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Probes and Tips - April 2009 - Learning Which Parts of the Hearing System are Screened with Otoacoustic Emissions (OAE) and Tympanometry

the National Center for Hearing Assessment and Mangement

This newsletter provides TIPS to enhance your OAE screening and follow-up practices and PROBES about current activities so we can learn from one another's successes and challenges. Check out our website for more helpful resources: www.infanthearing.org/earlychildhood

April, 2009 issue

Tip of the Month 

Learning Which Parts of the Hearing System are Screened with Otoacoustic Emissions (OAE) and Tympanometry


Some screeners incorrectly tell parents that the OAE screening is testing the child's eardrum (tympanic membrane).  Others assume that OAE screening is the same procedure that health care providers perform to test whether a child's middle ear is functioning properly (tympanometry).  Although screeners don't need to have a detailed understanding of how the auditory system works, it is important to have a basic understanding of the parts of the ear and the difference between OAE screening and tympanometry. 

The three main parts of the ear are the outer ear, the middle ear, and the inner ear (cochlea). When the hearing system is functioning as it should, sounds enter through ear canal, causing the eardrum (tympanic membrane) to vibrate, which in turn moves three small bones in the middle ear (hammer, anvil, stirrup).  This movement stimulates fluid movement in the inner ear (cochlea) and the sound signal is transmitted through a nerve to the brain. At the same time, the inner ear emits small signals, called  "otoacoustic emissions" that move back through the middle ear and into the ear canal.  These emissions are picked up and analyzed by the OAE screening equipment. 

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If the cochlea is not functioning properly, and the screening equipment does not pick up a strong OAE signal, the child will not pass the screening and may have a permanent hearing loss.   Alternately, if blockage in the outer or middle ear is preventing the sound from getting to the inner ear, or the emissions from coming back through the canal and reaching the OAE probe, the child will not pass the OAE screening.

Health care providers do not typically have OAE equipment in their offices or clinics.  When a child is suspected of having a middle ear infection, or when a child does not pass the OAE screening, a health care provider can often perform tympanometry which measures the movement of the eardrum.  This helps the provider know whether there is fluid/infection in the middle ear.  Tympanometry cannot test the functioning of the inner ear.  Children who pass tympanometry, but do not pass the OAE screening, must be referred to a pediatric audiologist for a comprehensive assessment.

Although OAE screening will help us identify most of the children who need middle ear consultation from a health care provider or a full audiological evaluation from a pediatric audiologist, it is also important to respond to parent concerns or other indications that a child is not developing speech and language normally.  Children who have language delays should be evaluated by a pediatric audiologist even if they pass the OAE screening.
Probe of the Month

Did you know that the functioning of the inner ear is screened with Otoacoustic Emissions technology and the middle ear is screened with tympanometry?

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