5. CSOUND SPATIAL AUDIO EXAMPLES

Below are working Csound implementations demonstrating spatial reverberation and 3D audio processing:

1. Reverberation Modeling

This example demonstrates how an instrument signal is processed through early delay taps and an artificial reverberator to create room depth:

Orchestra File (ejemplo2.orc):

sr = 44100
kr = 4410
ksmps = 10
nchnls = 2

; Global audio bus for reverb send
ga_reverb init 0

instr 1
  ; Dry sound source
  a_sig oscil p4, p5, 1
  
  ; Send portion to global reverb bus
  ga_reverb = ga_reverb + (a_sig * 0.3)
  
  ; Output direct sound
  outs a_sig * 0.7, a_sig * 0.7
endin

instr 99 ; Master Reverberator
  ; Process global bus through stereo reverberator
  a_revL, a_revR reverbsc ga_reverb, ga_reverb, 0.85, 12000
  
  outs a_revL, a_revR
  
  ; Clear global bus for next control period
  ga_reverb = 0
endin

---

2. Binaural Spatial Movement

This implementation uses Csound’s spatial opcodes to move a sound source across the listener’s auditory field:

instr 2
  ; Frequency modulated oscillator
  k_mod oscil 20, 5, 1
  a_src oscil 10000, 440 + k_mod, 1
  
  ; Azimuth sweeps from left (-90 deg) to right (+90 deg)
  k_azim line -90, p3, 90
  k_elev init 0
  
  ; Apply 3D spatial panning / HRTF filtering
  a_left, a_right pan2 a_src, (k_azim + 90) / 180
  
  outs a_left, a_right
endin