Volterra filters using multirate signal processing and their application to loudspeaker systems

We propose two methods for reducing the computational complexity of Volterra filters. First, a method reducing the computational complexity of Volterra filters is proposed. This method can be realized by incorporating multirate signal processing into the Volterra filters. Hence, it is possible to operate the bandlimited Volterra filter at a low sampling rate and with a short system length. Second, we also propose a method to replace the conventional Volterra filter with one including many zero coefficients by using multirate signal processing. The conventional Volterra filter is bandlimited in order to avoid aliasing so that waste arithmetic is done. In contrast, the Volterra filter including many zero coefficients derived by the proposed method can eliminate such waste arithmetic. We demonstrate their effectiveness in application to loudspeaker systems whose nonlinear distortions are generally concentrated in the lower frequency band. Even though the processed frequency band is limited, the proposed method has about 0.03 times as many computational complexities as the conventional method.