A physically motivated room reverberation enhancement system that is stable in any (passive) room.

Abstract

Prior active room reverberation enhancement systems have typically employed microphones, artificial reverberator filters, and loudspeakers to change the reverberant properties of a room. However, acoustic feedback from the loudspeakers to the microphones has had the potential to drive such systems unstable. In contrast, techniques from feedback control can be used to design a stable room reverberation enhancement system from the ground up. A feedback controller implements a passive connection between virtual acoustic spaces, which are realized using digital waveguide networks, and special transducers, which operate concurrently as microphones and loudspeakers. Because the feedback controller models a passive system, it is theoretically stable for arbitrarily large loop gains in any (passive) acoustic environment. As a consequence, the system does not suffer from “ringing tones” at high‐loop gains in the same way as prior systems have suffered. Furthermore, the system does not need to be re‐calibrated if the properties of the room change or even if moved to a whole new room. Finally, this method for designing room reverberation enhancement systems may generally result in more realistic reverberant sound because it implements the acoustical features of a system that could exist naturally in the physical world.