The excitation of sandwich plates by the acoustic coincidence effect is first discussed. A Fourier analysis is then carried out to find the bond normal stress in a sandwich plate excited by general random noise pressures. The general solution is then restricted to the plane wave excitation of a sandwich beam. The effect of inclining the plane waves at the correct angle for coincidence effect excitation is discussed and calculations are made for a sandwich beam of typical dimensions. It is found that, compared with normal incidence plane wave excitation, coincidence effect excitation can produce larger stresses. It is particularly noteworthy that several of the higher order modes of vibration of the beam can be excited in a near coincidence condition at the same angle of plane wave incidence. This is because the flexural wave velocity in sandwich plates is almost independent of frequency at shorter wavelengths.