Introduction

There is a big controversy about the best method of educating hearing impaired children of different hearing abilities. However, regardless of this controversy, there is an agreement that the earlier we test a baby's hearing, and act upon the results of the test, the better off is the baby.

If we know that the baby's hearing is perfectly normal, then the parents can devote their time and resources to other aspects of the child's development and education.

If the baby is found to be profoundly or totally deaf, the parents need time to recover from their emotional shock, learn about deafness, learn (and master!) visual communication methods (such as cued speech or Sign Langauge), prepare to advocate for their deaf child to ensure that the child gets the best education he/she can get from the school system, etc.

If the baby is found to be hard-of-hearing, hearing aids need to be fitted to the baby. The parents should prepare for raising an hard-of-hearing child, as outlined above (except perhaps for less reliance upon visual communication methods).

At any case, the methods described in the rest of this document address the need for the earliest possible diagnosis of hearing impairment in babies.

The ABR (Brainstem Evoked Response) Test

(Contributed by Chris deHahn at 17 Jan 1994.)

Disclaimer: I am not an audiologist.

The ABR (Brainstem Evoked Response) test, if performed correctly, is quite conclusive. The drawback is that it tests a narrow range of frequencies, although that range is the majority of the speech range. Later, when the child is capable of responding to environmental sounds, a wider range of frequencies can be tested in a sound booth. The drawback with this method in young children is to try and maintain their attention long enough to get accurate results.

(Contributed by Lynn Moore at 18 Jan 1994.)

The ABR is not a threshold test, generally. In fact, it really is not a test of hearing, but rather is a test of neural synchrony. We do use it to predict hearing, and it usually does a good job. However, depending upon the test parameters used, your findings may be anywhere from 10-20dB or so higher than the actual hearing thresholds. So usually the hearing is a little better than it appears on the ABR.

Otoacoustic Emissions

(Contributed by Lynn Moore at 18 Jan 1994.)

Another test which can be applied to infants is Otoacoustic Emissions. Presently this test is mostly used as a screening tool, and primarily in infants. It can separate the normals fronm the abnormal hearing, but it does not tell you the degree of loss if one exists. Also, as in ABR, middle ear disorders can cause some problems in interpretation. Used together, and with some other procedures, the two tests are a very good battery for testing infants/children (and adults also, but we frequently have a different purpose in mind when testing adults).