I find that these sound similar except that, at low frequencies, the second sounds twice as fast as the first; but I was expecting the second to involve an audible vibrato-type effect instead of an amplitude effect: play "|sox -n -p synth 0 sin 440 vol .4" synth 60 sin am 1-500 play "|sox -n -p synth 0 sin 440 vol .4" synth 60 sin fm 1-500 ^^ I suspect I misunderstand the nature of fmod here. I thought the amplitude of the second wave would alter the frequency of the first. I was finally brought to ask this when studying today the similarity between synth amod and --combine=multiply, because I was looking for something that would let an input adjust frequency instead of amplitude. -- Doug Lee dgl@xxxxxxxx http://www.dlee.org Don't be afraid your life will end; be afraid that itwill never begin. -- Grace Hansen _______________________________________________ Sox-users mailing list Sox-users@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/sox-users