Nonlinear filtered-X second-order adaptive volterra filters for listening-room compensation

The presence of nonlinearities as well as reverberation effects severely degrades the audio quality in sound reproduction systems. In this context, many adaptive strategies have been developed to compensate for room effects. However, when nonlinear distortion becomes significant, room equalization requires the introduction of suitable solutions to tackle this problem. Linearization of loudspeakers has been deeply investigated but its combination with room equalization systems may not be so straightforward, mainly when the nonlinearities present memory. In this paper, the nonlinear system has been modeled as a Volterra filter that represents the loudspeaker tandemly connected to a linear filter that corresponds to the electroacoustic path including the enclosure and the microphone setup. Based on this structure, we introduce a nonlinear filtered-x second-order adaptive Volterra filter that uses the virtual path concept to preprocess the audio signals. Simulation results validate the performance of the new approach.