16:9
Widescreen aspect ratio used for video display. The displayed image is 16 units wide (horizontal measure) by 9 units tall (vertical measure) creating a rectangular effect similar to the screen at a movie theater.
4:3
Traditional nearly square aspect ratio used for most current analog television screens and IMAX movie theater screens. Video displays using a 4-by-3 ratio display images 4 units wide (horizontal measure) by 3 units tall (vertical measure).
5.1
Five point one is a term used to describe digital surround sound audio formats such as DTS and Dolby Digital.
6.1 or 7.1
The most advanced home theater systems feature six (with Center Back) or seven (with Left Back/Right Back) full-range channels that allow viewers to take full advantage of Dolby Digital EX soundtracks and Dolby Pro Logic® IIx matrix-surround decoding technology. Both of these processes add surround information for greater realism and more dramatic effects.
5-Way Binding Post
A high-quality terminal connection able to accept multiple types of speaker wire with a variety of terminations or ends.
A/V
(Audio/Video) A/V, or Audio/Video, is a generic term used to describe products and services associated with audio and video.
AC-3
AC-3 is a proprietary digital compression scheme developed and licensed by Dolby Laboratories.
Acoustic Suspension
A type of speaker enclosure that is completely sealed with no port or other device to let air inside the enclosure flow outside the enclosure.
Acoustics
The physical properties of sound as they pertain to a particular situation.
Active Crossover
Uses electronics supplied with a power source and acting on the sound to shift sound reproduction tasks from one speaker driver to another.
Ambience
The subjective quality of a space; the feel of the space achieved through a mixture of all elements and characteristics affecting the space.
Amplifier
Electronic component that accepts a low-level signal and recreates the signal with more power; this term is most often used in audio/video to describe an audio component which takes in line-level audio signals through interconnect cables and outputs a high-powered replica of the input in order to drive speakers and create sound.
Analog
Analog refers to a non-digital continuous waveform signal, which may contain an infinite number of points along a frequency range.
Analog-to-Digital Converter
Electronic equipment used to change or convert an analog (waveform style) signal into a digital signal (made up of 1s and 0s).
Anamorphic
Process where a "wide"video image (typically in a 16-by-9 widescreen format) is compressed or squeezed horizontally to fit a more narrow video display standard but expands to full size when played over a wide video display.
Anechoic Chamber
A specially designed room in which there are no reverberations of sound waves.
Anechoic Frequency Response
The frequency response of a speaker in an anechoic chamber with no room interactions with the sound.
Antenna
Metal rod or length or wire which sends or receives electromagnetic waves.
Artifact
Referring to compressed video formats, particularly DVD and direct broadcast satellite using MPEG-2 compression, an artifact is a visual anomaly or error created when the compression system is not able to keep up with fast action or complex scenes in a video image.
Aspect Ratio
Relationship in a video image between the width of the image and the height of the image expressed in generic terms of units width by height (4:3, 16:9).
Audio
Something that is heard or having to do with something that is heard; in audio/video having primarily to do with the process of reproducing sounds through a system of electronic components.
Audio Input
In an audio/video system, the audio input is a connection on an electronic device allowing electronic signals with audio information sent by another component to enter.
Audio Output
The connection point from which an audio signal is electronically transferred via a wire from one audio component to another; the origination point of an audio signal as it travels over a wire.
Azimuth
As related to consumer direct broadcast satellite systems, the azimuth is the direction and angle needed to point the receiving dish to receive signals from the satellite.
Baffle
Front panel of a speaker enclosure on which the drivers are placed.
Balance
The degree to which two or more sound sources present an equal sound pressure level (equal loudness) when driven with the same material.
Balanced
Balanced wiring in electronics refers to wiring with two conductors in addition to a wire shield.
Banana Connector
A speaker wire termination consisting of a single, fat shaft which bulges on the sides similar to a banana and inserts in 5-way binding posts.
Band
A grouping of frequencies in the audible frequency spectrum.
Bandwidth
The frequency range across which an audio system can reproduce sound.
Barrel Distortion
Form of video distortion in which lines on the screen bow or bend outward toward the edges of the screen when they should be straight lines with no curve (or curved lines are curved more than they should be).
Basket
A component of a speaker driver which holds the various portions of the driver together.
Bass
The deepest frequencies of the audible spectrum - generally those below 200 Hz.
Bass Reflex
Type of speaker enclosure which uses a port to increase bass output for a given power input resulting in 2 to 3 dB (decibels) more sound pressure than a similar sealed enclosure (also known as an acoustic suspension enclosure).
Bi-amplify
Technique in audio where the high frequency drivers in a speaker are driven or powered separately from the low frequency drivers used in the same speaker through the use of dual binding posts on the speakers and multiple amplifiers.
Big Screen
A television or other video display devise with a diagonal screen size of 35 inches or more.
Binding Post
A means of connecting speaker wire to an amplifier or speaker.
Bipolar Speaker
Type of loudspeaker that directs sound in two directions using speaker driver on two sides of the enclosure opposite one another operating in phase (meaning that they both push out at the same time and they both come in at the same time).
Bit
The smallest piece of digital data; bits are represented by a one or a zero.
Bit Rate
The number of bits transferred in one second by a digital device such as a CD player.
Bi-wire
Technique used in connecting speakers to amplification sources in which two wires are run from each amplifier terminal to the corresponding speaker terminal instead of one.
Black Level
The level of brightness at the darkest (black) part of a visual image or the level of brightness at which no light is emitted from a screen resulting in pure black.
Blooming
Video distortion caused by an excessive level of brightness resulting in images which are too large or exaggerated in size and are overly soft having lost a degree of focus.
BNC
(Bayonet Fitting Connector) A professional quality cable termination which is used primarily in labs and professional studios as an interconnect.
Bookshelf Speaker
A speaker of a small size, usually under 18 to 24 inches in height, which is best suited to sitting on some sort of stand be it a bookshelf, table, speaker stand or other object.
Boundary Effects
Reverberations and sound irregularities caused by sound waves bouncing off hard surfaces, namely walls, floors and ceilings.
Bridge (Bridging)
Amplification term used to describe the process whereby two channels of amplification are combined to operate as a single mono channel.
Bright
Sound quality having a harsh or brittle high-end with too much focus on the upper frequencies.
Brightness
Control or adjustment found on a video display that adjusts the black level of the image; the black level of a video display image (black level is the level of brightness or light present in the darkest or blackest portion of an image).
Butterworth Crossover
Type of crossover that uses a low-pass filter design, which results in no amplitude anomalies in the frequencies passed on by the filter (the passband).
Calibration
Setting up or otherwise getting ready a piece of electronic equipment; primarily used in regard to calibrating or properly adjusting video displays and audio equalizers.
Carousel Changer
Type of optical disc player/transport (namely CD) that holds multiple discs on a rotating platter enabling the component to play numerous discs without the user needing to manually switch discs.
Cartridge (Phono Cartridge)
Device used with record players that holds the stylus or needle and attaches to the tonearm of the record player converting signals from the record grooves into electrical energy that can be played on an audio system.
Cassette
Plastic container holding a magnetic tape, which contains audio or video signals that can be read and played back when the tape is pulled over a magnetic reader of the appropriate type.
Cassette Deck
Audio component that accepts standard audiotape cassettes from which it reads information or to which it records information.
