What do the surround channels of my Dolby® Pro Logic® or Pro Logic II system actually do?
Many listeners are often confused about the operation of the rear (surround) channels. While some assume that sound should always be coming from each speaker, most of the time there will be little or no sound in the rear channels. When there is sound, it will be diffuse and at a low level. Generally, the surround channels are used when a movie director or sound engineer specifically places sound there to create ambiance or an effect, or to pan from the front of the room to the rear. When the output levels are properly set, it is normal for the surrounds not to call attention to themselves. Artificially increasing the volume to the rear speakers may destroy the illusion of an enveloping sound field that duplicates the way you hear sound in a movie theater or concert hall.
