Surrounding Yourself with Sound in Your Home Theater
Unless you plan on installing a 360-degree Cinema-in-the-Round screen in your home, just like you'd see at Disney World, video plays a rather confined (but still big) role in creating the home theater illusion of "being" in the movie. The real job of surrounding yourself in the scene falls to your multichannel surround sound audio system.
Imagine that you see on the screen the soon-to-be victims of a firing squad, and from behind you, you hear the clicks of the rifles as they chamber a round. Your rear channel-driven surround sound system brings you that sensation. Hearing that sound coming from in front of you, when you can't see the firing squad, simply doesn't carry the same weight.
Two-channel sound versus multichannel surround sound
Most of us are used to age-old two-channel sound — the stereo sound that gives us a left and a right speaker effect. Multi-channel surround sound builds on this presentation by adding a front center speaker between the front left and right speakers and adding two surround speakers. Some versions of surround sound add two more rear speakers and side surround speakers to really enhance your surround-sound field.
So imagine a scene that shows a squadron of jets doing a fly-by of the carrier command bridge. If we were in the command bridge, we would hear the jets coming in from the left, sweeping across in front of us, and then disappearing to the right and the rear as they turn off to the starboard side of the ship. If you're sitting in a well-tuned home theater, you should hear no differently. And in fact, as the bridge shakes, your subwoofers (and bass shakers) give you the vibrations to make you feel like you're actually there.
In a 2-channel system, you may hear some of that effect because it may get the left and right part correct. A 2-channel system can't help with the front to back movement, however, and that's the critical part of a surround sound system — it surrounds you!
Understanding surround sound lingo
For the most part, the entertainment industry boils down a lot of the surround sound terminology into numbers, such as 2.0, 5.1, and 7.1. Sometimes these numbers refer to the playback system's speaker configuration, and sometimes they refer to the audio signal format. You may find the lingo confusing, especially when the speakers don't match the audio signals. In these numbers, the first number represents the number of speakers or main audio channels involved, and the 1 or 0 after the decimal point tells you whether or not the system has a subwoofer or supports a low frequency effects channel. Systems that end in 1 have a subwoofer or an effects channel.
Here's a rundown of the different numbers that you may encounter and what they mean:
- 2.0: Normal stereo, which has a left and a right channel, is 2.0 in surround-sound speak.
- 5.1: This is the primary format for creating and delivering surround sound. Movie theaters, digital television, DVD-Video and Audio, and even the latest game consoles use this format. Source signals have the five main channels and one LFE bass effects channel. Playback systems usually have five main speakers and one subwoofer.
- 5.1-channel ready: Such an audio system has six discrete inputs to accept a 5.1 signal from a signal source such as a 5.1-channel DVD player. These products can't necessarily decode signals to a 5.1-channel output. You can best ferret out true 5.1 systems by reading reviews of the devices before you buy.
- 6.1: 6.1-channel systems have an additional surround channel called theback surround channel. This channel drives a speaker (or preferably two) situated right behind the viewers, which in essence provides the same smooth flow in the back sound field that the center speaker enables in the front speaker group. Dozens of DVDs are encoded with extra back surround information for this back surround speaker, and these DVDs also play perfectly well on regular 5.1 systems.
- 7.1: Not to be outdone, some technical whizzes have taken the 5.1 or 6.1 channel encoding on a DVD and used some computer horsepower to create two, independent back surround speakers for even more surround sound, making it 7.1. 7.1 isn't a true surround sound format (there are no DVDs on the market with 7.1 channels of sound).
- 8.1 and beyond: You may hear about even higher designations, 8.1, 9.1, 10.2, and so on. These systems belong in the realm of the home theaterphile, and if you're evaluating such gear, you probably have a home theater consultant standing next to you, so just follow his or her recommendations.
Bass management is how your home theater manages the low frequency sounds. Better A/V receivers and other controller devices have several options for how you want to handle the bass sounds in your system. If you have nice tall speakers that have a very effective bass range of their own (often called full range speakers), you may decide to pass all bass frequencies to them. If you want smaller speakers that can sit on a shelf, then the bass frequencies might fall to the subwoofer (a speaker designed to play low-frequency sounds).
You don't have to have a subwoofer to take advantage of the LFE (Low Frequency Effect) channel that some DVDs have encoded because many normal left/right speakers can take these cues from your receiver and play the sound accordingly. But having a subwoofer gives you that stomach-rattling, vibrating-room effect at just the right times.