Digital apodizing filters design by using B-spline functions and continuous polynomials

This paper presents a design method of the audio digital appodizing filters, by using B-spline and continuous polynomial functions in the transition frequency band. It is known that an appodizing filter can be used to control the time smear for a recording and a reproducing chain. The choice of the frequency response above 20 kHz can reduce the time extent of the impulse response. In the proposed approach, the appodizing filter is optimized with the novelty of using spline functions and continuous polynomials in the transition band. Several design examples are included to illustrate the proposed algorithm.