Reduction of loudspeaker polar response aberrations through the application of psychoacoustic error concealment

In a loudspeaker system it is important to have a well controlled polar response: however, with conventional multidriver enclosures off-axis phase cancellation will occur at and around the crossover frequency. To generate a uniform polar radiation pattern from any given imperfect loudspeaker cabinet, it is necessary to reduce the perceived off-axis phase cancellation due to the crossover filters. The paper proposes a correction strategy, which is then evaluated in terms of the perceived improvement. By making use of the psychoacoustic theory of masking, and developing a new strategy for time-varying filters, a creative solution was found whereby the crossover filters cause the phase cancellation to be masked from the listener, rendering it inaudible. The proposed strategy is tested using both auditory models and actual listeners as arbiters of performance. Both test methods confirm that with the proposed strategy an improvement in sound quality at an off-axis position is obtained. The on-axis sound, unaffected, remains the in-phase sum of the loudspeaker driver outputs