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Audio and Video Glossary

Here is a Glossary can help you understand some of the terminology used in Audio and Video.

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Acoustics - The science or scientific study of sound. The properties of a room or environment that affect the qualities of sound.

Airy - Spacious or Open. Instruments sound like they are surrounded by a large reflective space full of air. Good reproduction of high-frequency reflections. High-frequency response extends to 15 to 20 kHz.

Ambient Noise Level - “Background” noise from any source that affects the listener’s ability to hear what is produced by a sound system.

Amplifier or Amp - An electronic device that increases the voltage, current, or power of a signal. A combination speaker/amplifier designed for use with an instrument, as in a guitar amp or keyboard amp.

Auxiliary Jack - A socket for plugging in an audio source, such as an MP3 Player, iPod, or any portable audio source. Also called a media jack or audio jack. Found on many types of audio equipment and musical instruments that accept external sound sources.



Bass - The lower end of the frequency range, from about 20 Hz to about 300 Hz.

Bassy - Emphasized low frequencies below about 200 Hz.

BNC Connector - A miniature quick connect or disconnect coaxial RF connector used for coaxial cable. BNCs are ideally suited for cable termination for miniature-to-subminiature coaxial cable. Used with radio, television, and other radio-frequency electronic equipment, test instruments, and video signals.

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Cardioid Microphone - A unidirectional microphone with a cardioid or “heart” shaped pattern of sensitivity that reduces pickup from the sides and back. Commonly used as vocal or speech microphones since they are good at rejecting sounds from other directions.

CAT-5 Cable - A nickname for a cable with four wire pairs that each meet the “Category 5” specification for data communications. Consists of either “solid” (24 gauge wire) cores for in-wall wiring or “stranded” (several thin wires) cores for patch cables that connect wall jacks to equipment. Consists of “shielded” or “unshielded” cabling.

Clipping - Audible distortion that occurs when a signal’s level exceeds the limits of a particular circuit. When an amp or preamp is driven beyond its output ability, and begins to distort, it is said to be clipping.

Coaxial Cable or Coax Cable - A cable that has an inner conductor surrounded by a flexible, tubular insulating layer, that is surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing a geometric axis. Coaxial cable differs from other shielded cable used for carrying lower-frequency signals, such as audio signals, in that the dimensions of the cable are controlled to give a precise, constant conductor spacing, which is needed for it to function efficiently as a radio frequency transmission line.

Coaxial RF Connector - An electrical connector designed to work at radio frequencies in the multi-megahertz range. RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers.

Component Video - A video signal that has been split into two or more component channels.

Composite Video - The format of an analog television (picture only) signal before it is combined with a sound signal and modulated onto an RF (radio-frequency) carrier. A picture signal combined with synchronization and color information.

Compressor - A device that reduces or compresses a signal’s dynamic range. The threshold is the level that sets the point above which compression takes place. Compression allows for a more even signal level, avoiding any moments too loud or too quiet for the listeners.

Condenser Microphone - A microphone that depends on an external power supply or battery to electrostatically charge its condenser plates. Produces a high-quality audio signal.

Console or Mixing Console - An audio mixer. Used in live performances and recording studios. Combines signals from multiple audio sources.

Corded or Wired Microphone - A microphone that is physically connected by a cable to a sound system.

Crossover or Electronic Crossover - An electronic device or circuit that, when inserted between a mixer and amplifier, divides the audio spectrum into individual frequency ranges (low, high, and/or mid) before sending them to specialized amplifier/speaker combinations. An advantage of this type of crossover is that it increases efficiency.

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Decibel or dB - A relative unit of measure between two sound or audio signal levels. As a measure of sound pressure levels, used to indicate loudness.

Directional Microphone - A microphone that is designed to receive sound from a particular direction. Cardioid mics are an example. They pick up well from the front, slightly less from the sides and very little from the rear. This is by design, so as long as you keep the back of the microphone aimmed at any nearby loudspeakers, you'll be able to get more gain before feedback becomes a problem.

Directivity - A figure of merit for an antenna.

Distortion - Any discrepancy between the source material and the sonic output of a sound system.

Driver- An electronic to acoustic transducer, converts electric energy into sound waves. Woofers, mid-range, and tweeters are drivers.

