Time-Varying Delay Effects

It is often necessary for a delay line to vary in length. (Consider simulating a sound ray as in Fig.1.7 when either the source or listener is moving.) In this case, separate read and write pointers are normally used.

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Subsections

• Variable Delay Lines
• Delay-Line Interpolation
  • Linear Interpolation
  • First-Order Allpass Interpolation
    • Minimizing the Transient Response of First-Order Allpass Interpolation
  
  
• Large Delay Changes
• Specific Time-Varying Delay Effects
  • Flanging
    • Flanger Speed and Excursion
    • Flanger Depth Control
    • Flanger Inverted Mode
    • Flanger Feedback Control
    • Summary of Flanging
  • Phasing
  • Vibrato Simulation
  • Doppler Effect
    • Vector Formulation
  • Doppler Simulation
    • Doppler Simulation via Delay Lines
    • Time-Varying Delay-Line Reads
    • Multiple Read Pointers
    • Multiple Write Pointers
    • Stereo Processing
    • System Block Diagram
  • Chorus Effect
  • The Leslie
    • Rotating Horn Simulation
    • Leslie Free-Field Horn Measurements
    • Separating Horn Output from Base Leakage
  • Rotating Woofer-Port and Cabinet Simulation
  • Miscellaneous Effects
    • Doubling Simulation
    • Slap Back
  
  
• Delay Line Interpolation Problems

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written by Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.