Integral Equation for Frequency Averaged Quadratic Pressure

Integral equation for Frequency Averaged Quadratic Pressure is derived based on one single assumption: statistical independence of Green's function and boundary pressure and velocity of the radiating object. Three sources are responsible for radiation, they include cross contribution associated to surface effect, the cross velocity source, the cross intensity source and the cross pressure source. The validity of the theoretical formulation is checked on the pulsating sphere problem. The frequency averaging does not suppress the irregular frequency problem appearing in classical Kirchhoff integral equation and regularization methods have to be used in a similar way to avoid the instability of the calculation. Diffraction of a screen placed in the acoustic field is studied to demonstrate how the method can be applied to a general cases.