CATV
Cable television; video and audio signals transmitted through coaxial cables terminated with F-connectors to television tuners enabling the television to display a large number of channels with little distortion and no antenna.
CD Changer
Type of compact disc player that holds more than one disc internally and that can swap discs to play various discs without the need for the user to physically swap discs or add discs.
CD-R
Form of compact disc consumers can record on using special CD "burners" or CD recorders.
CD-ROM
Compact disc read only memory; CD that cannot be written to or recorded making it useful only for data retrieval.
CEDIA (Custom Electronic Design and Installation Association)
Organization of custom audio/video installers and retailers dedicated to providing high moral standards and ethics within the audio/video community, acting as a repository for industry information, ensuring consumer satisfaction with members, promoting the audio/video industry, and ensuring top-notch quality and conduct with its members.
CEMA (Consumer Electronics Manufacturers Association)
Group of consumer electronics manufacturers dedicated to providing information on the industry, guiding legal and public policy issues in regard to consumer electronics, maintaining industry information, running the consumer electronics show, and more.
Center Channel
Third front audio channel (in addition to main stereo left and right channels) found in surround sound audio systems with the primary task of reproducing movie dialogue (what the actors are saying) thus locking the voices to the screen for all listeners.
Center Channel Speaker
Speaker used to output information from the center channel in a surround sound audio format.
Channel
Discrete, single grouping of audio information played through a sound system resulting in a steady flow of sound from one single source; for example a stereo system with two speakers has two channels, one left channel and one right channel.
Chroma
Color information in a video signal.
Chrominance
The color portion of a video signal carrying the saturation and tint (hue) information for any given point in the image.
Clipping
Amplifier distortion occurring when a high energy wave form (a very loud sound resulting in a large output) is input into an amplifier and the amplifier is unable to fully reproduce it due to power supply limitations or amplifier design limitations resulting in the audio output waves being cut off (the rounded tops sliced off resulting in short waves with flat tops).
Coaxial Cable
Specific type of cable design with two conductors, one running through the center of the cable surrounded by some form of non-conductive insulator with a second braided conductor wrapped around the insulation material and serving double-duty as a shield against interference.
Co-axial Speaker
Type of speaker driver in which a high frequency driver (a tweeter in most cases) is placed inside a low or mid frequency driver in the place of the dust cap.
Color Bars
Test pattern used to adjust the saturation and hue of video displays.
Color Temperature
Means of measuring the hue (tint or shade of color) of white light in relation to the temperature of a glowing "black body" (piece of heated carbon).
Comb Filter
Video display device that separates the chrominance (color) and luminance (brightness) portions of a composite video signal.
Compact Disc (CD)
Thin, round, reflective disc that stores digital data in the form of microscopic pits and lands and that can be read by a laser.
Component
An individual piece of equipment in an audio or audio/video system.
Component Video
Method of transferring video information using multiple, individual signals such as red, green and blue (RGB) or luminance, luminance minus blue, and luminance minus red (Y-Y/B-Y/R or Y-Pb-Pr) resulting in the highest quality signal transfer and lowest distortion.
Composite Video
Video information is carried in a single signal combining color and brightness information into the one signal.
Compression
Method for shrinking down data to fit in a smaller space than it would normally occupy.
Cone
A type of speaker driver resembling an ice cream cone, with its largest diameter at the front of the speaker enclosure becoming smaller deeper within the enclosure.
Contrast
Range of brightness between the lightest and darkest portions of an image (difference between darkest and lightest parts of a picture); also a video display control that adjusts the white level and through this increases or decreases contrast.
Convergence
The coming together on a video display of the multiple component colors which make up the display.
Crossover
The crossover splits up the frequency spectrum into pieces, which are then handed over to various speaker drivers.
Crossover Point
The frequency at which a crossover splits the audio signal.
Crosstalk
Audio distortion resulting from information in one audio channel leaking into the signal of another channel.
CRT (Cathode Ray Tube)
A large vacuum tube featuring a slightly curved glass surface at one end (the screen) and an emitter of electrons on the other, which focuses and directs a stream of electrons to hit a coating of phosphors on the back side of the screen.
Current
Flow of electricity through a circuit over a period of time; current is measured in amperes.
DAC (Digital to Analog Converter)
Electronic device that decodes digital data (ones and zeroes) into an analog waveform electrical signal that can be amplified and played by loudspeakers (or that can be used by a video display to form an image in the case of video DACs).
Damping
An audio system's ability to stop playing a signal after it has ended.
Damping Factor
The ability of an amplifier to tightly control the movement of a speaker driver and stop its movement as the signal ends (see Damping).
DAT (Digital Audiotape)
Magnetic tape cassette format used to store audio and data digitally.
Data Grade Projector
Cathode Ray Tube based video projector capable of horizontal scan rates of 31,500 Hz allowing the projector to display line doubled video and computer VGA graphics (at 640 by 480 resolution).
dB (Decibel)
Logarithmic scale measuring the intensity of sound (the sound pressure level); a 10 decibel (dB) increase represents in a doubling of sound level.
DB-25
Special form of interconnect wire commonly used to connect computers to printers but used in audio to transmit six channels of audio information over a single cable; 25 pin connection and special wire design able to transmit large amounts of line level data at a time.
DBS (Direct Broadcast Satellite)
Digital format for music and video that beams high-powered signals across North America from satellites orbiting above the equator to 18-inch satellite dishes providing a wide range of programming in a high-quality digital format.
Decorrelation
Technique used in home THX systems to create a more diffuse, full surround sound environment by splitting up the mono surround channel of matrix surround sound systems (Dolby Pro-Logic) into two channels and feeding them alternate information.
Delay
As commonly used in surround sound audio terms, the delay is the time difference between when a front speaker plays a sound and a rear or surround speaker plays a corresponding sound.
Diaphragm
The moving part of a speaker driver that generates sound through its movements which in turn create movement of air around the speaker.
Diffraction
Break-up or distortion of a sound wave created when the sound wave hits a speaker cabinet, grille cover, or other similar component of the speaker that is creating the sound.
Diffuse
Sound quality described by being hard to localize and fully filling a listening area; spread out. A diffuse sound field is one that encompasses the listener filling the listening space without being very directional (having low directivity).
Digital Audio
Method of encoding analog audio signals into digital bits of information typically using pulse code modulation resulting in high-quality signals that suffer from very little distortion and noise compared to analog signals, are easy to record and edit without degradation, are easy to transmit and record, and can be modified or adjusted quickly and without signal degradation.
Digital Surround
Sound Surround sound format in which all five channels (left front, front center, right front, right rear, left rear and an optional sixth sub-woofer channel) are discrete and full-range (the subwoofer channel is not full range), recorded in digital audio, and compressed to fit in a smaller space (see 5.1).
Digital Television
Digital video broadcast standard adopted by the FCC to replace the analog NTSC format; digital television standard composed of 18 formats including 6 high definition (HDTV) formats and 12 standard definition (SDTV) formats (see HDTV and SDTV).
Dipolar Speaker
Speaker featuring speaker drivers on two opposite sides of a speaker enclosure and wired to operate out of phase (as one driver moves in the other moves out) creating a null to the sides of the speaker (very little sound emanating to the sides) and a broad, spread-out sound in general.
Direct Radiating Speaker
Type of speaker that creates and outputs sound from only one side of the enclosure with that side aimed at the listening position.
