The same code module behind PcmRiff and PcmRiffADSR with frequency modulation (FM) synthesis and amplitude modulation (AM) subroutines. This is a bit complex to form a suitable demo in a short amount of time, but the FM technique is the same used by Yamaha FM synthesizers (i.e., DX-7), tone modules and sound cards. Replace your original modRiff.bas with this beastie, and your capabilities are a bit more extensive. PS - this variation *should* work just fine (not directly tested), just attenuate the modulating wave or wave mix, and life should be wonderful.