5.1 – Surround Sound with five channels and one subwoofer.

6.1 – Surround Sound with six channels and one subwoofer.

6.2 – Surround Sound with six channels and two subwoofers.

7.1 – Surround Sound with seven channels and one subwoofer.

Audio-Video (A/V) Cable – A three-wire cable intended to carry analog stereo sound on red and either black or white color-coded cables, and composite video on a yellow-coded cable.

CD, Compact Disc – usually used to store music in a digital format. Other things can be stored (e.g. Video-CD and data on a CD-ROM or CD-RW) but this is not the typical use for home theater. There is also a new surround-sound music format called SACD (super-audio CD).

Coaxial Digital Cable – A single cable used to carry digital sound, via electrical signals, from a component (such as a DVD or CD player) to a receiver. For an alternative, see Optical Digital Cable.

Crossover / Crossover Network – High fidelity speakers usually contain more than one driver or speaker cone. Typically, a 3-way speaker has a woofer for low frequencies, a mid-range driver for most common sounds (voice and most music), and a tweeter for high sounds. The electronic device that directs the correct frequency sounds to the corresponding driver, is called the crossover.

Dolby, Dolby Digital, Dolby Surround – Dolby Labs is one of the leading proponents of Surround Sound. Their Dolby Digital surround encoding standard is the most widely used on DVD and is the standard method of sound broadcast for digital TV, including High Definition.

DTS – An alternative to Dolby Digital found on DVD's, DTS provides higher fidelity sound but takes up more space on the DVD. Most home theater receivers can decode both Dolby Digital and DTS encoded sound.

Encode/Decode (sound) – Theater sound and music historically are played through analog channels, typically two for stereo up to as many as eight for Surround Sound home theater. Encoding, for our purposes, is the conversion of these multiple analog channels into a single digital stream of data that can be stored on a CD (music) or DVD (audio and video), or can be broadcast over the air (digital TV). The digital sound takes up much less space on a DVD or CD and can be sent to a receiver from a DVD player over a single cable (optical or digital coaxial) where it is decoded back into analog channels that can be played through speakers.

IR, Infrared – A method of transmitting remote control signals to electronic devices using infrared light, which is invisble to the human eye. Most consumer remote controls use IR. This method is strictly line-of-sight and cannot be used to control devices through walls or furniture. As a result, it is often used for home theater but rarely for home automation applicatons like controlling the lights or air conditioning. See RF for a common alternative.

Invisible Speakers – Where appearance is the overriding concern, we have available several speaker models that really do disappear into your home's decor. By virtue of the design, they are undetectable as speakers unless they are actually playing. One type camouflages the speakers as various works or art. Another type results in a speaker that is indistinguishable from the surrounding wall. We do not, however, recommend outdoor speakers that are disguised as rocks.

LFE, Low Frequency Effects – These are the very low frequency sounds, usually heard through a subwoofer, which is intended to provide the “feel” of home theater movies such as an explosion or earthquake. Surround Sound standards provide an LFE channel (the “.1”) for these effects.

Optical Digital Cable – A single cable used to carry digital sound, via laser light, from a component, such as a DVD or CD player to a receiver. For an alternative, see Coaxial Digital Cable. The cable is usually made of glass fiber so it can pass light.

Pro Logic II – A digital sound processing technique from Dolby Labs that converts stereo music to surround sound in an attempt to realistically recreate the recording environment (e.g. a club, coffee house, or studio).

RF, Radio Frequency – A method of transmitting remote control signals to electronic devices using radio waves. Unlike Infrared, RF is not line-of-sight and can operate through walls. RF is often used for home automation applications like controlling the lighting since the receiver/server may be in a different room from the lights. However, RF is not commonly used for Home Theater since Viewers are usually sitting right in front of the television they are watching and IR is more immune to interference. See IR for a common alternative.

SAP, Second Audio Program – Television sound is broadcast in a primary stereo language (e.g. English). However hidden in the television signal there often is a second mono language (e.g. Spanish). Turning on SAP allows the listener to hear the alternate language. The second audio channel can also be used to provide, along with a duplication of the dialogue, a running description of the action on the screen for the visually impaired.

Subwoofer – A subwoofer is a speaker that produces very low sounds, at least some of which are too low to actually hear. Usually unnecessary for music, home theater has popularized them, because surround-sound movies, like Dolby-Digital DVD's, have special information called Low Frequency Effects or LFE. These are the sounds that make the floor shake during an earthquake or explosion. Since it can take quite a bit of energy to shake a floor, most LFE subwoofers are powered; they have their own built-in supplementary amplifier.

Surround Speakers – The side speakers, not the back speakers, in a Surround Sound system.

Surround Sound; 2.1, 5.1, 6.1, 6.2, 7.1 – These are different modes of digital sound and, except for 2.1, represent surround sound. The number before the decimal point represents the number of encoded channels. The number after the decimal point is the number of LFE or Low Frequency Effect Channels. This is almost always one, and represents the subwoofer. For example, 5.1 means two main (stereo) speakers, one center channel (for most voice) and two surround speakers (to the left and right sides, not behind, the movie-watchers) for a total of five channels. The “1,” following the decimal point (.1) means there is a channel for LFE (i.e. the floor shaking for an explosion or earthquake). This sound is usually sent to a powered subwoofer. 6.1 and 7.1 mean there are one or two additional speakers. These are placed behind the listener.

THX – An audio and video standard for movie reproduction. Originally put forward by George Lucas, this tells how a DVD player should produce a picture and how the surround sound channels should work. There are many flavors of THX including Select, Ultra, and Ultra 2. Many people contend that good THX reproduction is often not good music reproduction. Ultra 2 addressed some of this critcism.

Wireless – A system of controlling a device with a “remote.” The Remote Control can signal the device using either Infrared (IR), or Radio Frequency (RF).