (auditory) nerve and up to the brain, where they are interpreted as sound.
The Outer Ear
The part of the outer ear that we see is called the pinna, or auricle. The pinna provides a natural boost for sounds in the 2000 to 3000 Hz frequency range. The ear canal, also called the external auditory meatus, is the other important outer ear landmark. The ear canal is lined with only a few layers of skin and it is a highly vascularized area. This means that there is an abundant flow of blood to the ear canal.
The Middle Ear
The eardrum, or tympanic membrane (abbreviated TM) is the dividing line between the outer and middle ears. The ossicles are the three tiny bones of the middle ear that are fully developed at birth. They serve as a mechanical link between the tympanic membrane and the inner ear. The Eustachian tube is the middle ear’s air pressure equalizing system. The middle ear is encased in bone and does not communicate with the outside atmosphere except through the Eustachian tube.
The Inner Ear
The inner ear is a series of channels and chambers embedded deep within the temporal bone. The inner ear is called the cochlea. The cochlea transduces (changes from one form to another) the mechanical stimulus of sound, via the tympanic membrane and the ossicular chain, into a sequence of electrical discharges that is the language of the auditory nervous system.
There are different types of hearing loss, depending on which part of the hearing pathway is affected. A specialist will always try to localize where in the hearing pathway the problem lays, so as to be able to classify the hearing loss as belonging to one of the following groups. This is very important when determining the appropriate treatment.
Sensorineural hearing loss is the most common type of hearing loss. Most hearing aid wearers have sensorineural hearing loss. The most common causes of sensorineural hearing loss are age related changes and damage to the hearing due to noise exposure. Sensorineural hearing loss may also result from disturbance of inner ear circulation, increased inner fluid pressure or from disturbances within the hearing nerve. Sensorineural hearing loss may also be called "cochlear loss" and "inner ear loss" and is commonly called "nerve loss."
Many professionals once thought there was nothing that could be done for sensorineural hearing loss -- that is absolutely incorrect!!! There are many excellent options for patients with sensorineural hearing loss. People with sensorineural hearing loss typically report they can hear people speaking, but they can't understand what they're saying. People with sensorineural hearing loss also complain that "everyone mumbles." They also usually hear better in quiet places and may have difficulty understanding what is said over the telephone.
Conductive Hearing Loss is due to any condition that interferes with the transmission of sound through the outer and middle ear to the inner ear. This type of hearing loss can be successfully treated in many cases.
Some common causes of conductive hearing loss:
Modern techniques make it possible to treat and cure or at least improve the vast majority of cases involving problems with the outer or middle ear. Even if people with conductive hearing loss are not improved medically or surgically, they stand to benefit greatly from a hearing aid, because what they need most is amplification.
Frequently, a person experiences two or more types of hearing impairment, and this is called mixed hearing loss. This term is used only when both conductive and sensorineural hearing losses are present in the same ear. However, the emphasis is on the conductive hearing loss, because available therapy is so much more effective for this disorder.