Hello Darryl, you wrote: > [modulate a sine wave with another in SoX?] What you could do as an easy approach is modulate a sine wave with a tremolo. Assume a target bit depth of 24bit, a sample rate of 44.1kHz, a carrier of 1500Hz with a length of 20s and a modulation of 0.5Hz with a depth of 100% sox -n -b 24 -r 44100 test.wav synth 20 sine 1500 tremolo 0.5 100 Tremolo can only do a sine modulation with a fixed phase of 90°. Even more powerful is the cascading of synth effects. Same logic, the carrier is amplitude-modulated by a sine with 0.5Hz with the same 20s length: sox -n -b 24 -r 44100 test.wav synth 20 sine 1500 synth 20 sine amod 0.5 If you don't want a full modulation (from 0 to 100%), you can add a dc-offset to the second waveform. Hope this helps! Best regards, Thomas _______________________________________________ Sox-users mailing list Sox-users@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/sox-users