QSound is a type of
audio post-processing that
supposedly gives the
illusion of
surround sound from only two
speakers. It allegedly does this by altering the
stereo envelope slightly, with
phase changes and delays, such that your ears think the
sound is coming from all around you rather than just in front of you. There were a few
recordings, especially in the
early 90s that were post-processed using QSound, as well as some sound cards, like the
Gravis UltraSound, that could do the post-processing in
hardware, allowing some games to
generate quasi-3D sound.
Personally, QSound never worked for me. Music post-processed with QSound always sounded bizarre. The effect of coming from all directions seemed incredibly forced, and was not that noticeable. It also played havoc with my ears whenever I turned my head or walked around the room. Rather than sounding neat, it was incredibly annoying. Others apparently thought this as well, as I haven't seen any new pre-recorded music lately that's been post-processed with QSound.