The philosophy of electronic room enhancement
Mark A. Poletti · The Journal of the Acoustical Society of America · 2000
The acoustic design of rooms involves the determination of surface materials to provide a desired reverberation time, loudness, and diffusion. These acoustic properties are similar for sources and receivers throughout the room, and are therefore global. They are derived from the later part of room impulse responses. Reflecting surfaces are typically included to direct early energy from the stage area onto the audience areas. They operate locally for sources in the stage area, and produce more localized effects at different receiving positions. The acoustic effects are determined from the early part of room impulse responses. This paper argues that the design of electronic room enhancement systems should follow a similar philosophy to that of passive rooms. Those properties that are global, such as the reverberation time, should be enhanced using a system which can maintain this global property. This is ensured by using non-in-line systems which use microphones spaced throughout the room. Local properties are most effectively controlled using in-line systems which use microphones close to the stage area. A review of non-in-line and in-line enhancement systems will be presented, and a hybrid system introduced which aims to provide both global and local control of room acoustics.