Digital audio filters whose parameters vary with time are analyzed according to the Time-Varying filter theory. Such a theory allows for recursive filter realization using finite order difference equations with time-varying coefficients. With this approach, the errors occurring during parameter transitions can be evaluated. It was found that such errors were significant for abrupt variation in filter parameters. A real-time microprocessor implementation for such a filter is also presented. Using a novel test, the real-time output of the varying filter was evaluated, so that perceived filter transition discontinuities could be detected.
This paper costs $33 for non-members and is free for AES members and E-Library subscribers.