Analysis of traditional and reverberation-reducing methods of room equalization

Traditionally, electronic equalization has used linear filters of low complexity. The nature of spectral and temporal distortions of rooms limits useful equalization to minimum-phase filters of relatively low order, despite the existence of new and powerful digital signal processing tools. The high Q and non-minimum-phase nature of the room-loudspeaker-listener transfer function, caused by wave interference effects, creates severe problems for more complete equalization. A typical professional listening room and three cinema acoustic environments were used to investigate the difficulties inherent for more ambitious equalization approaches.