Stapedius reflex growth function in cochlear implant patients.

The growth function of the contralateral stapedius reflex elicited by analog electrostimulation via cochlear implant was investigated in 9 patients and compared to reflex functions obtained for acoustic stimulation in 3 normal-hearing subjects. Sinusoidal signal bursts with the same time pattern were used for the two stimulation modes, the contraction of the middle ear muscle was monitored by sampling the compliance change in the contralateral ear. The reflex amplitudes were found to increase with increasing stimulus intensity in all individuals except in 1 with electrical stimulation. The slope of the intensity function for electrostimulation ranged between 5 and 85%/dB and in the acoustical mode between 2 and 4%/dB. In case of electrostimulation a frequency effect was observed.