[A study of auditory screening in infant by evoked otoacoustic emission (EOAE)]

The EOAE measuring system was newly developed for infants and the clinical study of the auditory screening for large number of infants using this system was reported. The EOAE measuring system for adults was adjusted as the system for infants. The more compact recording probe than that for adults was prepared. The noise of breathing sound and body movement were rejected during measurements by the artifact rejection system of the signal processor. ABR and EOAE were measured in 166 ears of 85 infants suspected of hearing loss ranging in age between 5 days and 5 years. Twenty-nine infants' EOAEs were measured under awaking. 1.5kHz short tone bursts (35dBnHL and -10dBnHL) was used for stimulating sound in EOAE measuring, and the 100-300 epochs were averaged. The positive response in EOAE was judged by the presence of the obvious peak in 8-10ms after stimulation and confirmation of the reproducibility of this response. The responses evoked by the two different stimulations were also compared for accurate judgement. Ninty-five ears with hearing loss over 35dB in ABR were detected no responses in EOAEs on 35dBnHL stimulation. Fifty-nine ears judged as normal hearing within 30dB in ABR showed good responses in EOAEs, but 6 ears judged as normal hearing in ABR were detected no responses in EOAEs, but 6 ears judged as normal hearing in ABR were detected no responses in EOAE. The latter 6 ears were suspected of secretory otitis media in following examinations. Three cases with abnormal waveforms judged as "unevaluable" in ABR showed good responses in EOAEs indicating their normal cochlear functions. EOAE measurement in infants was easy, speedy and noninvasive. Moreover, the response of EOAEs was clearly obtained with accuracy. Considering these facts, EOAE is suitable examination for detection of hearing impairment and is a useful auditory screening in infants.