Evaluation of OAE-recording as a complementary test method for adults with moderate to profound mental retardation

The recording of otoacoustic emissions (OAE) was evaluated as a complementary test method for adults with moderate to profound mental retardation (MR). A portable apparatus, ILO 288 Echoport linked to a Compaq LTE 5100 notebook with software ILO 88 V 4.2, was used. Otoscopy and tympanometry were also performed. Criteria for emissions were S/N 3 dB or more and reproducibility 60% or more for at least three frequency-bands. The criteria for partial emissions were the same, but for only one or two frequencies. Two examiners were needed: one to keep the tested person calm and quiet and the other to handle the keyboard. Thirty-eight people with different degrees of MR in connection with other disabilities were included. They had all exhibited incomplete results in a previous hearing screening of more than 1,000 adults with MR. Reproducible transiently evoked OAEs (TEOAE) were recorded from 11 ears (7 people), partial TEOAEs from 6 ears (4 people) and no emissions from 15 ears (10 people). Registration from 24 ears (13 people) could not be evaluated because of too much external and internal noise. Eight people rejected the examination. Only four people showed emissions in both ears. Accordingly, 34 people (89.5%) had to be re-tested or referred for further investigation, 21 of them (55%) because of noisy recordings or no co-operation. It is concluded that the TEOAE-test in its present form cannot fulfil the demands for a functioning test method for this population. In single cases, however, TEOAE-recording can complement other audiological tests.