The following figure shows the geometry of the MEMS microphone:
The microphone is composed of a sound port from which the pressure waves enter and reach the membrane. The silicon moving membrane has a diameter of 0.6 mm and a thickness of 0.5 μm, and it contains holes that allow ventilation of the pressure between the two sides of the microphone. The membrane is separated from the rigid backplate by an air gap of 2.2 μm (dimensions taken from Czarny). The backplate contains perforations that play a role in the pressure distribution on both sides of the membrane and on the housing cavity, which is also part of the acoustic design.