Direct View Video Display
Video display in which the light produced by a cathode ray tube is viewed directly without first bouncing off a screen; common type of television and video monitor ranging in size from 12 inches to 40 inches (measured diagonally) having a glass screen and being fairly deep.
DirecTV
Direct broadcast satellite content provider sending out signals including the networks, most major cable channels, pay-per-view movies, sports programming and audio channels.
Discrete
Separate with no interaction between elements.
Dispersion
Describes the radiation pattern of sound waves from a sound source (the sound source being a speaker in terms of audio/video); definition of the amount of air all around a speaker excited by the sound waves it produces.
Distortion
Deviation in the output of a device from the input given; differences in a signal from input to output when the signal should retain the same characteristics from input to output.
Distribution Amplifier
An amplifier used to boost a low-level signal travelling over a long distance.
DLP (Digital Light Processing)
Digital video display technology that uses a vast array of tiny mirrors (around 500,000) that pivot on or off to reflect or not reflect red, green and blue light.
Dolby 3-Channel
A pseudo form of surround sound somewhere between stereo two-speaker operation and a full surround sound set-up with surround sound speakers in the rear; Dolby 3-channel uses the front speakers only - the front left, front center, and front right speakers.
Dolby B Noise Reduction
Reduces high frequency hiss noise by 10 decibels.
Dolby C Noise Reduction
Reduces high frequency hiss noise by 20 decibels.
Dolby Digital
Discrete digital surround sound format based on Dolby's AC-3 compression scheme to be found on DVDs, some laserdiscs and digital television (see 5.1 and AC-3).
Dolby HX Pro
Feature used when recording to a tape that extends high frequency range of cassettes and increases high frequency headroom by adjusting tape bias.
Dolby Pro-Logic
Analog surround sound format using matrix surround technology to encode four channels of audio information (left, center, right and surround) onto two channels creating a surround sound sonic environment for properly encoded movies and other programming (see Matrix Surround Sound).
Dolby Reference Level
Volume level of an audio system with the volume at the 0 decibel setting resulting in 85 decibel volume with a test tone and 105 decibel peaks.
Dot Crawl
Line of slightly but continuously moving dots found where there is a sharp color separation in a vertical line (for instance, where a bright blue rectangle meets a bright red rectangle in an image) resulting from poor chrominance/luminance filtering.
Dot Pitch
The horizontal (left to right) distance between the centers of two adjacent (next to each other) phosphor triads (grouping of one red, one green and one blue phosphor) found in a direct-view video display.
Driver
Individual moving element of a complete speaker system which is attached to the speaker enclosure and which vibrates, generally in a back and forth piston like motion, to produce sound waves when power is applied from an amplifier.
DSP (Digital Signal Processing)
Manipulation or alteration of analog signals (commonly audio or video signals) after conversion to a digital format.
DSS (Digital Satellite System)
Broadcast video and audio format that beams high-quality digital programming down to small 18-inch satellite dishes from geostationary satellites rotating around the equator (see DBS).
DTS (Digital Theater Systems)
Discrete, digital 5.1 surround sound format used for movies and music; competitor of Dolby Digital featuring similar but incompatible compression and coding technologies to place six channels of sound on a DVD or on both digital audio tracks of a laserdisc (see 5.1)
Dubbing
Recording audio or video signals from one source to create a copy recording; making a copy.
Dust Cap
Circular piece inserted into a speaker diaphragm or speaker cone near the bottom, small part of the cone (the apex) covering the voice coil.
D-VCR (Digital Video Cassette Recorder)
Audio/video playback and recording device that uses digital information on a standard VHS size tape to produce high-quality, digital video (see VCR).
DVD (Digital Versatile Disc)
Compact disc sized, 5-inch diameter optical disc capable of holding digital video and audio information for movies, music, computer games, and more.
DVI (Digital Visual Interface)
Digital video transmission standard used to connect computers and monitors and used to connect consumer electronics gear.
Dynamic Headroom
The ability of an amplifier to put out more power than its average power output for a short time in order to faithfully reproduce sudden, loud sounds without distorting or clipping (see Headroom).
Dynamic Range
Difference between the highest and lowest sound levels a sound system reproduces; also the difference between the overload level (the highest possible output) and the noise floor (point where output is at a minimum - if output goes lower it is obscured by distortions or noise making it unusable).
Dynamic Speaker
Common type of loudspeaker using traditional speaker drivers consisting of diaphragms, voice coils, stationary magnets, suspensions, spiders, and baskets in which a signal applied to the voice coil moves it and the attached speaker diaphragm in relation to the stationary magnet and basket.
Dynamics
Term used to describe how well a particular sound system can accurately portray sound from the lowest amplitude (lowest volume) signals to those of very high amplitude or volume.
Early Reflections
Sound waves bouncing or reflecting off a wall, ceiling, floor or object in a room and reaching the listener just after the direct sound waves emanating from the speakers themselves.
Electrostatic Speaker
Type of speaker that uses positive and negative electric charges over two thin panels, one stationary and one moveable, to generate sound (two positive or two negative charges repel each other while a positive and negative attract each other enabling movement and thus sound production).
Enclosure
The cabinet or structure of a speaker into which the various speaker elements (the drivers, the crossover, the binding posts, etc.) are placed and attached.
Equalization
Changing the frequency response of a given audio signal by adjusting the amplitude of the signal usually in an effort to achieve a flatter frequency response (although often misused to alter the audio signal to a more "pleasing" form which is a distortion of the intended signal - for instance, artificially adding bass for a more visceral impact).
Equalizer
An electronic device used to change the frequency response of a given audio signal; a device which provides signal equalization.
Excursion
The distance a speaker driver travels to reproduce an audio frequency.
F-Connector
A common type of cable termination used for cable television (CATV).
Feedback
Portion of the output signal routed back to the input of an electronic component at a reversed polarity and used to reduce distortion, reduce gain, or change frequency response.
Ferrofluid Cooling
Type of cooling material (ferromagnetic liquid) used primarily with tweeters to keep the driver from overheating by dissipating heat away from the voice coil.
Fiber-Optic Cable
A cable that uses light beams to transmit information rather than electrical signals traveling over metal wires.
Field
Half of an interlaced video frame containing either all the odd or all the even numbered horizontal lines.
Flat Response
A theoretical ideal for audio components, especially speakers, representing a frequency response that does not deviate from a flat line over the audible frequency spectrum when fed a flat-line test signal.
Flat-Screen Picture Tube
A direct view television screen that is generally flat.
Floorstanding Speaker
A specific type of speaker enclosure that stands directly on the floor without needing to sit on something in order to raise its speaker drivers to an acceptable height in line with the listener.
Flutter
Pitch variations heard as a fast wavering or wobbling caused by a software medium (such as an audiotape or CD) moving at varied speeds.
Flying-Erase Head
Feature of high-quality VCRs that makes transitions between recorded material smooth and clean by erasing a fraction of a second of tape just prior to the start of recording.
FM (Frequency Modulation)
Method of adding an audio signal to a carrier radio frequency (modulating the signal) so that the audio signal can be transmitted from place to place and later decoded from the radio frequency for reproduction.
Focus
Sharpness or clarity of an image.
Foot-Lambert
Measurement of luminance (brightness) equal to one lumen per square foot.
Frame
One complete screen in a video image.
