Understanding Hearing Loss

The Basics of How We Hear

Sounds waves in the environment enter our ears to produce sound in two ways:

 

Air conduction:

• A sound wave enters the ear canal and hits the eardrum (tympanic membrane), causing a vibration.

• This vibration moves three tiny bones in the middle ear, known as the malleus, incus and stapes

• These bones push on the inner ear (cochlea), a fluid filled organ, causing pressure waves

• These pressure waves cause movement of microscopic sensory hairs, which stimulate the auditory nerve and send the sound to the brain

   

Bone conduction:

• A sound wave causes the bones of the skull to vibrate.

• This vibration is transmitted directly to the fluid-filled inner ear (cochlea), where the pressure waves are picked up by sensory hairs that are then transmitted to the brain.

 

Click here to watch a video on the basics of hearing.

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The Attributes of Hearing Loss

There are three attributes audiologists use to develop a complete picture of an individual's hearing loss: Type, Degree, and Configuration of hearing loss.

Type of Hearing Loss

 

There are three different types of hearing loss: Sensorineural, Conductive, or Mixed.  This categorization is determined based on which part of the auditory system is damaged. 

 

SENSORINEURAL HEARING LOSS:

This is the most common type of hearing loss and develops when there is damage to the inner ear (in the cochlea) or the nerves that connect the ear to the brain. Overall volume of sound is reduced, but more importantly, the ability to hear clearly and understand speech may also be impacted. At this time there is no medical or surgical correction for sensorineural hearing loss and it is considered a permanent type of hearing impairment. 

Click here to watch a video on sensorineural hearing loss.

 

CONDUCTIVE HEARING LOSS
This type of hearing loss occurs when sound waves do not travel through the ear correctly. Causes of conductive hearing loss can be things such as middle ear fluid, obstructions of the ear canal or abnormalities of the tiny bones of the middle ear. Overall sound volume is often reduced as a result of a conductive hearing loss. Some types of conductive hearing loss can be corrected surgically, which will be determined by your audiologist and otolaryngologist (ear, nose and throat physician).

Click here to watch a video on conductive hearing loss.

 

MIXED HEARING LOSS

This type of loss occurs when there is both a conductive hearing loss and sensorineural hearing loss. It is possible to have a conductive hearing loss and also have damage from factors such as age or exposure to loud sounds.

 

MIXED HEARING LOSS
This type of loss occurs when there is both a conductive hearing loss and sensorineural hearing loss. It is possible to have a conductive hearing loss and also have damage from factors such as age or exposure to loud sounds.

 

Degree of Hearing Loss

This refers to the severity of the hearing loss, or how loud sounds have to be in order to be heard, and is measured by the softest sound a person can hear [measured in a unit called decibels (dB)].

 

 

Configuration of Hearing Loss

This refers to what pitches/frequencies are affected by hearing loss. It is common to have some normal hearing at certain pitches, while having hearing loss at other pitches. Normal hearing in the low pitches with hearing loss in the high pitches is called a high frequency hearing loss. While normal hearing in the high pitches and hearing loss in the low pitches is called a low frequency hearing loss. When there is equal hearing loss across the pitches, it is called a flat hearing loss. 

When you get your hearing tested, you will receive a chart of your hearing, called an audiogram, which charts the frequencies where your hearing was tested and the volume that was needed in order for you to hear the sound. Your audiologist will review the results of your test with you and will give you a copy of your audiogram.

 

EXAMPLE OF AN AUDIOGRAM:

 

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For More Information

For a diagnosis of your hearing health and more information about causes of and treatments for hearing loss, find a hearing center near you to get a thorough diagnostic evaluation by one of Kaiser’s highly trained audiologists.