laserdisc A format for storing analog video signals on a 12-inch double-sided disc.

LCD (liquid crystal display) A technology for displaying images. Light is projected through an array of crystals that either pass or block light, according to the signal driving the panel.

LCD projector A projector using three LCD panels and a light source.

LCoS (liquid crystal on silicon) A technology for displaying images. Used in rear-projection televisions and front projectors. Similar to LCD, but in LCoS, light is selectively reflected from pixels in the LCoS panel. (By contrast, LCD is a “trans-missive” technology in which light passes through the pixels rather than being reflected by them.)

letterbox A video image that results from displaying an image of widescreen aspect ratio on a television set of standard aspect ratio. The picture is presented between black bars above and below the image. Contrast with “windowbox.”

LFE See “Low Frequency Effects.”

linear tracks The audio tracks recorded on VHS tape as thin stripes along the tape edge. Recorded and played back by a stationary head. The slow tape speed of VHS results in poor sound quality. Different from HiFi tracks, in which the audio is recorded along with the video by the spinning video head for higher audio quality.

line level An audio signal with an amplitude of approximately 1V to 2V. Audio components interface at line level through interconnects. Contrasted with “speaker level,” the much more powerful signal that drives speakers.

liquid crystal display See “LCD.”

liquid crystal on silicon See “LCoS.”

LNB (Low-Noise Blocking Converter) A device inside a DBS dish that picks up the transmitted digital video signal.

localization The ability to detect the directionality of sounds.

low-cut filter A circuit than removes bass frequencies from an audio signal. Also called a “high-pass filter.”

Low Frequency Effects (LFE) A separate channel in the Dolby Digital format reserved for low-bass effects, such as explosions. The LFE channel is the “.1” channel in a 5.1-channel format.

low-noise blocking converter See “LNB.”

low-pass filter A circuit that removes midrange and treble frequencies from an audio signal. Also called a “high-cut filter.”

loudspeaker A device that converts an electrical audio signal into sound. The loudspeaker is the last component of the audio playback chain.

luminance The black-and-white, or brightness, component of a video signal. Represented by the letter Y.