Time Varying Comb Filters

Comb filters can be changed slowly over time to produce the following digital audio ``effects'', among others:

• Phasing
• Flanging
• Chorus
• Leslie

Since all of these effects involve modulating delay length over time, and since time-varying delay lines typically require interpolation, these applications will be discussed after Chapter 5 which covers variable delay lines. For now, we will pursue what can be accomplished using fixed (time-invariant) delay lines. Perhaps the most important application is artificial reverberation, addressed in Chapter 3.