Book on DAFX - Digital Audio Effects Edited by Udo Zölzer ISBN: 0-471-49078-4 John Wiley & Sons, 2002

Chapter 3

P. Dutilleux and U. Zölzer

Delays can be experienced in acoustical spaces. A sound wave reflected by a wall will be superimposed on the sound wave coming from the source. If the wall is far away, such as a cliff, we will hear an echo. If the wall is close to us, we will notice the reflections through a modification of the sound color. Repeated reflections can appear between parallel boundaries. In a room, such reflections will be called flatter echos. We introduce basic structures for delays in feedforward/feedback configuration and show several delay-based audio effects such as vibrato, flanger, chorus, slapback and echo. Extensions toward multiband applications will also be considered.

Contents

• Introduction
• Basic Delay Structures
  • FIR Comb Filter
  • IIR Comb Filter
  • Universal Comb Filter
  • Fractional Delay Lines
• Delay-based Audio Effects
  • Vibrato
  • Flanger, Chorus, Slapback and Echo
  • Multiband Effects
  • Natural Sounding Comb Filter
• Conclusion
• Sound and Music
• Bibliography

Keywords: Delays, Delay Lines, Delay Effects, Fractional Delay Lines, Vibrato, Flanger, Chorus, Echo

Contents