A system, more particularly a hearing aid, consisting of a microphone and a preamplifier,
wherein the microphone comprises a housing having therein an opening to the surroundings,
a diaphragm and a backplate, while the amplifier is coupled to the system consisting
of the diaphragm and the backplate and has a field effect transistor as input element.
In the housing, in a space which is bounded by, on the one hand, the diaphragm
and, on the other, the housing wall, and which does not comprise the opening to
the surroundings, a pressure equalization opening is present, which has a diameter
such that in the audible audiospectrum it does not make an essential contribution
to the suppression of low frequencies. In the input stage of the amplifier, at
the output of the field effect transistor, a low-pass filter or a high-pass filter
or a combination thereof is arranged. Through this measure, the frequency characteristic
can be optimally influenced to suppress noise.
