Chorus Effect

• The chorus effect (or ``choralizer'') makes one sound source (such as a voice) sound like many singing (or playing) in unison

• Since performance in unison is never exact, chorus effects simulate this by making independently modified copies of the input signal

• Modifications include

  (1)

  delay

  (2)

  frequency shift

  (3)

  amplitude modulation

• Typical implementations use several time-varying delay lines for (1) and (2)

• Multipath filtering and reverb provide (3) indirectly

• Before digital delay lines, analog LC ladder networks were used (e.g., in the Hammond organ)

• An efficient chorus-effect implementation may be based on multiple interpolating taps working on a single delay line

• Each tap should be individually spatialized