In order to understand your hearing loss it is important to understand our sense of hearing in general. As these pictures indicate sound waves traveling through the air are captured by the outer ear (pinna) and funneled through the external ear canal. At the end of the external ear canal the sound waves hit the eardrum (tympanic membrane) and it vibrates. These vibrations are relayed through the middle ear by three small bones (ossicles). The last ossicle, called the stapes, is connected to the cochlea. The cochlea is a fluid filled structure which houses the end of our auditory nerve. Vibrations from the ossicles set the cochlear fluid in motion which stimulates the sensitive auditory nerve endings. The auditory nerve carries the signal to the brain where meaning is assigned to the signal.
There are two primary types of hearing loss…conductive and sensorineural. There is also a combination of these two types which is know as a mixed hearing loss. We will discuss all three.
Conductive hearing loss - this type of hearing loss occurs when the outer or middle ear are physically blocked, damaged or malformed. This blockage, damage or malformation prevents the sound from being transmitted to the cochlea.
Conductive hearing losses include wax (cerumen) blocking the external canal, a hole in the eardrum (perforated tympanic membrane), middle ear infections or problems with the bones (ossicles) of the middle ear. The ossicles may be damaged by head trauma, grow stiff from disease or be malformed at birth.
Any of these conditions may result in hearing loss simply by blocking the sound waves and preventing, or at least diminishing the strength of, the signal reaching the auditory nerve endings housed in the cochlea.
The good news is that most conductive hearing losses can be treated medically. If you are diagnosed with a conductive hearing loss you will be referred to your primary care physician or an otolaryngologist (ear, nose & throat specialist) for treatment.
Sensorineural hearing loss - this type of hearing loss (often referred to as a nerve loss) occurs whenever there is a problem with the auditory nerve. The nerve endings are damaged or worn as a result of age, illness, or noise exposure. The auditory nerve is simply not capable of receiving and transmitting complete, clear information to the brain.
Typically a sensorineural hearing loss cannot be treated medically. Depending on the degree of your hearing loss, hearing aids may be recommended. Only you can determine if your hearing loss is aggravating enough to you or your family to warrant hearing aids.
Mixed hearing loss - a mixed hearing loss is simply a combination of conductive and sensorineural hearing losses.
During
your hearing test you will be asked to listen for a series of beeping
tones through a pair of headphones. You respond by pressing a button,
raising your hand or by simply saying that you hear the tone. You will
also be asked to repeat several words at different volume levels. There
may also be a need for a pressure test to determine if there is any fluid
or pressure behind you eardrum.
These tests are quick, simple and painless but it will give the audiologist all the information needed to determine your type and degree of hearing loss for each ear. Your results will be explained to you along with any recommendations for follow up care or referral for medical treatment.
There are additional test procedures for children which are tailored to the individual child’s age and abilities
Hearing Aids
If hearing aids are recommended there are several things you should consider before making any decisions.
1) The size of the hearing aids.
As you probably know hearing aids come in several different sizes. Personal preference, finger and hand dexterity, the type and degree of your hearing loss as well as cost should be considered when making your decision about which size hearing aids to try.
Personal preference - This one doesn’t really need much explanation except to say that you should select the size of hearing aids that you are comfortable with and will use. Don’t settle for hearing aids that you don’t like. They are much more likely to end up in a drawer instead of your ears if you don’t like the way the hearing aids look or fit.
Finger and hand dexterity - This one is important. Remember hearing aids, their controls and batteries are very small. Arthritis, finger numbness and limited range of motion may effect how well you can insert your aids, operate the controls and change the batteries. Ask your audiologist to show you demo aids and batteries to get an idea of the size of the hearing aids that you are considering.
Type and degree of your hearing loss - Your audiologist will counsel you regarding which aids offer the best amplification for your hearing loss. Certain circuits may not be available in all sizes of hearing aids. Other considerations including venting and reserve gain should be explained by your audiologist.
Cost - Simply put…the smaller the hearing aids…the bigger the price tag.
Completely-in-the-Canal hearing aids ( CIC )
In-the-Canal hearing aids ( ITC )
In-the-Ear hearing aids ( ITE )
Behind-the-Ear hearing aids ( BTE )
2) Circuitry
Regardless of what size hearing aid you select, it is the circuitry on
the inside that improves your hearing. Each manufacturer has literally
dozens of circuits available but they can be summarized into three categories:
Digital Circuitry - the most advanced circuitry available. Digital hearing aids are very flexible and appropriate for most hearing losses. Digital circuits can be programmed with multiple frequency responses. This feature along with multiple microphones and speech analysis and processing features make digital circuits very flexible and beneficial in many different environments.
Digital circuits can be reprogrammed as needed to suit your preferences or changes in your hearing which is important for both short term and long term fitting success
Programmable Circuitry - advanced circuitry. Programmable hearing aids are relatively flexible and can usually be programmed with multiple frequency responses like the digital circuits. They typically do not have quite the same degree of flexibility or options as the digital circuits. Programmable circuits offer quality amplification and can be fine tuned to your personal preferences as well as allow for future adjustments.
Conventional Circuitry - old technology with limited flexibility. Conventional
hearing aids offer the fewest controls and adjustments. This may limit
the “fine tuning” that can be done in order to fit your hearing
loss in both the short term and long term. Offers basic and economical
amplification.
