ABSTRACT

At high frequencies, sound makes its way around the body of the microphone and through any acoustically transparent covers, through processes of diffraction and reflection. Practical-sized pressure microphones "roll off' sound coming from the rear at high frequencies. The high-frequency rise on axis in an uncorrected pressure microphone was initially used to add "clarity" to recordings because almost inevitably in older recording equipment there would be a high-frequency loss somewhere that the microphone was useful in overcoming. Pressure microphones are used in real rooms with mixed-sound fields, with the diaphragm oriented perpendicular to the direct sound, thus eliminating the effect of the congestion on the direct sound. For low frequencies, a pressure microphone may respond all the way down into the infrasonic region. A special pressure microphone has been developed for placement on a large barrier, such as the walls or ceiling of a room.