Frequency
The number of repeating occurrences of a particular distinct and complete element (the positive and negative crest and trough of a single sound wave in audio) in a given time (one second).
Frequency Response
Range over which an audio component can effectively produce a useable and fairly uniform, undistorted output signal.
Front Projection Video Display
A video display using a large reflective screen and a separate projector mounted in front of the screen to project images onto the screen (as in a movie theater).
Full Power Bandwidth
The range of frequencies across which an amplifier can supply its full power rating to a speaker.
Full-Range Surround Sound Channels
A feature of 5.1 digital surround sound formats allowing discrete surround sound channels which are capable of playing across the frequency band audible to human hearing (20 Hz to 20,000 Hz).
Gain (Audio)
Increase the level of a sound by increasing the amplitude of the frequency.
Gain (Projection Screen)
The amount by which a reflective screen (or surface of some sort) reflects light hitting it.
Gauge
The size of a wire in diameter with higher gauges being smaller and lower gauges being larger.
Graphic Equalizer
Form of equalizer (device used to adjust or change a signal's frequency response typically by changing its amplitude) using multiple previously set, fixed frequency bands to adjust the amplitude of the waveform at those specific frequencies.
Graphics Grade Projector
Cathode ray tube video projector with a maximum horizontal scan rate of 63,000 Hz making it capable of displaying line quadrupled video and S-VGA graphics at resolutions of 1,024 by 1,280.
Gray Scale
Series of gray levels ranging from true white to true black.
Grille
Perforated covering that is placed over a speaker baffle to protect the speaker drivers and make the speaker more aesthetically pleasing while allowing sound waves to pass through freely.
GUI (Graphical User Interface)
Technique used to display information on a television screen or other display device in order to make the operation of some equipment easier or provide enhanced functions.
Harmonic
An additional frequency in an audio signal derived from the fundamental or original frequency as a multiple of that fundamental that is smaller in amplitude (power) than the fundamental.
HDCD (High Definition Compatible Digital)
Compact disc encoding/decoding scheme developed by Pacific Microsonics with the goal of improving on the sound of traditional CDs.
HDCP (High-Bandwidth Digital Content Protection)
Specification used to encrypt and protect digital video and audio signals transmitted between two HDCP-enabled devices using DVI or HDMI connections.
HDMI (High-Definition Multimedia Interface)
Digital video and audio connection system used to connect a variety of audio/video components, particularly high-definition video (HDTV). HDMI supports all HDTV formats along with support for up to eight channels of digital audio.
HDTV (High Definition Television)
Six ultimate quality forms of the digital television standard adopted for the United States featuring AC-3 digital surround sound, a wide aspect ratio screen (16:9), and a high-resolution picture capable of interlaced video with 1,080 horizontal lines (vertical resolution) by 1,920 vertical lines (horizontal resolution) at 24, 30 and 60 Hz refresh rate and progressive video at 720 horizontal lines by 1,280 vertical lines with refresh rates at 24, 30 and 60 Hz.
Headphone Jack
A connection on an audio or audio/video component which receives a headphone connection.
Headphones
Personal audio listening device which covers or in some way goes over or attaches to a listener's ears.
Headroom
An amplifier's ability to go beyond its rated average power for a short time in order to recreate loud or explosive audio signals that rise very quickly.
Heat Sink
A metal object, usually a row of thin metal fins, designed to dissipate heat away from electronic equipment.
High-Pass Crossover
Type of crossover that attenuates or cuts off low frequency signals and sends on only the high frequency signals falling above the crossover point (crossover frequency).
Home Theater
Term used to describe a complete audio/video system consisting of a video display, at least one video source, and surround sound (left and right front speakers and left and right rear speakers most often also having a front center speaker) designed to bring the movie theater experience into the home.
Horizontal Resolution
Quality value of a displayed image relating the number of vertical lines of information (up and down lines) used to make up an image.
Horizontal Scan Rate
The number of horizontal lines of information a video display can paint onto a screen in one second given in hertz (Hz - cycles per second).
Hue
Distinction or difference between colors ranging from red to blue.
Hz (Hertz)
Number of cycles per second, in audio commonly used in reference to sound waves.
IDTV (Improved Definition Television)
Not to be confused with digital television, improved definition television uses particular electronic means such as line doubling to improve the quality of analog NTSC video signals.
Imaging
Term used to describe the quality of a sound field put out by an audio system giving a subjective measure as to how well a system can recreate depth, width and height from the recording.
Input Sensitivity
The range of input voltages required to produce outputs from the minimum to the maximum output of an amplifier; may also refer to the input sensitivity for maximum output, which is the input in volts required for an amplifier to create its maximum power output.
Integrated Amplifier
Audio component combining the elements of an amplifier with those of a preamplifier but not containing a tuner (making an integrated amplifier different from a receiver which does contain a tuner).
Interconnect
Wire used to connect various pieces of equipment (components) in an audio/video system carrying audio or video information via low-level electric signals (not very powerful) or via light pulses (digital information carried over fiber-optic interconnects).
Interlaced
A method of displaying a video image in which all the odd lines are drawn first and then all the even lines are drawn next.
In-wall Speaker
A speaker that is installed in the wall connecting to the studs and typically using the wall as the speaker enclosure in order to create sound in a room with the minimal amount of physical presence dedicated to the speaker itself.
IR (Infrared)
Light beams just beyond the visible red portion of the spectrum that are invisible to the human eye but are used in many remote control devices to transmit information and commands.
IR Emitter
Generates infrared (IR) light beams in specific patterns in order to transmit information and commands from one device to another.
Isobaric
A type of speaker enclosure used for subwoofers and bass drivers which uses a small, sealed enclosure with two bass drivers facing each other (one inside the box facing out and the other outside the box facing in at its counterpart) and wired out of phase.
Jog/Shuttle Dial
A round dial found mainly on some VCRs and DVD players which allows the easy movement forward or backward within a software program (usually a movie).
Joule
A single unit of electrical energy equal to the energy expelled by passing one ampere of current through a one-ohm circuit (ohms measuring impedance or resistance to electric current) for one second.
Jukebox Changer
Term used to describe a CD changer that holds a large number of discs (often 50 or more) and can easily switch from one disc to another and play all the discs held within.
Jumper
Used to connect multiple speaker binding posts on speakers capable of bi- or tri-amping.
Kelvin
Temperature scale used to measure and define the color of a light source; relating to color temperature with blue being a low color temperature or cool color and red being a hot color temperature.
Keypad
In a multi-zone audio system distributed in multiple locations around a home or building, a keypad allows a person to control the volume and other aspects of audio being sent to a specific zone in which the keypad is located.
kHz (Kilohertz)
One thousand cycles per second.
Laser
A thin, highly concentrated beam of light which is used in audio to read digital media such as CDs, DVDs and laserdiscs.
Laserdisc
Large 12-inch diameter optical digital format used for playing back images and sound.
Late Reflections
Sound waves that bounce or reflect off room boundaries and objects reaching a listener a relatively long time after the direct signal from the sound source reaches the listener.
LCD (Liquid Crystal Display)
Type of video display using liquid crystals that change their light admittance (how much light they let pass through) when an electric current is applied.
Learning Remote Control
Type of remote control device that can learn commands from other remote controls.
LED (Light Emitting Diode)
Solid-state electrical device that emits random light when a forward rushing current is conducted through it.
