US Patent 8983105 Microphone

A microphone is disclosed in which a housing is formed by a cap (13) sealed to a substrate (11). A MEMS die (10) is mounted on the substrate (11), the MEMS die (10) incorporating a membrane (12). The membrane (12) has a first surface facing the substrate and in fluid communication with an acoustic inlet port (14) in the cap (13) via an acoustic path (17) and a second surface facing the inner surface of the cap, which second surface along with part of the inner surface of the cap (13) defines at least part of a sealed chamber (19) within which a volume of air is trapped.