Sound pressure analysis (SPA) can be used to analyze the sound pressure generated by the vibration of a system surface based on the Rayleigh Integral, which assumes that a rigid body piston moves in a normal direction and its surface is compressed and transformed by velocity. SPA based on the Rayleigh integral is useful in mid-range frequencies (100~10k) and the global pattern is very similar with an Acoustic Anechoic Chamber (or semi-anechoic chamber) result. Before the analysis, the bodies that are the source of the sound pressure must be defined as FE or EasyFlex bodies in the preprocessor.