Surround Sound Formats

5.1, 6.1, Dolby this, Dolby that. But what does it all mean!? It means freakishly lifelike surround sound! The company was created by Ray Dolby and initially developed noise reduction systems. Now Dolby is instantly equated with surround sound in cinema, DVDs, and video games.

When picking out your receiver, one of the things that you should pay attention to is the formats of surround sound that they have available. This is important because it will directly influence how you listen and perceive the sound that comes from your home theater speakers.

Dolby Pro Logic used to be the surround sound format of choice for a very long time. It is still very common to see it nowadays too. It uses four channels of sound, three though three speakers in the front, (one left, one right and one center), and one shared by the two surround speakers, (surround left and surround right). This format is called "matrixed multichanneled" meaning that the sound output to the speakers isn't 4 separate channels. Some of the channels are built from the others. For this reason, Dolby Pro Logic often doesn't give extreme differentiation in your sound sometimes.

5.1 refers to the layout of your speakers in your surround sound setup. Not necessarily where they are placed, but more precisely how many of them there are. The "5" refers to 5 "normal" speakers...Two in the front, one in the middle front, and two on the sides near the back of the center listening position. The ".1" refers to the subwoofer. It gets the .1 because the range of frequencies the sub will receive are much narrower than the other speakers, (3-120 Hz compared to 3-20,000 Hz).

Dolby Pro Logic II processes stereo sound into five channels of surround sound. Pretty cool huh? So if you're playing something connected to your receiver that's mixed in Dolby Pro Logic or stereo, Dolby Pro Logic II can whip it up into something that sounds a lot more enveloping i.e. 5.1 sound. It's a pretty cool technology especially for video games. Game makers can encode 5.1 information into a stereo signal and allow a receiver with Dolby Pro Logic II to decode the signal for some super surround sound! Working this way allows the game system more processor power to worry about other things like graphics and physics.

Dolby Digital, (while really a method to recording audio), is commonly known as/to be 5.1 sound. It is the most popular of surround sound formats and is the chosen audio format for HDTVs and DVDs. Dolby Digital is known as a "discrete" multichannel technology. That means that all the sound output to each speaker is completely independent from the other. With six discrete sound signals, (5 speakers + sub), sound can be more accurately delivered to your ears to achieve various effects.

DTS is the surround sound technology started by Digital Theater Systems. Have you realized what their initials are? That's right, DTS. Essentially, DTS is a 5.1 surround sound format but it uses less compression than Dolby Digital. On account of this, a lot of people feel you get better sound in the end.

There are yet a few more surround sound formats that you need to be aware of. If you're ready, read on!

1, Page 2 (I'm Surrounded! 6.1 and 7.1)

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