Letterbox
Format for showing an entire movie image in its wide format on a standard 4-by-3 aspect ratio video display by fitting the image width into the width of the more square format and placing black bars above and below the image (when the wide picture is fit into a comparatively narrow space, the height of the picture does not equal that of the display).
LFE (Low Frequency Effects)
Audio channel found in 5.1 digital surround sound audio schemes (the .1) that carries only low frequency information of 80 Hz and below.
Light Valve Projector
Form of front projection device that provides vastly superior light output compared to a CRT projector with superior picture quality.
Line Conditioner
Electronic device that "cleans" the electricity coming from a wall outlet to be used by audio/video components and protects them from electric spikes and surges.
Line Doubler
Video display accessory used to enhance the picture quality of a video image by combining the two interlaced fields (grouping of all the odd or all the even lines that make up a complete image; two fields make a frame or a complete image) and progressively displaying complete frames instead of fields (displaying all the odd and even lines generated in order one, two, three, etc.).
Line Level
Term for a low-level signal sent over patch cables (interconnects) which connect various components within an audio/video system in order to transfer information but not connecting amplifiers to speakers (a high-level signal with much more power needed in order to move the speaker driver).
Line Quadrupler
Video display accessory that generates a near-HDTV image from standard NTSC video by combining the interlaced fields into progressive frames and then doubling the number of lines in those frames through a process of interpolation.
Low-Pass Crossover
Type of crossover that only allows low frequencies to pass cutting off or attenuating frequencies above the crossover point (crossover frequency).
Lucasfilm
Company started by George Lucas which, among other things, regulates and licenses THX for in-home and movie theater use.
Lumen
Measurement unit of illumination. (also known as brightness)
Luminance
The black and white portion of a video signal which carries the information for brightness and darkness and contrast.
Macro
A single command which can accomplish the same things as multiple commands.
Macrovision
A company and a technology, the technology is used widely on VCRs to make it impossible to copy VHS tapes.
Magnet
A metal which attracts iron and certain iron ores through an invisible "magnetic" force pulling or pushing those ores or electromagnets (devices with the attracting power of magnets but created by running electric current through a wire tightly wound around a piece of metal).
Masking (Projection Screen)
Masking on a projection screen used in a front projection video display refers to placing objects of some sort (usually cloth) over parts of the screen which are not needed depending on the aspect ratio of the program material being displayed.
Matrix Surround
Sound Method of encoding more than two channels of audio into a pair of analog audio channels.
MD (Minidisc)
Small digital disc format that uses perceptual coding techniques to store over an hour of CD quality sound on a two and a half inch disc contained in a square, plastic case.
MDF (Medium Density Fiberboard)
A dense construction material used to build enclosures for most speakers (especially high-end speakers).
Microphone
Device used to create an electrical signal that follows and corresponds to sound waves striking it.
Midrange
Middle band of audio frequencies typically from between 150 and 200 Hz to between 1,000 and 2,000 Hz; a speaker driver designed to operate in the middle frequencies (midrange) of the audible spectrum.
Modular
Created of multiple, independent, easily integrated component pieces that can be added or changed out easily to enhance functionality or add features.
Modulation
Modulation is a method of placing one signal on top of another by altering the base or carrier signal in a particular way that can be decoded to extract the additional, modulated signal. Modulation simply takes a baseline signal and alters it to carry the information of a second signal.
Monitor
A video display device containing no tuning mechanism.
Mono
Consisting of only one channel.
MOSFET
Type of transistor commonly used in amplifiers and other electronic circuits, the MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) places a metal conductor between two semiconducting materials (one negative n-type and one positive p-type) and generates varying levels of amplification by applying a small current to the conductor. The MOSFET works similarly to a vacuum tube (a triode tube used for amplification).
Moving-Magnet Cartridge
Method of interaction between the stylus and cartridge of a phonograph that creates electrical signals by attaching a magnet to the stylus that in turn moves up and down in relation to a coil of wire in the cartridge.
MPEG-1
Video compression format developed by the Motion Picture Experts Group using perceptual coding and predictive technologies to eliminate data from an audio/video signal and thus encode it into a smaller size.
MPEG-2
High-quality audio/video compression format developed by the Motion Picture Experts Group using perceptual coding and predictive technologies similar to MPEG-1 but including a higher bit-rate and more control over the compression and technology.
Multiscan
Video display capable of operating at multiple scan rates (namely horizontal scan rates) beyond the basic 15.75 kHz of analog NTSC video.
Mute
No sound or a cessation of all sound; a single button or control to cut off an audio signal and stop the production of sound.
Near Field
In close proximity to a speaker or speaker driver.
Noise
Typically low-level electrical distortions and interference created in an electronic component from power supply hum, interactions between internal electrical components, etc.
Noise Floor
Level at which no useful signal is produced because the signal level is below the level of noise in the system; point at which the volume or power of noise is greater than the volume or power of an intended and desired signal effectively covering up and obscuring that signal thus making it useless (see Noise).
Noise Reduction
Effort to reduce noise in a system, typically in sound reproduction equipment and sound storage media such as audiocassette tapes, through various mechanical and software based methods (see Noise).
Non-Interlaced
Also known as progressive, this term refers to the way a video image is displayed on screen where each line of a frame (one complete video image) is drawn on screen one after the other (one, two, three, four, five, and so on).
Notch Filter
Filter used to eliminate chrominance (color) information from the luminance (brightness) information in a composite video signal.
NTSC (National Television Systems Committee)
Federal government agency that established the analog color television standard used in the United States.
Octave
A doubling or halving of frequency with the bottom octave usually given as 20 to 40 Hz.
Off-Axis
Position to the side of a speaker at some angle other than 90 degrees to the front of the speaker cabinet and its speaker drivers resulting in audio signals reaching the listener as a result of the speaker's dispersion characteristics and often resulting in decreased output levels (as well as a different frequency response) compared to a position on-axis or directly in front of the speaker (see On-Axis).
Ohm
The measure of resistance in a circuit to the flow of an electric current.
Omnidirectional
In all directions simultaneously.
On-Axis
Directly in front of a speaker; position at a right angle (90-degree angle) to the front of a speaker enclosure on which the speaker drivers are located (the baffle).
Optical Cable
An interconnect cable used to transfer digital data between digital components using bursts of light carried over glass or plastic fibers (see Fiber-Optic Cable).
Oversampling
Raises the sampling rate of digital data providing a smoother signal curve, but does not provide enhanced detail or resolution of the output.
PAL
Television broadcast standard developed in England and Germany and used in many countries throughout Europe.
Pan-and-Scan
Method of fitting a widescreen aspect ratio movie onto a narrow 4-by-3 aspect ratio video display by the fitting the movie to the height of the video display and cutting off portions of its sides.
PARA (Professional Audio Retailers Association)
Professional group of audio/video retailers dedicated to ethical standards of conduct and professional advancement of the audio/video industry.
Parametric Equalizer
Type of equalizer that allows the user to adjust a signal's frequency response with complete choice over how to break up the signal and adjust it using amplitude, center frequency and bandwidth.
Passive Crossover
Crossover that does not require electricity and does not use active circuitry to accomplish its task.
Passive Radiator
Speaker driver that is not powered and is used in conjunction with a woofer generating movement by being vibrated by the back-pressure of the powered woofer.
