Artificial Reverberation

This chapter summarizes basic results in systems for artificial reverberation. Such systems make extensive use of tapped delay lines, comb filters, and allpass filters (described in the previous chapter).

• The Reverberation Problem
  • Exact Reverb via Transfer-Function Modeling
  • Complexity of Exact Reverberation
  • Possibility of a Physical Reverb Model
  
  
• Perceptual Aspects of Reverberation
  • Perception of Echo Density and Mode Density
  • Perceptual Metrics for Ideal Reverberation
    • Energy Decay Curve
    • Energy Decay Relief
  
  
• Early Reflections
• Late Reverberation Approximations
  • Desired Qualities in Late Reverberation
  • Schroeder Allpass Sections
  • Nested Allpass Filters
  
  
• Schroeder Reverberators
  • Example Schroeder Reverberators
  
  
• Freeverb
  • Freeverb Main Loop
  • Lowpass-Feedback Comb Filter
  • Freeverb Allpass Approximation
  • Conclusions
  
  
• FDN Reverberation
  • History of FDNs for Artificial Reverberation
  • Choice of Lossless Feedback Matrix
    • Hadamard Matrix
    • Householder Feedback Matrix
    • Householder Reflections
    • Most General Lossless Feedback Matrices
    • Triangular Feedback Matrices
  • Choice of Delay Lengths
    • Mean Free Path
    • Mode Density Requirement
    • Prime Power Delay-Line Lengths
  • Achieving Desired Reverberation Times
    • Conformal Map Interpretation of Damping Substitution
    • Damping Filters for Reverberation Delay Lines
  • Delay-Line Damping Filter Design
    • First-Order Delay-Filter Design
    • Orthogonalized First-Order Delay-Filter Design
    • Multiband Delay-Filter Design
  • Spectral Coloration Equalizer
  • Tonal Correction Filter
  • FDNs as Digital Waveguide Networks
  • FDN Reverberators in Faust
  • Zita-Rev1
    • Zita-Rev1 Delay-Line Filters
  • Further Extensions
    • Spatialization of Reverberant Reflections
    • Distribution of Mode Frequencies
    • Digital Waveguide Reverberators
    • The Digital Waveguide Mesh for Reverberation
    • Time Varying Reverberators
  
  
• Scattering Delay Networks