Impedance of an Orifice in Nonlinear Regimes with Grazing Flow

The results of experimental studies of the acoustic impedance of circular orifices in a wide range of the sound pressure level and the presence of a grazing flow are presented. Plates of 2 mm thick with an orifice of 5 and 10 mm in diameter were used. The dependences of the real and imaginary parts of the orifice impedance on the sound pressure levels and air flow velocity at frequencies of 150 Hz and 300 Hz are evaluated.