Micromachined acoustic intensity sensor

摘要

Measurement of acoustic intensity provides information not only on the sound intensity level at the point but on the direction of sound propagation also. Acoustic intensity calculation needs the pressure information and pressure gradient information at a point. Pressure gradient at a point is obtained using pressure measurements from two closely spaced microphones and employing finite difference technique. Presently, two condenser microphones placed at a small distance apart are used for acoustic intensity measurements. These transducers require a pre-amplifier and a signal processing unit making the assembly cumbersome and possibly interfering with the sound field in view of their size. Micromachined sensors are ideal under these circumstances in view of their miniature size, low cost, high reliability and the convenience of heaving the signal processing circuitry in the same microchip close to the sensor.