DVI or Digital Visual Interface - Is a video display interface connector used to connect a video source, such as a display controller to a display device, such as a computer monitor. Used as an industry standard for the transfer of digital video content. The interface is used to transmit uncompressed digital video and can be configured to support DVI-D or digital only, DVI-A or analog only, and DVI-I or digital and analog.

Dynamic Microphone - A microphone that converts sound into electrical pulses by means of a moving electromagnetic coil.

Dynamic Range - Describes the range between the softest to the loudest sound levels. Also describes the range between the noise floor and maximum sound output of a sound system or audio component.



End Address A microphone that picks up sound from its end. Aim the end of the microphone towards the sound source.

Equalization or EQ - The electronic manipulation of specific frequencies. Bass and treble controls are an example of a two-band EQ circuit. More elaborate EQs will have more bands and some even have adjustable frequencies and bandwidth.

Equalizer or EQ - A device that permits the precise control of specific frequency ranges.



Faders - Slide controls on an audio mixer used to adjust the mix between multiple audio sources.

Feedback - A sustained squeal, shriek, or howling sound or tone created when sound from a speaker is picked up by a microphone and then fed back into the sound system. A self-perpetuating cycle which can be stopped by decreasing the volume. Caused by a regeneration of sound leaving a speaker and entering a microphone.

Foldback - See Monitor.

Frequency - The number of sound waves that pass a given point in one second. The determiner of pitch.

Full-Range Loudspeaker - A speaker designed to reproduce most of the audible range of human hearing, as opposed to a Subwoofer which only reproduces low frequencies.



Gain - Degree of signal amplification achieved in an amplifier circuit. Expressed in dB.

Gain Before Feedback- The amount of volume that may be achieved before acoustical feedback occurs.

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Handheld Transmitter

HDMI or High Definition Multimedia Interface - A digital replacement for analog video standards. An audio and video interface connector for transferring uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, to a compatible computer monitor, video projector, digital television, or digital audio device.

Headroom - The difference between the available power versus the required power. Too small of a margin risks clipping and damage to loudspeakers

Hertz or Hz - Unit of frequency, equal to one cycle per second. It is used in the measurement of radio, sound, and other waves.

Horn - An acoustical transformer which, when coupled to a driver, provides directivity and increases the driver’s loudness.

Hum - Unwanted low frequency tone. Usually caused by 50 Hz or 60 Hz AC (alternating current) and its harmonics.



Intermodulation or I.M. Distortion - When two different frequencies are simultaneously passed through an amplifier or another audio component. Expressed as a percentage of total signal intensity. I.M. Distortion is known to cause listener fatigue.



Jack - A female input or output connector, usually for a microphone or an instrument.



Kilohertz or kHz - A unit of frequency equal to 1,000 hertz or Hz.

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Limiter - A device that electronically controls or “limits” the peak levels of program material.

Line Level - Audio signal levels. +4dBu (professional audio equipment i.e. mixer outputs and amplifier inputs) or -10 dBV (consumer audio equipment, i.e. CD players and tape recorders).

Line Output Jack or Audio Out Jack - An analog electrical signal for connection between audio devices. A jack found on computers that allows external speakers, headphones, or other output devices to be connected to the computer, which enables computer generated audio to be heard.



Microphone - A device for converting sound waves into electrical energy.

Mic Level - Signal level coming directly out of a microphone, very low (in microvolts), requires preamplifier to boost signal level to Line Level.

Microphone Processor - A device that, when installed between a microphone and an amplifier or preamp, allows the manipulation of the signal originating at the microphone.

Mid-Range - A speaker driver that reproduces sound in a the frequency range from approximately 300 to 5000 Hz. Once called a squawker.

Mixer - An electronic device that permits the combining of a number of audio inputs into one or more outputs. Mixers commonly provide a variety of controls for tone, volume, balance, and effects for each “channel”.

Monitor - A loudspeaker or earphone dedicated to making it possible for a performer to hear or monitor their own performance.

Monitor Jack - A jack used to access communications circuits to observe signal conditions without interrupting the services.

Muddy - Not clear. Weak harmonics, smeared time response. I.M. distortion.

Muffled - Sounds like it is covered with a blanket. Weak high sounds or weak upper midlevel sounds.

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Noise Reduction - Automatic circuitry that reduces noise.


Ohm or Ω -The basic unit of the measurement of resistance

Ohm’s Law - A law stating that electric current is proportional to voltage and inversely proportional to resistance.

Omnidirectional Microphone - A microphone capable of picking-up sound or radiating sound equally from all directions.



