STAPEDIUS REFLEX AND EABR THRESHOLDS IN EXPERIENCED USERS OF THE NUCLEUS COCHLEAR IMPLANT

Evoked auditory brainstem responses (EABR) and stapedius reflex thresh olds were established in 7 experienced users of the Nucleus cochlear i mplant. Even using biphasic 400 mus/phase clicks for the EABR, respons es were observed in only 5 patients; no stapedius reflex (SR) was seen in 3 patients, 2 of whom had a history of middle-ear disorder. The EA BR threshold varied widely between subjective threshold and uncomforta ble loudness level (ULL) for the same stimulus. The average SR thresho ld was found somewhat more consistently at 66% of the dynamic range be tween threshold and ULL, but grossly overestimated the most comfortabl e level (MCL) in most cases. To obtain equal loudness at the same curr ent level we suggest that broad clicks (300 mus/phase) be used for EAB R measurements, thus compensating for the lower repetition rate of EAB R stimulus compared with the device fitting stimulus.