According to the invention, a hearing instrument comprising at least one inner
microphone operable to determine a sensing
signal representative of an acoustic
signal at a position in front of the user's
eardrum—which may be an acoustic
signal at a position between an ITE (or ITC or CIC) hearing instrument and the
eardrum or between an earpiece and the
eardrum—is used. In accordance with the invention, in front of the eardrum an acoustic signal is produced. The inner
microphone creates a sensing signal representative of the acoustic signal, and the
signal processing unit of the hearing instrument determines a characteristic of the user's
ear canal based thereon and memorizes values indicative of the characteristic. According to a preferred embodiment, the characteristic is an acoustic
coupling transfer characteristic, which is determined based on a comparison of a signal representative of the output signal of the
signal processing unit's
digital signal processing stage and the sensing signal. In contrast to the state of the art, no control loop is necessary to adapt the
gain to the
ear canal characteristic, but the memorized values may be used therefor.