Ambisonics is a technique for encoding sound information on a number of channels to reproduce a "3 dimensional" sound field. In the basic version, sound information is encoded into 4 channels: W, X, Y and Z. This is called the Ambisonics B-format. The W channel is the general loudness of the signal. The X, Y and Z channels are the directional components in the 3 dimensions, based on a spherical harmonic decomposition of the soundfield.