Cardioid microphone with front and rear apertures - has acoustic resistance used to obtain desired polar cardioid characteristic

摘要

A cardioid microphone has a front and rear opening. The rear opening has an acoustic resistance either in or in close proximity to it. The object is to improve the cardioid polar characteristic without increasing the size of the microphone. The housing (1) contains a diaphragm (2) behind a front aperture (3). The rear aperture (4) has an acoustic resistance (5) close to it. The front aperture (3) also has an acoustic resistance (7) in it and the relationship between R1 (5) and R2 (7) is calculated to improve the polar characteristic.