a system and method for increasing the efficacy of stimulation signal therapy applied to selected tissue at a treatment site is disclosed . the method includes determining a stimulation signal capable of effecting desired results on the selected tissue and selectively modulating the stimulation signal such that the desired effect is achieved at the treatment site . the system includes a signal generator capable of generating a stimulation signal configured to produce a desired biologic effect on selected tissue at the treatment site , a modulator configured to selectively modulate the stimulation signal such that the stimulation signal correlates with at least one characteristic of the selected tissue and an emitter configured to apply the stimulation signal to the selected tissue .