E
Efficiency Rating: Level of sound output measured at a prescribed distance with a standard input power. Efficiency rating standard is 1 watt (2.83V at 8 ohms) at 1 meter over a specified frequency range and is measured in decibels.

Electrostatic: One of the oldest speaker design principles, electrostatic speakers are generally comprised of two fixed perforated panels with a constant high-voltage charge applied to them. In between these two panels is an extremely low-mass diaphragm to which the audio signal is applied, causing it to move. There are variations on this construction, but all electrostatic speakers are free from the magnets and voice coils used in conventional speakers.

Enclosure: The container of air that surrounds the rear of a speaker driver.

Enhanced for 16:9: See Anamorphic.

Enhanced for Widescreen: See Anamorphic.

EQ: See Equalization or Equalizer.

Equalization: Loosely, any type of relative frequency adjustment. Specifically, the process of changing the frequency balance of an electrical signal to alter the acoustical output.

Equalizer: A component designed to alter the frequency balance of an audio signal. Equalizers may be graphic, parametric, or a combination of both.

EX: See Dolby EX.

External Crossover: A standalone unit. See crossover.

F
Feedback: The transmission of current or voltage from the output of a device back to the input, where it interacts with the input signal to modify operation of the device. Feedback is positive when it's in phase with the input and negative when it's out of phase.

Fiber Optic Cable: Glass, plastic, or hybrid fiber cable that transmits digital signals as light pulses.

FireWire: See IEEE 1394.

FM: Frequency Modulated.

Frequency: The number of cycles (vibrations) per second. In audio, audible frequencies commonly range from 20 to 20,000 cycles per second (Hz). In video, frequency is used to define the image resolution. Low-frequency video images depict large objects or images. Higher frequencies depict smaller objects (finer details).

Frequency Response: A measure of what frequencies can be reproduced and how accurately they are reproduced. A measurement of 20 to 20,000 Hz ± 3dB means those frequencies between 20 and 20,000 Hz can be reproduced no more than 3 dB above or below a reference frequency level.

Full-Range: A speaker designed to reproduce the full range (20 Hz to 20 kHz) of audio frequencies.

G
Gain: Increase in level or amplitude.

Graphic Equalizer: A type of equalizer with sliding controls that create a pattern representing a graph of the frequency-response changes. Raising sliders boosts the affected frequencies; lowering sliders cuts (attenuates) the affected frequencies.

Gray Scale: The ability for a video display to reproduce a neutral image color with a given input at various levels of intensity.

H
Hanging Dots: An artifact of composite video signals that appears as a stationary, zipper-like, horizontal border between colors.

HDCP: High-Bandwidth Digital Content Protection. Created by Intel, HDCP is used with HDTV signals over DVI and HDMI connections and on D-Theater D-VHS recordings to prevent unauthorized duplication of copywritten material.

HDR: Hard-Drive Recorder. Device that uses a computer hard drive to store compressed digital audio and video signals.

HDTV: High-Definition Television. The high-resolution subset of our DTV system. The FCC has no official definition for HDTV. The ATSC defines HDTV as a 16:9 image with twice the horizontal and vertical resolution of our existing system, accompanied by 5.1 channels of Dolby Digital audio. The CEA defines HDTV as an image with 720 progressive or 1080 interlaced active (top to bottom) scan lines. 1280:720p and 1920:1080i are typically accepted as high-definition scan rates.

Hi-Fi Stereo: Feature found on VCRs that records or plays back stereo soundtracks with improved fidelity compared to using the linear stereo tracks.

High Gain Screen: Material that reflects more light than a reference material. Increases a projector's light output at the expense of uniformity.

High Pass: A filter that passes high frequencies, and attenuates low frequencies. Same as low cut.

Home Theater in a Box: A complete home theater system in one box (or at least sold together as a package). Consists of five or more speakers, a subwoofer, and a receiver. May also include a DVD player.

Horn: A type of speaker that looks like a horn. These speakers have small drivers and very large mouths; the horn shape serves to transform the small radiating area of the driver into the much larger radiating area of the mouth of the horn.

Hz: Hertz or cycles per second. Something that repeats a cycle once each second moves at a rate of 1 Hz.

IEEE 1394: Networking standard for PCs. Combined with 5C copy protection, is used as a two-way connection to transfer the MPEG-compressed digital bitstreams between consumer electronics items, including HDTV tuners and displays, D-VHS recorders, DVD players, and DBS receivers. Also called FireWire, iLink, É

iLink: See IEEE 1394.

Integrated Amplifier: A combination preamp and amplifier.

Interconnects: Any cable or wire running between two pieces of A/V equipment. For example, RCA terminated cables connecting pre/pros and amps.

Interlace: Process of alternating scan lines to create a complete image. In CRT displays, every second field/frame is scanned between the first field/frame. The first field represents the odd lines; the second field represents the even lines. The fields are aligned and timed so that, with a still image, the human eye blurs the two fields together and sees them as one. Interlace scanning allows only half the lines to be transmitted and presented at any given moment. A 1080i HD signal transmits and displays only 540 lines per 60th of a second. 480i NTSC transmits and displays only 240 lines per 60th of a second. Motion in the image can make the fields noticeable. Interlaced images have motion artifacts when two fields don't match to create the complete frame, often most noticeable in film-based material.

Inverted Dome: A type of speaker-driver shape; usually used for tweeters (concave).

Imaging: The ability to localize the individual sound sources in three-dimensional space.

Impedance: A measure of the impediment to the flow of alternating current, measured in ohms at a given frequency. Larger numbers mean higher resistance to current flow.

Isobarik: Also known as compound loading. By using two low frequency drivers (generally mounted face-to-face and wired electrically out-of-phase or mounted front-to-back in a shallow tube and wired electrically in phase) you can halve the volume of the cabinet without reducing the low frequency extension of the subwoofer.

K
Keystone: A form of video image distortion in which the top of the picture is wider than the bottom, or the left is taller than the right, or vice versa. The image is shaped like a trapezoid rather than a rectangle.

kHz: Kilohertz or one thousand Hz.