Though synthesis algorithms frequently use parameters to change the produced sound, it is not always the case that these parameters have a direct (or intuitive) correlation to the change made to the perceptual attributes—the more meaningful sound descriptors for the listener and/or musician. In this work we explore two strategies by which a perceptual descriptor, roughness, can be parameterized directly on a scale, much like how interactive sound allows for control of pitch and/or loudness. Here, roughness (often tied to dissonance) is controlled by changing either the frequency or amplitude of partials that lie within a critical band. Audio examples are provided to demonstrate use in audio mixing, sound (re)synthesis and audio effects, with two implementations made available: one for offline use and another for real-time interactive synthesis using Max/MSP.