SACD See “Super Audio CD.”

sampling The process of converting an analog audio signal into digital form by taking periodic “snap-shots” of the audio signal at some regular interval. Each snapshot (sample) is assigned a number that represents the analog signal’s amplitude at the moment the sample was taken.

sampling frequency The rate at which samples are taken when converting analog audio to digital audio. Expressed in samples per second, or ,more commonly, in hertz; i.e., the CD format’s sampling frequency is 44.1kHz.

satellite speaker A small loudspeaker with limited bass output, designed to be used with a sub-woofer.

scaler Video processing device that changes the resolution of the input signal to a different resolution.

scan line One sweep of a beam of electrons from left to right across a CRT display; also, one horizontal line of picture information in a video signal. In the NTSC system, each video frame is composed of 525 scanning lines (of which 480 are visible).

scan rate The frequency with which a video display device “paints” scan lines. NTSC video has a scan rate of 15,734 lines per second (525 lines per frame multiplied by 29.97 frames per second), or 15.734kHz.

screen The front of a direct-view television’s CRT picture tube, the front of a rear-projection TV onto which an image is projected, or a separate material onto which a front projector projects a video image.

screen gain A measure of a screen’s reflectivity compared with a reference material. Screen gains of more than 1.0 are possible because some screens focus their reflected light over a narrow viewing area.

SDI (serial digital interface) A digital video interface that carries standard-definition video signals, but not high-definition, mostly in very high-end and professional video equipment. HD SDI carries high-definition video.

selectivity Tuner specification describing the tuner’s ability to reject unwanted stations. Good selectivity is important to those who live in cities,where stations are closely spaced on the broadcast spectrum.

SED See “Surface-conduction Electron-emitter Display.”

sensitivity A measure of how much sound a speaker produces for a given amount of input power. speaker sensitivity is measured by driving a speaker with 1W of power and measuring the sound-pressure level from a distance of 1 meter.

set-top box (STB) A device that receives and decodes digital television signals. A set-top box can also include a satellite receiver and/or a hard-disk-based digital video recorder (DVR).

shielded loudspeaker A loudspeaker lined with metal to contain magnetic energy inside the speaker. Shielded loudspeakers are used in home theater because the speaker’s magnetic energy can distort a video monitor’s picture.

sibilance S, sh, and ch sounds in spoken word or singing.

signal-to-noise ratio (S/N) Numerical value expressing in decibels the difference in level between an audio component’s noise floor and some reference signal level.

single-chip DLP A DLP-based video display in which a single DMD creates the image. A single-chip device projects the three primary colors of red, green, and blue sequentially. Contrast with three-chip products in which the three colors are projected simultaneously.

soundfield See “soundstage.”

sound-pressure level (SPL) A measure of loudness. Expressed in decibels (dB SPL).

soundstage The impression of soundspace existing in three dimensions in front of and/or around the listener.

source components A/V components that provide audio and video signals to the rest of a home-theater system. Digital video recorders, DBS dishes and receivers, and DVD players are source components.

source switching Function performed by an A/V receiver or A/V controller that selects which source component’s signals are fed to the speakers and video monitor.

spade lug A speaker termination with a flat area that fits around a binding post.

S/PDIF (Sony/Philips Digital Interface Format) Standardized method of transmitting digital audio from one component to another.

SPL See “sound-pressure level.”

speaker See “loudspeaker.”

SPL meter A device for measuring the sound pressure level created by an audio source.

spring clips Cheap speaker terminations found in budget A/V receivers.

STB See “set-top box.”

subwoofer A speaker designed to reproduce low-bass frequencies.

Super Audio CD (SACD) Disc format that can deliver high-resolution multichannel or 2-channel digital audio.

Surface-conduction Electron-emitter Display (SED) Display technology developed by Canon and Toshiba that delivers a CRT-quality picture in a flat-panel form-factor.

surround decoder A circuit or component that converts a surround-encoded audio signal into multiple audio signals that can then be amplified. A Dolby Digital decoder takes in an encoded Dolby Digital signal and outputs a 5.1-channel (left, center, right, left surround, right surround, subwoofer) audio signal.

surround decorrelation A THX technology that makes the sound in the monophonic left and right surround channels in a Dolby Surround signal slightly different.

surround delay A technique of delaying the signal to the surround channels to increase the apparent separation between the front and surround channels.

surround mode A setting on A/V receivers and A/V controllers that determines what surround decoding or signal processing is performed on the audio signal.

surround receiver See “A/V receiver.”

surround sound An audio recording and playback format that uses more than two channels, and is reproduced with two or more loudspeakers located behind the listener in addition to the loudspeakers in front.

surround speakers speakers located beside or behind the listener that reproduce the surround channels of surround-sound¬–encoded audio programs.

S-VHS A variant of the VHS tape format that provides better picture quality by storing the video signal with a wider bandwidth, and by keeping the video signal’s brightness and color information separate.

S-video A video connection method that keeps the video signal’s brightness and color information separate. Uses a 4-pin DIN connector.

SXRD (Silicon X-tal Reflective Display) Sony’s trade name for its video display technology based on LCoS. “X-tal” is cute shorthand for “crystal.”

system matching The art of combining components to create the most musical system for a given budget.