Home Theater Glossary
Absorption
The use of soft or fibrous materials to reduce acoustical energy and prevent sound reflection.
AM
The abbreviation for Amplitude Modulated.
Amplifier
A component used to improve an audio signal’s level.
Aspect Ratio
The width-to-height ratio of on-screen images.
ATSC
Acronym for the Advanced Television Systems Committee.
Attenuate
To lower the level or strength of a signal.
Bass
Low sound frequencies that register below 200Hz
Bass Trap
A device or structure used to improve the acoustics of a room by absorbing excessive bass frequencies. Bass traps are helpful in decreasing the “muddy” or “booming” sounds that can distort home theater audio.
Black Level
In video, the term black level refers to the brightness of (or amount of light emitted by) the black or darkened portions of onscreen images.
Brightness
The light level of a video image.
Cathode Ray Tube
The original television technology, which uses a cathode ray to deposit electrons onto a phosphorescent screen, forming the onscreen image.
CD
The abbreviation for Compact Disc.
CD-R
The abbreviation for Recordable Compact Disc.
CD-RW
The abbreviation for Rewritable Compact Disc.
CEA
The Consumer Electronics Assciation.
Center Channel
In home theater audio, the type of speaker that provides voice and multi-channel effects. This speaker is named for where it’s typically placed in home theater setups: front and center.
Channel
In the electronics industry, a channel is an individual signal path.
Component Video
A video signal that transmits luminance and color via 3 separate 75-ohm channels.
Composite Video
A type of video signal that is able to transmit both luminance and chrominance (color) over a single 75-ohm channel.
Contrast
The difference in brightness that occurs between the darkest and brightest areas in an image.
Damping
The mechanical control of acoustic vibrations.
Damping Material
A substance or material that is used to absorb sound waves and convert them into a different form of energy.
DBS
The abbreviation for Direct Broadcast Satellite.
Delay
The amount of time it takes for a “sonic event” to be perceived by a listener.
Diffusion
The spreading-out of light or sound waves.
Digital Audio Server
A type of hard drive that has the ability to store and play back compressed audio files.
Dipole
Often recommended for surround-sound effects, dipole speakers are designed with drivers mounted on opposite faces.
DNR
The abbreviation for dynamic noise reduction, a type of technology that uses a circuit to process signals, which then cuts down on high-frequency noise.
Dolby Digital
A digital encoding system that allows up to 5.1 discreet audio channels to be compressed into a single stream of data.
Dome
Refers to a convex shape that is often used for tweeters (high frequency speaker-drivers).
Driver
The active part of a speaker, without an enclosure.
DSP
The abbreviation for Digital Signal Processing, the digital manipulation of an audio signal to produce different effects.
D-VHS
The abbreviation for Digital Video Home System, a technology that uses magnetic tape to record digital (rather than analog) signals.
DVD
The abbreviation for Digital Video Disc.
DVD-R
The abbreviation for Digital Video Disc – Recordable.
DVD-RW
The abbreviation for Digital Video Disc – Rewritable.
DVI
The abbreviation for Digital Visual Interface, a standard for connecting computers to digital displays.
Dynamic Range
The span between a system’s highest and lowest levels. In audio, dynamic range is indicated in decibels, and in video it’s usually referred to as the contrast ratio.
Equalization
The adjustment of a frequency’s balance, to change the overall sound of an audio system.
Feedback
The doubling-back of a current from a device’s output to its input, which causes a reaction that can either positively or negatively affect the device’s operation.
FM
The abbreviation for Frequency Modulated.
Frequency
The number of vibrations (or cycles) that occur each second.
Frequency Response
A measurement that indicates whether or not – and how accurately – a signal can be reproduced.
Full-Range
A type of speaker that is capable of reproducing a full range of audio frequencies (from 20Hz to 20kHz).
Gain
An increase in amplitude.
Graphic Equalizer
An equalizer that uses sliding controls to indicate changes in frequency-response.
Gray Scale
A graduated color scale ranging from white to black, with graduated shades of gray in between. Used to calibrate the black levels of home theater screens.
HDMI
Abbreviation for High Definition Multimedia Interface, a connection format for high definition television.
HDR
The abbreviation for Hard Drive Recorder.
HDTV
The abbreviation for High Definition Television.
