| 摘要 |
PROBLEM TO BE SOLVED: To stably maintain clarity and silence high by measuring a pressure supplied by the periphery of an area which can contact the periphery of the eardrum or an acoustic sensor or the distribution of the pressure, varying a gain and a phase amount corresponding to the measured pressure or distribution of the pressure and compensating the fluctuation of the acoustic transmission characteristics in cavity. SOLUTION: A gain control part 52 amplifies signals supplied through a cable 126 by a fixed gain and drives an electric/acoustic transducer 124. The acoustic signals are transmitted to the eardrum of a user at a prescribed level. Also, pressure sensors 51-1-51-N respectively supply the pressure supplied by the auricle to the corresponding part of an ear abutting member 125 to differential amplifiers 56-1-56-N as a voltage. When the pressure of one of the pressure sensors 51-1-51-N lowers and the potential of the output end of the corresponding differential amplifier is changed larger than a reference, an addition amplifier 57 updates a control voltage to be supplied to a variable gain amplifier 55.
|
