PORTAL is an interactive performance tool that uses a laser projector to visualize computer-generated audio signals. In this paper, we first offer an overview of earlier work on audiovisual and laser art that inspired the current project. We then discuss our own implementation, focusing not only on the technical issues related to the use of a laser projector in an artistic context, but also on the aesthetic considerations in dealing with the translation of sounds into visuals, and vice versa. We provide detailed descriptions of our hardware implementation, our software system, and its desktop and mobile interfaces, which are made available online. Finally, we offer the results of a user study we conducted in the form of an interactive online survey on audience perception of the relationship between analogous sounds and visuals, which was explored as part of our performance practice.