Measurement of Acoustic Impedance and Sound Absorption Performance of a Perforated Plate with a Backing Cavity at a High Sound Pressure Level

Perforated plates are effective for sound absorption and often used for noise control. In the present study, we measured the acoustic impedances of perforated plates with backing cavities of different depths when the incident sound pressure level was around 100-150 dB. The measured acoustic impedances were compared with the values predicted by an equation proposed by Guess. As the Mach number of the particle velocity through the orifice in the equation, we adopted the root mean square value of the particle velocity calculated from the measured sound pressure on the plate’s surface and the measured acoustic impedance. When the backing cavity is deep, the predicted acoustic impedance agrees with the measured value. However, apparent difference appears when the backing cavity is shallow. Some modifications on the equation are proposed.