Patch Cable
Low level cable used to transfer information in an electronic form between components in an audio/video system (see Interconnect).
PCM (Pulse Code Modulation)
Frequently used format for creating digital signals from analog signals and then recreating the analog signals with a digital-to-analog converter (see Pulse Code Modulation).
Peak Output
Maximum output (sound pressure level) in decibels a speaker can produce without distorting.
Peak Power
Amplifier power in watts available for a short time when needed to reproduce loud, sudden sounds (transients).
Phantom Center Channel
Setting available on most surround sound decoders allowing the user to eliminate the physical center channel speaker and instead create a virtual speaker by shunting the center channel output to the front left and right speakers.
Phase
Specific point in a cycle, namely a sound wave in audio, measured from a zero point and given as an angle.
Phase Adjustment
Switch or similar control device that allows a speaker's phase to be shifted or changed in order to generate sound waves that are in-phase with other sound waves (see Phase).
Phonograph
Audio component used to play back sound from a record by means of a stylus that tracks the grooves in the record and creates an electrical signal from them as the record spins at a constant speed.
Phosphor
Element that emits light (red, green and blue light as used in video displays) when it is bombarded by or excited by electrons.
Picture Tube
Common video display device that emits an electron beam onto a glass screen coated in phosphors to generate an image (see CRT).
Pink Noise
Test tone featuring equal amount of energy per octave of bandwidth.
PIP (Picture-in-Picture)
Feature found on televisions allowing one program to be viewed on the entire screen while one or more programs play in small windows superimposed over the base program.
Pit
Microscopic depression in the reflective surface of a digital optical storage medium such as a CD, DVD or laserdisc.
Pitch
Position of a tone on a scale from high to low; the frequency of vibrations creating a sound wave.
Pixel
Picture element; the smallest individual unit or piece of a video display image.
Pixelization
Distortion effect occurring in compressed digital video signals resulting in the image breaking up into large blocks instead of forming a coherent, high-quality image.
Plasma Television
A flat, shallow, light-weight television system that uses gas excited by an electric pulse to give off ultraviolet rays which in turn excite red, green and blue phosphors to generate an image.
PLUGE Pattern
Test pattern used for setting the black level (brightness at the darkest part of an image) of a video display.
Polarity
Description of an electrical circuit in which one side is positive and the other side is negative.
Port
Tube of a specified length and diameter (length and diameter dependent on specific application) with one end open to the outside of a speaker enclosure through a round hole and the other open to the inside of the speaker enclosure.
Ported Enclosure
Type of speaker enclosure which uses a port to allow air to travel from the inside of the box to the outside of the box taking full advantage of a speaker driver's output and increasing sound pressure (sound output or volume) by 2 to 3 dB compared to a similar speaker with a sealed enclosure (see Bass Reflex).
Power Rating
Maximum amount of power in watts an amplifier can put out or maximum amount of power in watts a speaker can be driven with.
Power Supply
Component of all electronic devices used to transform the electrical power supplied through a wall outlet into power the electric component can use.
Preamplifier
Audio component that adjusts the volume of an audio signal and performs switching functions between attached input devices and an amplifier or group of amplifiers.
Primary Color
One of three colors that can create all other colors through their mixture but that cannot be created by the mixture of any other colors.
Progressive Scan
Method of displaying video images in which every horizontal line is drawn on screen in a single pass one after the other to create a complete frame or single full-screen video image (see Non-Interlaced).
Pulse Code Modulation
Common form of transferring analog information into digital signals by representing analog waveforms with a stream of digital bits forming words that relate the amplitude of a signal at a certain point (the sample).
Rack Mount
Method of installing audio equipment featuring special hardware in a tall closet-like metal frame or rack.
Raster
Video image produced on a screen by a video display device that scans phosphors with an electron beam to produce the image.
RCA Connector
Type of standard, low-level signal interconnect termination or connector featuring a single, cylindrical metal rod and an outer, round metal belt.
Rear Projection Television
Television display composed of a rear projection screen, a cathode ray tube array with red, green, and blue tubes, and a series of mirrors to reflect the projected images onto the screen.
Receiver
Combination in one component of an amplifier, preamplifier and tuner.
Rectifier
Component of a power supply that converts alternating current from the transformer to direct current for use in the amplifier.
Re-EQ
Aspect of home THX processing that slightly attenuates high frequency signals in movie soundtracks when the feature is engaged.
Reflex (Bass Reflex)
Type of speaker enclosure which uses a port to allow air to travel from the inside of the box to the outside of the box taking full advantage of a speaker driver's output and increasing sound pressure (sound output or volume) by 2 to 3 dB compared to a similar speaker with a sealed enclosure (see Bass Reflex).
Refresh Rate
The vertical scan rate of a video display; number of times a video display can paint an entire screen with a video signal.
Resistance
A block to the flow of something; creating a difficulty of flow or hampering flow particularly the flow of an audio signal as a current in terms of audio/video (see Impedance).
Resolution
Number of elements used to make up or represent a signal or image with higher numbers resulting in more lifelike and accurate representations.
Resonant Frequency
Frequency at which a speaker vibrates in unison with the audio signal creating vibrations in the enclosure and driver with very little input.
Retractable Screen
Video screen used in a front projection video display to reflect images back to the viewers that can wrap itself up and out of site.
Reverberation
Reflection of sound waves against room boundaries and objects within the room persisting after the original sound has ceased.
RF (Radio Frequency)
Wide frequency range of electromagnetic signals from around 10 kHz (10,000 Hz) to 300 GHz (300,000,000,000 Hz.
RF Modulation
Method of placing an audio signal with a relatively low 20 to 20,000 Hz frequency on top of a much higher frequency radio frequency (in the area of 100,000,000 Hz) by varying the frequency of the radio signal according to the audio signal so that the audio signal can be sent over long distances and distributed through broadcast antennas (see FM).
RGB
The three additive primaries - red, green and blue - that combine to form the color spectrum (see Additive Primary).
RMS (Root Mean Square)
Generally, the average continuous power output an amplifier is capable of producing; power output an amplifier can produce consistently over extended lengths of time.
Roll-Off
Decrease in signal or sound pressure in decibels as a speaker or speaker driver attempts to reproduce frequencies outside of its primary frequency range (a midrange driver may roll-off at 500 Hz and its output decreases from that point); attenuation of frequencies outside a range specified in a crossover network (see Slope).
Room Interaction
Description of how the room or space affects the quality of sound produced through an audio system or live audio performance.
Spade Lug Connector
Type of U-shaped speaker connector attached to the ends of speaker wire and used to connect the wire to the input or output terminals (five-way binding posts) of amplifiers and speakers.
Speaker
Mechanical device used to reproduce sound waves when a power signal is applied representing those sound waves by vibrating some material that in turn creates vibrations in the air thus generating sound.
Speaker Level
High-level audio signals travelling between an amplifier and speakers having been amplified and capable of producing output from the speakers.
Speaker Wire (Speaker Cable)
Metal wire used to connect the speaker-level outputs of an amplifier to the bindings on a speaker with the job of transferring power from the amplifier to the speaker.
Spectrum
A band or range of frequencies; the audible spectrum runs from 20 Hz to 20,000 Hz (20 kHz).
Spectrum Analyzer
Electronic device that measures a particular spectrum or frequency band and displays information about that particular spectrum or band.
