Abstract
The efficacy of a input transducer for a implantable hearing aid was evaluated during six months after implantation to the middle ear. Auditory brain stem responses were recorded just after surgery, two weeks after surgery, two months after surjery and six months after surgery. The input transducer worked properly during six months. The inputoutput function of the transducer improved antill two weeks after surgery, then showed almost constant value antill six months after surgery. The transducer had good linearity from 35 to 80 dB SPL at 4000Hz. The characteristics of the input transducer were sufficient to use for implantable hearing aid.
