simple trigger on/trigger off software

Hello all. Wondering if anyone knows of a program that I can use to underlay bass tones to existing songs. Only software I can find is of the trigger on type (where the sound goes till it ends) I want to be able trigger on a tone, then trigger it off when switching to a different tone without having to try to use Audigy to create timed samples (i.e. 1 sec., 2 sec., 3 sec. etc), the tones are for testing speaker systems and go for about a minute each.