Acoustics: Sound Fields, Transducers and Vibration, 2nd Edition

5.2. Pressure-gradient microphones

A pressure-gradient microphone is one that responds to a difference in pressure at two closely spaced points. A common example of this type of microphone has a diaphragm, both sides of which are exposed to the sound wave. Such a construction is shown in Fig. 5.4.

Figure 5.4 Sketch of a pressure-gradient microphone consisting of a movable diaphragm, both sides exposed, connected to a transducing element.

If a pressure-gradient microphone is placed in the cavity of Fig. 5.2a, there will be no net force acting on the diaphragm and its output will be zero. This happens because there is no pressure ...