SUPPRESSION OF TRANSIENTS IN TIME-VARYING RECURSIVE FILTERS FOR AUDIO SIGNALS

Vesa Välimäki¹ and Timo I. Laakso²

¹ Helsinki University of Technology, Laboratory of Acoustics and Audio Signal Processing, P.O. Box 3000, FIN-02015 HUT, Espoo, Finland, URL: http://www.acoustics.hut.fi/~vpv/

² Helsinki University of Technology, Laboratory of Telecommunications Technology, P.O. Box 3000, FIN-02015 HUT, Espoo, Finland

ABSTRACT

A new method for suppressing transients in time-varying recursive filters is proposed. The technique is based on modifying the state variables when the filter coefficients are changed so that the filter enters a new state smoothly without transient attacks, as originally proposed by Zetterberg and Zhang. In this contribution we modify the Zetterberg-Zhang algorithm to render it feasible for efficient implementation. We explain how to determine an optimal transient suppresser to cancel the transients down to a desired level at the minimum complexity of implementation. The application of the method to time-varying all-pole and direct-form II filter structures is studied. The algorithm may be generalized for any recursive filter structure. The transient suppression technique finds applications in audio signal processing where the characteristics of a recursive filter needs to be changed in real time, such as in music synthesis, auralization, and equalization.

Keywords: audio signal processing, digital filter design, digital signal processing, IIR filter, recursive filtering, transient, variable filter

This paper was published in the Proceedings of the 1998 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP'98), vol. 6, pp. 3569-3572, Seattle, Washington, May 12-15, 1998.

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This URL: http://www.acoustics.hut.fi/~vpv/publications/icassp98-trel.htm
Last modified: 15 July, 1998
Author: Vesa Välimäki