[en] Interaction between two waves is investigated numerically for the unbounded and the bounded electron beam-plasma systems, with reference to the control of wave spectrum and the suppression of the wave due to pre-modulation of the beam. In the case of the unbounded system, deformation of the beam distribution function is occurred in relation to suppression of one wave by the other wave. While, in the case of the bounded system, occurrence of deformation depends on whether reflected beams are present or not. When injected beams are reflected at the other end, two wave interaction occurs under the constant wave energy. On the other hand, when injected beams are absorbed at the other end, suppression of one wave due to the other wave is accompanied with additional broadening of the beam distribution function. (author)