Pseudo-stereo
need for pseudo-stereo techniques arose with the development of commercial stereo reproduction and distribution, to attempt to bring existing mono audio material into the new medium
Decorrelation
defined by Kendall as the “process whereby an audio source signal is transformed into multiple output signals with waveforms that appear different to each other but which sound the same as the source”
Sub-band decorrelation
Potard and Burnett [Potard and Burnett, 2004] propose an enhancement to Kendall’s all-pass filtering technique by decomposing the sound into three sub-bands (Low 0-1kHz, Mid 1-4 kHz and High 4-20 kHz) to enable different amount of decorrelation for each band
Bouèri and Kyirakakis proposed a method of artificial decorrelation [Bouèri and Kyirakakis, 2004]. It uses random time shifts (< 50ms) applied to filtered bands of the signal. It suggested splitting the original audio into ERB (Equivalent Rectangular Bands) using a bank linear-phase band pass filters.