Surface contribution of a stochastically excited panel to the radiated sound power

In many engineering applcations it is important to identifiy the regions on a vibrating structure which radiate energy to the far field. This work analytically formulates a surface contribution technique based on non-negative intensity in the wavenumber domain to investigate the surface areas on a vibrating planar structure that are contributing to the radiated sound power in the far field. The non-negative intensity is derived in terms of the cross spectrum density function of the stochastic field and the sensitivity functions of either the acoustic pressure or normal fluid particle velocity. A simply-supported baffled panel excited by a turbulent boundary layer or a diffuse acoustic field is considered to illustrate the technique. The region of the panel contributing to the radiated sound power are identified. The non-negative intensity distribution is shown to be dependent on stochastic excitation. It is also observed that the more the non-negative intensity distribution is localised within the panel surface, the more effective the panel radiates sound to the far field.