Home theater systems continue to evolve and change to keep up with the technology advances of the commercial cinema. Some of the latest home theater design changes involve adding new surround-sound speaker channels.
The most common home theater speaker configuration remains 5.1 (pronounced "five point one"). This layout harkens back to the late-'70s, mimicking Dolby's commercial surround format.
The 5.1 layout refers to five speakers which are arranged with three in the front of the room by the display (front left, center and front right), and then two rear or surround speakers usually at the back of the room (surround left and surround right). The .1 channel - also known as LFE for Low Frequency Effects - is the subwoofer, providing extra impact for loud bass signals like explosions or dinosaur foot stomps.
6.1 or 7.1 Surround
With the introduction of Star Wars: Episode I - The Phantom Menace, George Lucas teamed with Dolby Laboratories to add a new surround channel that allowed sound designers to place sounds directly behind the listener. This surround back channel, also called EX by Dolby and ES by DTS, quickly ported to home theater installations as either a single speaker - 6.1 - or two speakers - 7.1.
In this installation scheme, the surround speakers are moved closer to the sides of the listening position and the new channels are added directly behind the listeners.
Height and Width Channels
Most recently, surround sound decoding has added new height channels. These speakers are designed to add a third dimension to the listening experience, creating a much taller front soundscape. Height channels install several feet above and slightly outside the front left and right channels and handle ambient sound effects like wind and rain or vertical sounds such as jet flyovers.
Both Audyssey and DTS support an additional pair of audio channels known as width. These channels are installed approximately 60 degrees wide of the center channel speaker-well to the left and right of the main front channels and back toward the side surround speakers. This creates a wider soundstage and better blending between the front and side/rear channels.
Currently, there are no movies that have been recorded with height or width material. The information for these channels is extrapolated by the audio processor.
Most current audio/video receivers or surround-sound processors support 7.1 in the form of surround back channels. Many new mid-range and high-end models add the ability to do either surround back or front height or front width channels, often limited to seven channels at once.
Others will allow up to nine channels of audio, with surround back and either front height or width. A small number of flagship models allow for all of these new channels to be processed and driven at once, creating an 11-channel, fully immersive home theater experience.
To learn more about having a custom home theater designed or to have a multi-channel home theater speaker system professionally installed in your home, search for a local qualified CEDIA member home technology professional near you.