The Science of Surround Sound
Going to the movies is one of the world's favorite pastimes. Thanks to the availability of better and more affordable technology, it's now easier to recreate that theater experience in your own home. But buying a great TV is just half the battle — you need to invest in great audio as well. It's the audio that delivers theater-quality sound that makes you feel like you're in the movie when you're actually on your couch.
Surround sound is great because it offers a more realistic viewing experience. Home audio and theater audio have come a long way in the last century. In the 1930s, movie theaters had just one single large speaker to deliver audio, and it was recorded for movies as a single channel. It would be a while before we broke away from monophonic sound.
The real precursor to surround sound was the introduction of two-channel stereophonic sound, where audio would differentiate depending if it was coming from the left or right channels. All modern headphones and computers can output at least stereo sound, and it's what we generally expect for the base level of television watching these days.
Surround sound is the next step in that evolution. Here our audio isn't just set within two channels, but is presented with a minimum with a five different channels of audio.
How A Home Theater Set Up Works
To achieve surround sound audio at home, you'll need a piece of technology known as a receiver. All of your devices route their audio into the receiver, including your cable box, DVD player and game consoles. The receiver also connects to the speaker system placed around the room.
To get the full audio effects of multi-channel sound, the receiver amplifies the power of the selected audio source. It then uses the internal decoder to separate the multiple tracks encoded in the movie or show and sends that signal to the correct speakers. These speaker directions are encoded in to the audio signal by those who made the movie or television show.
Getting booming sound that envelopes the viewers requires a lot of speakers, and to make things more complicated, there isn't just one setup possibility out there. You've probably seen numbers next to surround sound designations like 5.1, 6.1, 7.1 or even 10.2. These refer to the number of speakers needed, and their position around the room.
5.1 surround sound is the most common, and the type most receivers support. The 5 represents the five speakers required: the left, center, right, right surround and left surround.
The Home Theater Setup
The left and right speakers sit on their respective sides of the television, and project the audio from each side of the screen. These sit next to the center speaker, which is necessary for grounding the audio and plays all the same sounds from the left and right channels. These three speakers play the main audio tracks, like dialogue, from the movie.
The right and left surround speakers are responsible for playing background noises, like cars passing, noise in a restaurant, and other noises that make you fee "surrounded" by the scene, thus making the movie feel more realistic.
The .1 in the name represents the low frequency effects (LFE); it's the deep bass in movies that emanates from the subwoofer, usually also positioned in front of the television.
The variants in surround sound designation represent even more speakers. 6.1 surround sound adds an additional rear-center speaker for more "three dimensional" audio, and 7.1 splits that rear speaker into two channels.
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