This article presents the results of collaboration between a composer and researchers in the context of vocal roughness and composing for voice. Our research focused on parametric control of distortion. Specifically, we present a software device that supports the manipulation and control of vocal roughness in real time, using a method based on amplitude modulation and filtering. The compositional interest in working with classically trained opera singers and with vocal distortion led us to initiate research in the signal-processing domain. Our goal was to develop a tool that could facilitate the production of distorted sounds without direct effort on the part of the singer. In this way, the singer can perform a nondistorted or lightly distorted sound, and the software tool will generate or magnify the distortion in real time.