PA - Abbreviation of “public address” system. One or more speakers connected to amplifier. May include a mixer and any combination of sound reinforcement devices.

Patch Cable or Cord - A short electrical cable used to connect individual components of a sound system. A cable that connects a wall jack to audio or video equipment.

Phantom Power - Operating voltage supplied to a condenser microphone by a mixer or external power source.

Pitch - Tone. A function of frequency.

Power Amplifier - An electronic device that increases the volume of a signal. A basic unit for of all sound systems to provide sound reinforcement. Power amplifiers are typically connected to a preamp which provides controls for individual functions; such as, level and tone.

Powered Mixer - A mixer and an amplifier in one unit.

Powered Speakers - A speaker with a built-in amplifier. Also known as a powered monitor, self-powered speaker, or active speaker. Can be connected directly to a mixing console or another low-level audio signal source without the need of an external amplifier.

Preamplifier or Preamp - An electronic device that amplifies a very weak signal. Used to match an input signal from a microphone or guitar pickup to the input of a power amplifier and transmits it to a main amplifier.

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Radio Frequency Interference or RFI - Radio signals from external sources that invade, and can be heard through sound systems; such as cell phones, two-way radios, and pagers.

RCA Connector - Sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals. The connection's plug is called an RCA plug or phono plug, for "phonograph". RCA plugs for composite video are yellow and RCA plugs for stereo audio are white and red.

Receiver - See Wireless Reciever

Reverberation - Sound waves that continue to bounce around a space after the sound source has ended.



Side Address - A microphone that picks up from the side. Aim the side of the micophone towards the sound source

S-Video or Separate Video - Analog video connection in which the black and white portion and color portion of the signal are transferred separately. The signal is then recombined by the television or video recording device at the receiving end. The result is less color bleeding and more defined edges. Transmits luminance and color portions separately, using multiple wires.

SPL or Sound Pressure Level - The measured value of the variation in air pressure due to a sound wave. 0 dB is the threshold of hearing, 140 dB is irreparable hearing damage.

Snake or Audio Snake - A cable, often running between the stage and control board, that combines multiple lines; used to connect microphones, instruments, and monitors to a mixer.

Speakon Connector - A type of cable connector mostly used in professional audio systems for connecting speakers to amplifiers via a speaker cable. The connectors lock into sockets with a twisting motion making them less prone to disconnection than a standard TRS plug. The connectors are fully shielded from human touch, preventing electrical shock risks associated with audio amplifiers and unshielded connections.

Stage Box - A rugged metal housing with XLR and TRS connectors used to connect microphones and other sound equipment to the audio snakes. Allows the control board to be situated further away from the stage.

Stage Monitor - See Monitor.

Subwoofer - A loudspeaker that is designed to reproduce low frequencies, typically 40 to 150 Hz.

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Threshold - The signal level that a compressor, limiter or expander circuit will start working.

Transducer - A device which converts sound into electrical energy ( a microphone), or electrical energy into sound (a speaker).

TRS Connector - A tip, ring, or sleeve connector typically used for analog and audio signals. Cylindrical in shape, typically with three contacts. Can be designed with two contacts for a TS connector and three contacts for a TRS connector. Also referred to as audio jack, phone jack, phone plug, or jack plug. Specific models are termed stereo plug, mini-jack, mini-stereo, headphone jack, tiny telephone connector, and bantam plug.

Transmitter - See Wireless Transmitter

Tweeter - A speaker or driver that reproduces only frequencies above a certain range, usually about 3 kHz. A speaker designed to reproduce high frequencies.



Unidirectional Microphone - A microphone that picks-up or is sensitive to sound primarily from one direction.





Wireless Microphone - A microphone without a physical cable connecting it directly to the sound system. Converts audio signals created by microphones into radio signals, which are sent by a transmitter through the air to a receiver.

Wireless Receiver - Recovers the audio from the transmitter via antenna. Mounted in or located in the sound system. The other audio equipment is connected to the receiver unit by cable.

Wireless Transmitter - Battery-powered radio transmitter in the microphone body, which transmits the audio signal from the microphone by radio waves to a nearby receiver unit, which recovers the audio.

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XLR Connector - A three pin connector, circular in design. Widely used in the audio industry for a balanced audio interconnection or digital audio. Can also be used for video, stage lighting equipment, and low voltage power supplies.





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