Deriving additional information from information presently known commonly used in audio terms as interpolating surround and center channel information in a matrixed surround sound system from the left and right front channels (creating four channels from two). Interpolation can be anything derived from other data (for instance, some electronic equipment attempts to interpolate or derive high or low frequency data from a recording even though that data has been eliminated). nterpolation is used most commonly in matrixed surround sound systems to derive four channels of information from two. The two main channels are specially encoded with the additional information. When they are played back and properly decoded, the two additional channels can be extracted. This is the process behind analog Dolby Surround sound technologies (the newer digital technologies have fully independent or discrete channels which do not require interpolation or decoding).