Describing Hearing Loss (page 2)
"Your child has a hearing loss." Those words may cause any number of reactions, ranging from shock and disbelief, to denial or anger, to sadness and confusion. Many images appear in the minds of parents when they learn their child has a hearing impairment. Concern about their child's future and education contribute to the stress with which family members must cope.
To understand hearing lose, it is first necessary to understand how a person hears. Hearing begins when sound enters the external part of the ear and travels into the ear canal. Sound then causes the eardrum to vibrate. This part of the ear is called the outer ear. On the other side of the eardrum is a small space called the middle ear. Three tiny bones begin to move in a chain reaction when the eardrum vibrates. These bones connect with the third part of the ear, the inner ear. The inner ear includes the cochlea and is where nerve impulses are stimulated. Sound is then carried by these nerves to the brain. Hearing loss may be caused when the transmission of a sound is disrupted anywhere within this system.
The three different types of hearing loss are conductive, sensorineural, and mixed, (Boone. 1987). Hearing professionals, such as audiologists, are trained to determine the type of hearing loss of an individual. When sound cannot gee through the outer ear or the middle ear, it is considered a conductive hearing loss. When the transmission of sound is disrupted somewhere in the inner ear, such as in the cochlea or auditory nerve, it is called a sensorineural hearing loss. When there is a conductive and sensorineural problem it is called a mixed loss. Hearing loss does not automatically mean deaf. There are varying degrees of hearing loss. In addition, both ears may have a similar loss or one ear may be more affected.
Audiologists measure the amount of hearing loss a person experiences by looking at two dimensions of sound: loudness, measured in decibels (dB), and pitch, measured in Hertz (Hz). Sounds range from high to low pitches. These two dimensions are plotted on a chart called an audiogram. Audiologists describe a hearing loss as mild, moderate, severe, or profound (Pappas, 1985). Table 9.1 provides a summary of the generally accepted degrees of hearing loss and their descriptive labels. Table 9.3 shows the decibel levels of several common sounds found in the environment.
Loudness and pitch are two important factors in sound. Clarity, another important factor, is harder to identify. Sounds are sometimes distorted with a hearing loss, resulting in a loss of clarity, causing one sound to be mistaken for another sound. For example, the word share may sound like chair. When children experience frequent distortions in everyday conversation, the hearing loss could adversely affect their daily functioning. To determine whether a child has a hearing loss, several different types of hearing tests can be conducted (Pappas, 1985).
Degrees of Hearing Loss
|0-15 dB||Normal hearing|
|15-30 dB||Mild hearing loss|
|30-60 dB||Moderate hearing loss|
|60-90 dB||Severe hearing loss|
|90+ dB||Profound hearing loss|
Decibel Levels of Some Common Sounds
|30||Soft whisper (10-25)|
|50||Normal conversation (25-50), Licing room sounds|
|60||Crying baby, Air conditioner|
|80||Ringing telephone, Barking dog|
|90||Lawn mower, Hair blow dryer|
|100||Electric razor, Snowmobile|
|110||Power saw, Jet engine, Helicopter|
|140||Jet engine (close proximity)|
© ______ 1997, Merrill, an imprint of Pearson Education Inc. Used by permission. All rights reserved. The reproduction, duplication, or distribution of this material by any means including but not limited to email and blogs is strictly prohibited without the explicit permission of the publisher.
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