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Breaking Through the Surround Sound Barrier

By Jim Bray

Confused about Dolby Surround, simulated surround, Pro Logic, Dolby Digital, DTS, and all that?

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You aren’t alone.

Surround sound isn’t the be-all and end-all of good sound, but if you want to recreate a movie theater or concert hall at home, a good surround sound system is the best way with which to do it.

In this column, I’ll outline what you really need to know about surround sound, without all the nuts and bolts. This entails glossing over a lot of technical stuff, but so what?

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Back in the 1970’s quadraphonic sound began making audio waves. True quad offered four identical channels of sound, though most quad programming was available only in a couple of less satisfying “matrix surround” (read “fudged”) methods. The hardware was expensive, competing quadraphonic formats created confusion, and a lack of software titles created frustration.

I loved quad, but it died out about the same time that Dolby Surround was wending its wonderful way into movie theaters around the world.

Dolby Surround eventually found its way to home theaters, too, but it was really just via a set of rear channel amplifiers and speakers that would carry monaural (single channel) surround information. The biggest problem with Dolby Surround was that the dialogue would come from the main front speakers, as a “ghost image” that could appear almost anywhere between the two speakers depending on where they were placed and where the viewer sat.

Dolby Pro Logic, which was more like the cinematic Dolby, changed that by adding a center front channel to the mix, ensuring that dialogue and other sounds that were supposed to originate at the TV screen actually came from there. There were also some other tweaks that, combined, made it a big step forward in terms of home theater enjoyment.

The downside was that even Pro Logic only gave you a monaural surround track that didn’t offer the full audio range. It was okay for effects like gunshots and wind noises, but it was still lacking in ultimate value.

Then came the computer and digital technology, and home theater audio took another giant step forward.

Dolby Digital (also called “AC-3”) and later, DTS (“Digital Theater Systems”), upped the ante considerably. Both formats offer five discrete, full range audio channels (three front and two surround), plus a low frequency effects (LFE) channel that cries out for a subwoofer. These five main channels and the extra channel of “oomph,” which only requires about one tenth of the bandwidth of the main channels, is referred to as a 5.1 configuration.

The five discrete channels allow for movie makers and recording technicians to put excellent sound just about anywhere in the room they want. So not only can you have high quality music coming from any direction, you can now listen to a helicopter circle the room around you as, for example, at the beginning of “Apocalypse Now.” Another excellent example of surround sound is in “Dragon Heart,” when Dennis Quaid is conversing with the dragon as flies in circles around him.

Okay, these are still just effects, but they’re definitely effective!

Dolby Digital and DTS are the two main forces in movie and home theater audio. Sony also has a system for theaters, but it hasn’t made much of a splash in homes.

Naturally, you need a decoder in your audio system to hear the surround information, but these are extremely common now.

If you’re interested in being state-of-the-art (and relative high end), you may also want to keep track of some new enhancements that supposedly promise even more home theater fun.

Dolby Digital EX and DTS ES add at least one center rear channel to make the placement of sounds even more accurate. Of course you need a new amplifier and decoder to take advantage of these discs but fortunately the software titles are “backward compatible” and will play just fine on 5.1 systems by directing the center rear signals to the other surround speakers.

I haven’t heard a 6.1 or 7.1 system yet, so I’m skeptical. Then again, I was skeptical of 5.1 until I began living with it, and now I’m hooked.

And Dolby Pro Logic II is an enhancement to the older Dolby standard, and I wouldn't worry about it too much.

When will it all end? Probably never, which is frustrating for consumers, but job security for me!

Jim Bray's technology columns are distributed by the TechnoFILE Syndicate. Copyright Jim Bray.

 

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May 5, 2010