Home Theater in a Box
A “package deal” home theater system consisting of a receiver, a subwoofer, 5 speakers and often a DVD player.
Home Theater Receiver
An electronic component that acts as a central hub for most or all of a home theater’s devices. A home theater receiver provides both input and output ports for the connection of your system’s equipment, and typically integrates the functions of a preamp, a radio tuner and a multi-channel amplifier combined.
Horn
A speaker with a small driver and a large mouth; called a “horn” because it looks like one.
Hz
The abbreviation for Hertz, or number of cycles per second.
kHz
The abbreviation for Kilohertz (which is equal to 1000Hz).
LCD
The abbreviation for Liquid Crystal Display, a type of screen that streams light through liquid crystal-filled cells to form images.
LCOS
The abbreviation for Liquid Crystal on Silicon, a type of micro-display technology used to produce ultra high-resolution images in some projection TVs.
LFE
The abbreviation for Low Frequency Effects, a type of low frequency audio often found in the soundtracks of DVD movies. LFEs can only be detected if they are reproduced through a home theater subwoofer.
Megachanger
A CD or DVD player that has the capability to hold 50 or more discs.
MHz
The abbreviation for Megahertz (equal to one million Hz).
Midbass
Just like it sounds, this is the term for middle bass frequencies that range anywhere from 50Hz to 100Hz
Midrange
Sound that falls within the middle segment of the audio frequency range.
Mono
An abbreviation for Monophonic Sound (single-channel audio).
MP3
A widely used name for MPEG-1 Audio Layer-3, the technology that allows compressed-format audio files to be sent over the Internet.
Multiroom
A single-source audio/video system that provides signal to multiple areas of a home or building simultaneously.
Multizone
See Multiroom.
Noise
Signal interference.
NTSC
Abbreviation for the National Television Standards Committee.
Optical Digital Cable
A type of fiber optic cabling used to transmit digital audio signals from one point to another in the form of light pulses.
Pixel
The smallest, most basic unit of data in a video image.
Plasma
A type of flat-screen technology that uses charged xenon- and neon-filled cells to create images.
Preamplifier
An electronic component that is used to connect all of a home theater’s devices, as well as to send output signals to a Power Amplifier.
Projection System
A type of video display system, in which images are projected onto a screen.
Pulse Code Modulation
The digital audio formatting technology used to convert sound into binary information.
Rear-Projection Television
A type of video display in which an image is reflected off a mirror or chip, then projected onto the backside of a screen.
Receiver
An electronic device that receives broadcast signals.
RF Modulator
The abbreviated form of radio frequency modulator, a device that converts output signals from video devices (like DVD players and game systems) into TV-compatible input signals.
RGB
The abbreviation for Red, Green and Blue, the three main color elements used to make up any image viewed on a display screen.
SDTV
The abbreviation for Standard Definition Television.
Signal-to-Noise Ratio
A signal to noise level comparison, used to measure the clarity of a signal.
Sound Field
The overall acoustics of a given space.
Subwoofer
A type of speaker used to deliver bass frequencies of 80Hz or less.
Tactile Transducer
A device that implements home theater audio by transmitting ultra-low bass frequencies in such a way that the sound waves are felt but not heard. Tactile transducers are typically mounted beneath home theater seating, and transfer vibrations directly into the furniture, so that anyone viewing a movie will not only see and hear the film, but will be able to feel it as well.
TIVO
A recording technology that allows paid subscribers to selectively (and automatically) record onto a hard drive, instead of onto a tape or disc.
TOSLINK
The shortened form of ToshibaLink, a Toshiba-developed technology that is used to transmit digital audio signals over fiber optic cable. Also known as a Digital Optical Connection.
Transducer
A device that is able to convert one type of energy into a different energy form.
Tweeter
A type of speaker driver that can deliver high sound frequencies in the range of 5,000 – 10,000Hz.
Universal Remote
A remote control that can be programmed to operate multiple home theater components, often simultaneously.
Viewing Angle
The maximum angle at which a screen can be viewed while still maintaining an acceptable level of picture definition.
WMA
The abbreviation for Windows Media Audio, an audio compression format developed by Microsoft.
Woofer
A low frequency speaker driver.
Zone
The room or rooms in a home that are fed by the same (single) audio or video source.