A new generation of time variant electro-acoustic enhancement systems
Steve Barbar · The Journal of the Acoustical Society of America · 2011
In 1991, Dr. David Griesinger presented a paper at the 90th AES convention [preprint 3014] describing a new method for improved electronic acoustic enhancement, and hundreds of these systems have been installed throughout the world. This paper describes a new approach to both hardware and software that comprises a third generation system. The new system retains the essential features of multichannel time variance with low pitch alteration, but updates the algorithms to utilize the superior DSP power of modern computers. Multiple reverberators, equalization, and matrix distribution can be combined into a single, reliable, and easily replaceable piece of hardware. Overall system gain and equalization can be calibrated automatically anytime; parameters in the hall have changed. The new algorithm combines the efficiency of infinite impulse response filters with direct convolution to produce a time-variant structure with extremely low coloration. The algorithm also includes a novel 32 band antifeedback circuit that further reduces coloration when the system is installed in a room. Unlike much of the competition, this system architecture allows the strength of the reverberation to be adjusted independently of the reverberation time, which makes it possible to simultaneously optimize both clarity and reverberance.