Method of encoding more than two channels of audio into a pair of analog audio channels. Matrix surround sound is encoded during production and decoded by the proper surround sound processor. he most widely used form of matrix surround sound is Dolby Pro-Logic with Dolby Surround used to a lesser degree. The Pro-Logic format separates out the center channel and a single mono surround channel by analyzing the difference between the left and right channels. The surround channel is limited in bandwidth to frequencies from 100 Hz to 7,000 Hz. The Dolby Surround format features only three channels, the left and right front stereo pair and a surround channel. Dolby Surround gives up the center channel along with some degree of fidelity in the surround channels. Pro-Logic is used most often, and Dolby Surround products should not be purchased (Pro-Logic is now very inexpensive leaving no reason to use the inferior Dolby Surround technology). ince the channels in a matrix surround sound system are not discrete (totally separate), they tend to interact with one another and bleed into one another. Analog matrixed sound does not have the high level of fidelity and signal quality found in discrete digital formats. However, matrix surround sound is encoded on almost every movie produced since around 1980 making it easy to find and use. For matrix surround sound, all you need is a stereo VCR and a Pro-Logic decoder in a receiver or preamplifier/processor along with the necessary speakers and amplification. A matrix surround sound system can be purchased fairly inexpensively and there is a lot of program material available. he matrixed format contrasts to 5.1 discrete digital formats, which feature six channels of completely separate, digital, full range audio. The digital technology, found in Dolby Digital and DTS, provides a superior sonic experience. However, it requires the addition of a digital surround sound decoder along with a digital surround sound source (typically a DVD or laserdisc player). Matrix surround sound has been a versatile technology that greatly improves the movie experience compared to straight stereo.