There are a variety of tests available that allow the Audiologist to detect hearing loss early and accurately. Typically in children under the age of 3 we rely on measurements that do not rely on the child to physically respond. Such tests are ABR (auditory brainstem response), or ASSR (auditory steady-state response), OAE (otoacoustic emissions), tympanometry and acoustic reflexes. Behavioral testing is also performed to “cross check” with the other tests. Behavioral audiometry is actually having the child respond to a stimulus either verbally or with gestures. This might involve raising his/her hand or pointing to objects or pictures or simply a turn of the head to a sound.
The ABR and ASSR are tests that involve presenting sound to the ear and electrically measuring the response to the sound as it travels through the brainstem . The ASSR differs from the ABR in that it can provide more specificity in regards to which sounds the child can or cannot hear. It can also test at louder or more intense levels which is important when determining cochlear implant candidacy.
OAE testing is a nice screening tool for presence or absence of moderate or greater hearing loss, but by itself does not provide enough information for a conclusive diagnosis. Tympanometry tests middle ear function (presence or absence of fluid or pressure in the middle ear) and acoustic reflex testing gives information regarding neural function of the hearing nerve and associated areas. The end goal is to have the child test with earphones, just like a little adult, but until the child is able to do so, our other battery of testing is necessary to identify hearing loss as early as possible.
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Robert Herring, Au.D.