For rooms with excessive natural reverberation, AFC can not deaden the space’s reverberation. Acoustical anomalies such as excessive reverberation, focused echoes, slap-back echoes, diaphragmatic surfaces, noisy rooms, vibrating or shaking floors or structures, and standing waves or room modes cannot be corrected by AFC. Traditional acoustical means or solutions must be employed for these issues. While AFC can mask flutter echo, actual correction of the echo problem requires traditional acoustical solutions. The whole point of AFC is to create natural sounding reverberation that correlates with the visual stimulus from the room. Thus, AFC will not make one room sound like another such as the YASI Piano Selection Studio cannot be made to sound like Stern Auditorium at Carnegie Hall as an example. AFC’s natural sound is assured because the reverberation tail used to start the AFC process contains the room’s impulse response signature which is then used to create the additional reverberation in the FIR filters which adds to the reverberant level and further lengthens the tail. Clients wanting unnaturally long reverberation times for effects purposes should not consider AFC which typically can only double the reverberation time at a maximum. This maximum limit is self-imposed for natural correlation of reverberation time with the visual stimulus of the room. Complex musical theater or other productions benefiting from room mapped sound effects which may or may not include added room reverberation are not possible with AFC. AFC’s magic starts by using the reverberation tail created by a sound system approaching the feedback threshold. If this reverberation tail cannot or does not exist such as is the case when the venue is outdoors or the room is completely anechoic, AFC does not function properly. Copyright (C)2009 Yamaha Corporation. All rights reserved.