Spider
Component of a speaker driver that holds the voice coil and rear of the diaphragm in position near the magnet and also acts as a spring or bungee to return a moving diaphragm to its stationary position.
Spikes
Pointed objects attached to the bottom of speakers in an effort to improve the speaker's sound quality by firmly stabilizing it on the floor while also disconnecting it from the floor.
SPL Meter (Sound Pressure Level)
Device that measures the sound pressure level in a given location; commonly used in audio to properly set surround sound systems to the Dolby reference level and adjust other parameters of a sound system (see Sound Pressure Level).
Spring Connection (Guillotine Connection)
Inexpensive method of connecting speaker wires to amplifiers (particularly amplifiers integrated into receivers) and speakers using a thin sheet of metal that is pushed against bare speaker wire or a pin-type connector by a small spring.
Standing Wave
Low frequency anomaly or distortion created when a certain frequency is reproduced whose size has some special relation to the room or object it is produced in (wavelength the same size as the room dimensions) resulting in the room or object resonating with the sound and increasing the strength of the sound (the sound wave does not diminish and may instead increase as it interacts with its surroundings).
Steering
Ability of a surround sound processor to move sound around a given acoustical space from speaker to speaker.
Stereo
Two channels of audio information recorded and played back in such a way as to recreate a sound stage giving depth and breadth to audio reproduction.
Stylus
The small metal rod or shaft, also known as the needle, that reads the grooves in a record and transfers the information to the phono cartridge where an electric signal is formed to transmit the sound information (see Cartridge).
Subwoofer
Special form of speaker used to reproduce only the lower portion of the audible frequency spectrum usually from 80 Hz down to or below 20 Hz.
Surge Protection
Protection against lightning strikes and other similar sudden increases in power, which may damage electrical equipment.
Surround (Speaker Driver Surround)
Flexible rubber, plastic, foam or other material that attaches a speaker driver's diaphragm (the moving cone or dome - the drive unit) to the basket (the structure holding all the parts of the speaker driver in place) and allows the diaphragm to vibrate in and out.
Surround Channel
Specific path of audio information, the channel, provided in a surround sound audio system to drive speakers situated on the sides or rear of a room primarily providing ambience and atmosphere.
Surround Channel Speaker
Speaker used to reproduce surround channel information primarily to create ambience and sonic realism.
Suspension
The flexible element of a speaker driver that attaches the moving diaphragm to the basket and holds the diaphragm in proper relation to the rest of the speaker driver components and helping to enable the diaphragm to move and produce sound (see Surround).
S-Video
Method of transmitting video signals by separating out the chrominance (color) and luminance (brightness) portions of the video signal resulting in superior picture quality versus composite video (see Y/C).
Sweet Spot
Prime listening position for an audio system; the "best seat in the house."
S/N Ratio (Signal-to-Noise Ratio)
Maximum output of an electronic device or recording medium compared to its noise floor or level of background noise.
Sampling Rate
Number of samples or snapshots taken of a particular signal in a given amount of time (usually one second).
Satellite Speaker
A small- to medium-size speaker usually 12 to 24 inches in height designed to be placed on stands or other objects and operated with a subwoofer (see Bookshelf Speaker).
Saturation
Refers to the depth or intensity of a color on a video display based on how much white is present in proportion to the pure color creating, for example, a deep red having a high level of saturation (mostly pure red with little white) or pinkish red being lightly saturated (less pure red and a higher level of white); the amount of pure color present in an image or portion of an image.
Scan Line
A single horizontal line on a video display which, when combined with other lines on the screen, creates a complete image.
Scan Rate
Speed at which a video display device paints lines onto a screen (see Horizontal Scan Rate).
Screen Trigger
Low-voltage signal sent from a video projector to a motorized screen causing the screen to lower or roll up.
SDTV (Standard Definition Television)
Twelve standard quality forms of the digital television standard adopted for the United States featuring AC-3 digital surround sound, wide (16:9) and "square" (4:3) aspect ratios, and high-quality (though not high definition) digital video capable of interlaced and progressive scan images with 480 horizontal lines (vertical resolution) by 704 vertical lines (horizontal resolution) at 24, 30 and 60 Hz refresh rates and video capable of interlaced and progressive scan images with 480 horizontal lines by 640 vertical lines at 24, 30 and 60 Hz refresh rates.
Sealed Enclosure
Type of speaker enclosure in which the speaker driver is mounted into a sealed box with no air exchange from the air inside the box to air outside the box (see Acoustic Suspension).
SECAM
Television broadcast format, featuring 625 horizontal lines of resolution. developed in France and used in France, Russia and a variety of other countries.
Sensitivity
Measure of the sound pressure level generated at a distance of one meter from a speaker when the speaker is fed a 2.83 volt signal (1 watt at 8 ohms); efficiency of a speaker creating a certain sound pressure level from a given input with high figures representing a more efficient speaker.
Servo
Specially designed electronic circuit loop which measures speaker distortion and works with the speaker's amplifier to correct the signal in an effort to decrease distortion (see Accelerometer Servo).
Shielded
Term relating to speakers and how their magnetic fields are blocked from exiting their cabinets and interfering with video displays.
Shuffle Play (Random Play)
Feature found on multi-disc CD and DVD changers that will randomly pick a disc and play random passages (a musical track on a CD and musical track or video track on a DVD).
Sine Wave
Type of pure waveform having an equal distance from its peak to the zero or center line and from its trough to the center line and in which the positive hump and negative hump of the wave are exactly equal in length, shape and height but flipped in a mirror image about the center line.
Slew Rate
Fastest rate at which an amplifier can change the amplitude of its output signal measured in volts per microsecond with a higher figure being better (meaning that the amplifier can change more voltage in a given period of time, one microsecond).
Slope
How quickly a crossover or filter attenuates signals (decreases their power) outside its passband (those frequencies intended to pass through without attenuation); expressed in decibels per octave.
SMPTE (Society of Motion Picture and Television Engineers)
Organization dedicated to maximizing standards for video reproduction in theaters and at home, setting video standards and providing test material, disseminating information for the betterment of video/image production and reproduction, and advancing the state of the art in video technology.
Solid State
Electronic component composed of transistors and integrated circuits using no vacuum tubes.
SPL (Sound Pressure Level)
Measurement in decibels of the pressure or force exerted by a sound wave on the environment with increasing pressure generating increased loudness or higher volume (creating more pressure in the ear increases perceived loudness).
Sound Wave
Continuous audio frequency signal taking the form of a wavy line similar to waves on the water with frequency determining the length of the waves and amplitude or volume determining the height of the waves.
Soundstage
The perceived width, depth and height of recorded sound played back over an audio system; the setting similar to a theater stage from which sounds seem to emanate when reproduced through an audio system (see Imaging).
Tab-Tensioned
Projection screen format in which the screen features fabric loops or tabs running down its left and right sides connected with a wire or cable having the result of pulling the screen taught and preventing folds or creases from marring or distorting the projected image.
Tactile Sound
Sound energy converted from sound waves that vibrate the air to physical vibrations that you can feel.
Television
Video display or monitor containing its own tuner and designed to reproduce broadcast images.
Test Tone
A constant pure sine wave tone or tones played over an audio system to allow critical measurement and adjustment of an audio system both when individual components are being developed and when a complete system is being installed.
