Posted on January 29, 2014 at 10:58The frequency response of a microphone can vary across the audio frequency band depending on three parameters: the ventilation hole, the front chamber geometry, and back chamber geometry. The ventilation hole and the back chamber geometry have an impact on the behavior at low frequencies while the behavior at high frequencies depends on the geometry of the front chamber only. Behavior at high frequencies can be a resonance peak caused by the Helmholtz effect. This resonance is the phenomenon of air resonance in a cavity. As a matter of fact, it depends on the dimension of the front chamber of the microphone, representing the sound cavity in which the air resonates. A microphone with a flat frequency response is suitable when natural sound and high intelligibility of the system is required.
The best way to evaluate the frequency response is a relative measurement of the sensitivity, across the entire audio band, with respect to a flat calibrated reference microphone. In order to measure the frequency response in such way it is strongly recommended to use a professional calibrated microphone as reference.
Regards,
Alessandro
