Hearing well requires many parts working together in harmony.
Our hearing system is divided into three sections that we refer to as the external ear, the middle ear and the inner ear. Each section plays an important role in how sound waves are channeled from the outside world and converted into signals our brain can interpret as meaningful information.
Journey through the ear
Parts of the human ear.
The outer ear is comprised of the pinna and the ear canal. The pinna acts like a dish that collects sound. The ear canal acts like a funnel to direct sound to the ear drum. Sound is simply a vibration of air molecules, so these sound waves strike the ear drum and cause it to vibrate. Sound is then sent to the middle ear. Attached to the ear drum are the three smallest bones in the body – the hammer, anvil, and stirrup. These bones move and mechanically conduct sound to the inner ear.
Within the inner ear is a snail shell-like chamber we call the cochlea. Fluid washes over tiny hair cells in the cochlea in response to the movement of sound. Each one of these tiny hair cells is tuned to a different pitch like the keys on a piano. The sound is then converted to electrical impulses and sent to the brain where we interpret meaning.
If there is an issue with any one of the parts of the hearing systems, the result may be a hearing loss.
If a problem occurs within the outer or middle ear, the result is a Conductive hearing loss. Conductive hearing losses comprise only 5% of all hearing losses. They can be caused by trauma, disease, ear infections, or wax, to name a few. Sometimes, a Conductive hearing loss can be corrected by surgery or medication.
Sensorineural hearing loss occurs within the inner ear. 95% of all hearing loss cases are Sensorineural hearing losses. The aging process, noise exposure, viruses and infections are all causes of Sensorineural hearing losses. Because this type of hearing loss cannot be treated medically, the solution is typically a hearing aid.
Measuring hearing
An audiogram is used to chart your hearing measurement.
To determine whether or not you have a hearing loss and, if so, what type you have, your hearing healthcare professional will perform a hearing test to measure your perception of sounds at different loudness levels for each pitch. You will be tested in the quiet of a sound booth with earphones by playing tones at various pitches from soft to loud to determine at what point you can first detect each sound. We refer to these points as your threshold of hearing. The results of your hearing test will then be recorded on a graph we call an audiogram.
On the top of the audiogram are the pitches that are important for understanding speech. It begins with low pitched sounds on the left hand side and as the numbers increase, so does the pitch. On the side of your audiogram, you will see the loudness level. As the numbers increase, so does the volume of the test signal. The further down the symbols are on the graph, the louder the sound had to be turned up before you could just barely hear it. In other words, the lower the symbols are on the graph, the more hearing loss you have at that pitch.
Your hearing healthcare professional will discuss your audiogram with you, along with your lifestyle, expectations, and preferences to determine what course of treatment is necessary and if a hearing aid is appropriate for you.
