Choppy and Derszogger, the exact citation is 560:25. This is what he says:??? ????? ???”? ??? ???? ???? ????? ?????? ??? ????? ?????? ??? ??.
Only songs with immodest content are prohibited.He does not mention niggunim without words although if the tune will remind a person of the filthy content that would obviously also be assur even just for himself (as the MB goes on to say).