Hearing Test

Why Would I Need a Hearing Test?

Hearing Test:  Outer Ear

The outer ear consists of the pinna. The pinna is responsible for funneling sound down to your ear canal and bringing sound to your tympanic membrane. This is what is often called the eardrum. The sound coming into the ear canal is called acoustic sound because the sound comes from air molecules moving from a person talking, across the span of space, to your ear canal. The air molecules meet the tympanic membrane where the sound is transmitted behind the tympanic membrane as mechanical energy through the three small ear bones, called the malleus, incus and stapes. The small ear bones move because the largest of the three ear bones is attached to the tympanic membrane. 

Things that can hinder your hearing in the outer ear are: earwax, ear infections which make the tympanic membrane tight and more difficult for the air molecules to move and create sound. Ear wax or cerumen is the most common difficulty in the outer ear canal. One interesting fact is that if you have a full blockage of wax in the ear, it can create up to a 40% loss of hearing that is correctable simply in removing the wax and allowing the sound waves to reach the tympanic membrane. 

Hearing Test:  Middle Ear 

Once the sound reaches the tympanic membrane, the sound is changed into mechanical energy through the three small ear bones, called the malleus, incus and stapes. The small ear bones move because the largest of the three ear bones is attached to the tympanic membrane. The movement of the tympanic membrane moves down the chain of bones until it touches the oval window that is attached to the smallest bone in the entire body, the stapes. The pressure of the sound waves on the oval window is some 20 times higher than on the eardrum. The pressure is increased due to the difference in size between the relatively large surface of the eardrum and the smaller surface of the oval window. Can you imagine the sound increasing 20 times in that small space of the middle ear in order to allow you to both hear and understand words? This is how amazing the ear is for listening. 

When you have difficulty with the middle ear system, this can be related to ear infections, perforated tympanic membranes, calcified or hardened middle ear bones, ossicular discontinuity (ossicles not touching one another), cholesteotoma, history of ear surgery or ear infections as a child and other middle ear diseases. When you have a middle ear difficulty, the mechanical portion of the transmission of sound is inhibited and this causes you to need the sound to be louder. The louder sound is needed in order to have the middle ear bones and tympanic membrane to oval window transmission work. 

A wonderful test for this portion of the ear is called a Tympanogram. The tympanogram determines if the tympanic membrane is functioning well and if there is any perforation or middle ear pressure that must be addressed. 

Hearing Test:  Auditory Pathways 

Once the sound passes through the middle ear it stimulates the oval window which is the membrane which allows the sound to move from mechanical to hydraulic transmission in the cochlea. 

If you were to take the cochlea, and straighten it out of the coil that it is in, then you would find the cochlea is like a piano keyboard. The long line of the cochlea, stretched out, reveals that the cochlea has high frequency hair cells at the base of the cochlea and low frequency hair cells at the apex of the cochlea. When sound crosses over the hair cells, it does so much like an ocean wave that you can see visibly. The wave moves over the miniscule hair cells and causes them to be “excited” or to move up and down. This up and down movement moves to a neural network where the sound moves up various portions of the brain where it finally is processed by the temporal lobe. When the sound moves along correctly, in a normal hearing individual, the temporal lobe receives information that correlates to words and speech. When the individual has hearing loss, the temporal lobe receives sound with “gaps” of sound wherein the word is not transmitted properly and therefore can’t be perceived properly by the temporal lobe. 

This causes the misunderstanding of words. For example, in a normal hearing individual the words “baseball” would be transmitted correctly through the ear and up to the temporal lobe where the word would properly be heard as “baseball.”  When there are gaps, there are portions of the word that are not transmitted properly and therefore the temporal lobe receives only a portion of the word. In this case, the individual could hear “b b ll.”  When this happens, the individual has to fill in the gaps of what they can’t hear and try to make sense of words. If you add in background noise or complex noise environments like crowds, this becomes increasingly harder. The end result is that the individual begins to retreat from various aspects of their life and begins to become isolated and depressed. 

If you struggle to hear the television, or understand conversations, even in restaurants or other or other noisy environments, it's time to see an audiologist.  We're here to help.  

A hearing test can provide the answers you need to help you hear at your very best.  Schedule your appointment for a comprehensive hearing evaluation and find out how you can better communicate and connect with the people in your life.