One Or Two Back Surround Speakers?
Dear Gary: I am looking forward to your Ultimate Widescreen DVD Movie Guide on hybrid DVD-Video/ROM disc. Beside all the information, I am interested in the trailers. I only hope that the trailers will not be shown like on the Matrix DVD as a little part of the screen and that the trailers will be anamorphic widescreen. I am also interested in the new Surround EX/ES format. I would like to read more about this topic especially about the decision on one or two rear centers. For me it is clear: only on—just like one front center. But THX and other companies suggest two rear centers. Why?
Holger Hegele
Movie Sound Editor Perry Sun Comments:
In small listening environments for only one listener, a single speaker for the back surround might be suitable. But there are two reasons why two speakers could be preferable over one. First, a single speaker is a point source, thereby defeating the intended effect of spacious, enveloping surround sound for rooms with multiple listeners. Second, when you have sounds coming from directly in front of you, and at the same time directly behind you, you’re likely to have a difficult time differentiating between the two directions. It’s simply a psycoacoustical phenomena. So the use of two speakers can help by spreading the back surround information to yield a sensation of sound wrapping around you from behind. Editor Gary Reber Comments: I actually prefer the surround back imaging that can be derived via either a matrix back center or a discrete back center signal to form a coherent back surround soundfield similar in application to the front soundfield image derived with two front speakers and a center channel speaker. It is true that two back surround speakers will sound more diffusive, though I think that defeats the capability of mixing to create a coherent soundfield using three discrete channels—whether the actual surround back channel is delivered to the home theatre as a matrix or discrete channel.
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