Patent ID: 6914992

Claim:
A system having a microphone and a preamplifier, wherein the microphone comprises a housing having a sound inlet opening to external surroundings, a diaphragm and a backplate, the preamplifier being connected to the microphone and having a first stage with an MOS field effect transistor as an input element, wherein the system further comprises: a pressure equalization opening situated in either a wall of the housing or the diaphragm and open to air spaces within the housing and on opposing sides of the diaphragm so as to permit air flow there between, wherein the pressure equalization opening is separate from the sound inlet opening and has a diameter sized such that in an audible audio spectrum the pressure equalization opening does not make an essential contribution to suppression of low frequencies; and a high-pass filter situated at an input of a second stage within the preamplifier and at an output of the input element formed of the MOS field effect transistor.