THD (Total Harmonic Distortion)
Distortion derived from the creation of harmonics (multiples of a base frequency signal) in an audio system adding additional frequency peaks to the output.
THD+N (Total Harmonic Distortion plus Noise)
Combination of total harmonic distortion (THD) with noise to achieve a complete figure representing distortions present in an electronic component with lower levels below one percent being preferable (see THD and Noise).
Three-Way Speaker
Speaker system with three or more individual drivers covering three frequency sections or bands.
THX
Set of specifications and certifications designed by Lucasfilm to ensure optimum reproduction of movie sound and video in movie theaters and home theaters (Home THX program).
THX Reference Level
Volume level designated to be used as the standard in THX certified theaters and home THX installations setting volume at 85 decibels when fed a continuous test tone and achieving 105 decibel peaks when the volume control is at the reference 0 decibel setting (0 decibels is reference on the volume control with negative numbers being the number of decibels below reference and positive number being the number of decibels above reference).
Timbre
Specific quality or unique aspect of sound that makes it distinguishable from other sounds of the same volume and frequency.
Tint
Color attribute describing a color somewhat varied from a primary color such as pink being a tint of red.
Toe-In
Angling a speaker in toward the primary listening position to achieve better imaging and sound quality.
Tone
A steady, audible frequency or steady sound. A test tone is a pure tone or a single, pure frequency sound wave.
Tone Arm
Metal shaft attached at one end to a phonograph turntable with a phonograph cartridge attached to the shaft on the other end. The tone arm holds the cartridge in relation to the record spinning on a turntable.
Toroidal Transformer
Doughnut shaped transformer commonly used in electronics and amplifiers in particular for its low noise, low resistance to current flow, and power output for its size.
Toslink
A type of fiber-optic cable connection that uses beams of light to transfer information through a clear plastic cable.
Touchscreen
Video display screen that when touched uses that touch as an input resulting in the accomplishment of some task.
Tracking
Ability of a CD player, phonograph, DVD player or other device that reads data in a continuous track around a disc to follow that information track and take information from it.
Transformer
Integral component of the power supply that pulls power from the wall outlet and transforms it or makes it into power that can be used by the electronic device (with special importance being its use in amplifiers).
Transient
Sudden, sharp signal increase often referring to a sudden increase in sound volume or power.
Transistor
Three-terminal semiconductor device that is commonly used in electronics and has the ability to amplify signals.
Transmission Line
Type of speaker enclosure in which the back-force of a bass driver (the acoustic energy generated from the backside of the driver) is routed through a fairly long, winding channel or "hall" before being ported to the outside of the cabinet.
Transparency
A subjective term used in audio to indicate how easily and how much of the sound of the live event comes through a recording when played through an audio system.
Transport
Part of an audio or audio/video playback system which reads the data from a storage medium (typically CD, DVD or laserdisc) but does not decode that data from its digital form into an analog form suitable for audio reproduction (or potentially video reproduction where applicable).
Treble
High frequency sounds.
Tuner
Electronic device used to receive electromagnetic transmissions in the form of electromagnetic waves and decode from those signals useable audio or video information that can be reproduced by an audio or video system.
Turntable
Base of a record player or phonograph on which a round platter spins (turns) with the album itself sitting atop the spinning platter.
Tweeter
High frequency speaker driver used to reproduce frequencies typically above 2,000 to 3,000 Hz all the way up to 20,000 Hz.
Two-Way Speaker
Speaker system with two or more individual drivers covering two frequency sections or bands.
Unbalanced
Wiring scheme in which one of the two necessary conductors serves an additional function as the insulation for the cable.
Universal Remote
Control Remote control that can send commands to and control features of multiple components.
Vacuum Tube
Sealed container, usually glass, with all the air taken out (creating a vacuum) and two electrodes placed at opposite ends of the container from which electrons can flow (electrons flow freely in the vacuum environment with no air present).
Variable Audio Output
Low level audio output (usually in the form of a RCA connection) which varies in strength with the volume or level of the source component.
VCR (Video Cassette Recorder)
Audio/video playback device that accepts standard analog videocassette tapes (VHS, S-VHS, Hi-8), reads the data from them, and passes along the signals to the video display and audio system.
Vent
Hole in an otherwise sealed speaker enclosure enabling air moved by the back of a speaker driver inside the enclosure to reinforce the movement of air generated outside the enclosure by the outward facing side of the speaker driver (see Port).
Vertical Resolution
Number of horizontal lines that can be output by a video display.
VHS (Video Home System)
Half-inch magnetic videotape cartridge format developed for home use with the ability to record and playback analog video and audio signals.
Video
Moving graphical images displayed on an electronic device; moving imagery recorded electronically as opposed to on film.
Video Input
Connection point or jack of a video or audio/video component that allows a video signal to enter the component from another source.
Video Output
Connection point of a video or audio/video component that allows a video signal to move out to another component.
Videophile
A person who is particularly interested in and appreciative of video.
Voice Coil
Tightly wrapped coil of wire attached to a speaker driver's diaphragm and situated in close proximity to a stationary magnet; electromagnet that generates a magnetic field when current passes through it thus being repelled or attracted by a speaker driver's magnet and creating motion.
Voltage
Electric potential between two points in a circuit that generates force to move energy through that circuit; the force pushing energy through an electric circuit.
Volume
The relative loudness or power of an audio signal resulting from the amplitude of a sound wave.
W/ch (Watts per Channel)
Measurement of power output for each channel in an amplifier.
Watt
Measurement of power derived by multiplying current by voltage; measurement used to quantify the amount of power output by an amplifier.
Wave
An audio waveform that increases in length with decreases in frequency and increases in height (amplitude) with increases in volume or power applied to it (see Sound Wave).
Wavelength
Distance between two points in the same position on a wave in two consecutive cycles (two cycles directly following one after the other).
White Level
Brightness of the lightest portions of an image (white areas).
White Noise
Test tone featuring equal amount of energy per Hz (cycle per second) of bandwidth.
Widescreen Video
Video format that shows the entire image in a movie by fitting the movie image's width into a standard analog 4-by-3 aspect ratio video display and placing black bars above and below the image (see Letterbox).
Willing Suspension of Disbelief
Term used to describe the phenomenon while watching a movie that the audience is willing to accept the movie as reality and believe the story for that time bringing the audience more fully into the story.
Woofer
Speaker driver that handles the low frequency signals of a sound wave.
Wow and Flutter
Variations in the speed of playback of a recorded signal resulting in pitch variations and distortions.
XLR
Balanced interconnect cable used to connect audio components.
Y/C - Luminance (Y) and chrominance (C)
Type of video signal transmission format that separates the color portion of the signal (chrominance) from the brightness portion of the signal (luminance) resulting in higher picture quality compared to composite video, which combines the two into a single signal.
Y-Connector
Connection that splits a single cable into two so that it may begin from one source with one connection and terminate in two connections on two components (or it may go the other way where two outputs are joined to the same input but this may not work if both outputs are sending information at the same time).
Yoke (Deflection Yoke)
Series of coils surrounding the neck or rear of a cathode ray tube that direct an electron beam to bombard particular phosphors in order to generate an image on a screen (see Deflection Yoke).
Zip Cord
Inexpensive, thin speaker wire normally 16 or 18 gauge.
Zone
In audio terms, a zone is an area in a home, office or other structure to which audio and/or video signals are distributed.
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