Ambisonic reproduction of directionality in surround-sound systems

In both the technology and the aesthetics of extending high fidelity reproduction to surround-sound, reproduction of natural ambience is crucial. The ‘quadraphonic’ attempt to reproduce four stereo-blended tracks, derived from multi-microphone mix-down, cannot provide this. Complete spherical directionality can however be encoded on to a minimum of two audio channels to produce acoustically acceptable surround-sound systems. Limitations are set both by the number of available loudspeakers and by the number of channels.