Auditory steady-state response in cochlear implant patients

Introduction and objective: Auditory steady state responses to continuous amplitude modulated tones at rates between 70 and 110 Hz, have been proposed as a feasible alternative to objective frequency specific audiometry in cochlear implant subjects. The aim of the present study is to obtain physiological thresholds by means of auditory steady-state response in cochlear implant patients (Clarion HiRes 90K), with acoustic stimulation, on free field conditions and to verify its biological origin. Methods: 11 subjects comprised the sample. Four amplitude modulated tones of 500, 1000, 2000 and 4000 Hz were used as stimuli, using the multiple frequency technique. The recording of auditory steady-state response was also recorded at 0 dB HL of intensity, non-specific stimulus and using a masking technique. Results: The study enabled the electrophysiological thresholds to be obtained for each subject of the explored sample. There were no auditory steady-state responses at either 0 dB or non-specific stimulus recordings. It was possible to obtain the masking thresholds. A difference was identified between behavioral and electrophysiological thresholds of −6 ± 16, −2 ± 13, 0 ± 22 and −8 ± 18 dB at frequencies of 500, 1000, 2000 and 4000 Hz respectively. Conclusions: The auditory steady state response seems to be a suitable technique to evaluate the hearing threshold in cochlear implant subjects.