Abstract
Optimal filters for extracting time-varying harmonics such as a voiced sound from the noise-corrupted observation are proposed. They are derived through the Kalman-Bucy filter analysis in which the dynamics of amplitude and pitch fluctuations are introduced into the state-space signal model. The Laplace analysis to the filter equation leads to three types of comb filters, i.e., the uniform-BW (-bandwidth) type, the uniform-Q type and those mixture type which have robustness to the amplitude fluctuation, the pitch fluctuation and both of them, respectively. All-pole digital filters can be also realized for real-time processing. Examples of filter design are presented, and the performance of harmonics extraction is examined by comparison between the uniform-BW type and the uniform-Q type.
