Audio Visual Glossary
Audio Visual Glossary
Written By: Kate Couch and Tony Sprando
Whether you’re new to the audio-visual world or an old pro, a glossary of words to help you understand what we’re referencing in our articles and communications with you is a helpful tool. Below is some common audio-visual lingo with its proper definitions. It’s broken up into different categories, video, audio, av it, lighting, and general.
ANSI – American National Standards Institute. Where does it apply? ANSI, lumens in relation to a projector the brightness of a projector.
DLP – Digital Light Processing(c) by Texas Instruments. A projection system that has technology based on the Digital Micromirror Device (DMD). It uses thousands of microscopic mirrors on a chip focused through an optical system to display images on the screen.
Front screen projection – a system that employs a light-reflecting screen for use when the image will be projected from a source in front of the screen.
LCD – Liquid Crystal Display.
LCoS – Liquid Crystal on Silicon
LED – Light Emitting Diode.
Viewing angle – the viewing angle determines how far off the axis (screen centerline) a viewer can still sit and still see a quality image. This is no greater than 45 degrees off the projection axis.
Zoom lens – lenses that allow the operator to adjust the focal length for sizing or distance.
Lumen – a measure of the light quantity emitted from a constant light source across one square meter.
Matte white screen – evenly disperses light 240 degrees uniformly, both horizontally and vertically, creating a wide viewing cone and wide viewing angle. Below is a common site for buying screens
Codec– There are two kinds, soft codec, which would be google hang out, web x, or zoom they live on my butt or are “butt-based.” Conference or hardware codec would be a conference call hosted by the person indicating the call, poli-cons.
native resolution – The number of rows of horizontal and vertical pixels that create the picture. The native resolution describes the actual resolution of the imaging device and not the resolution of the delivery signal.
Nit – the metric unit for the screen, or surface brightness.
Pixel – an acronym for picture element. The small element used to build a digital image.
Ratio – the comparison of two quantities. Aspect ratio 16:10 16:9 4:3
Rear screen projection – a presentation system in which the image is projected through a translucent screen toward the audience; projecting an image through a translucent screen material for viewing from the opposite side, as opposed to front projection.
Resolution – 1. the amount of detail in an image. 2. the number of picture elements (pixels) in a display.
Scaler – feature in a display device that changes the size of an image without changing its shape. Scaling may be required when the image size does not fit the display device.
Throw distance – the length of the projection beam necessary for a particular projector to produce an image of a specified size. It’s common to use a throw distance calculator like the one linked below https://www.projectorcentral.com/projection-calculator-pro.cfm
Mixer – a device for blending multiple audio sources.
Bi-directional polar pattern – the shape of the region where some microphones will be most sensitive to sound from the front and rear while rejecting sound from the top, bottom, and sides.
Boundary microphone – a microphone that relies on reflected sound from a surrounding surface.
Cardioid – a heart-shaped region where some microphones will be most sensitive to sound predominately from the front of the microphone diaphragm and reject sound coming from the sides and rear.
SPL– Sound pressure level. Sound pressure or acoustic pressure is the local pressure deviation from the ambient atmospheric pressure, caused by a sound wave. In the air, sound pressure can be measured using a microphone, and in water with a hydrophone. The SI unit of sound pressure is the pascal. See more here, https://www.youtube.com/watch?v=OSRwM2yy3co
Delay– an audio signal processing device or circuit used to retard the speed of transmission on one or more audio signals or frequencies.
Dynamic microphone – a pressure-sensitive microphone of moving coil design that transduces sound into electricity using electromagnetic principles. Linked is the Shure SM58 one of the most popular dynamic microphones on the market today. Shop
Echo cancellation – a means of eliminating echo from an audio path. Learn more from this website below https://wiki.analog.com/resources/tools-software/sigmastudio/toolbox/adialgorithms/aec
Feedback – 1. unwanted noise caused by the loop of an audio system’s output back to its input. 2. in a control system, data supplied to give an indication of status, i.e., on or off.
Gain – 1. electronic signal amplification. 2. the ability of a projection screen to concentrate light. + gain b4 feedback
Lavalier – a small microphone designed to be worn either around the neck or clipped to apparel.
Midrange – loudspeakers that reproduce midrange frequencies, typically 300 Hz – 8,000 Hz. high mid and low
Mixer – a device for blending multiple audio sources.
Monophonic – uses input from all microphones and relays them from the electronic control system to the loudspeakers using a single path or channel.
Notch filter – “notches out,” or eliminates, a specific band of frequencies.
Omnidirectional – describes the shape of the area for microphones that have equal sensitivity to sound from nearly all directions. Like the SM58 as well as a directional microphone
Phantom power – a direct current (DC) power source available in various voltages. Commonly found on audio mixers and interfaces required by most condenser microphones.
Point-source – a sound system that has a central location for the loudspeaker(s), mounted high above, intended to cover a large area; typical of a performance venue or a large house of worship.
Shotgun microphone – a long, cylindrical, highly sensitive, unidirectional microphone used to pick up sound from a great distance.
Speakon(c) – specialized connector used to hook up speakers without causing a short circuit; allows connection of speaker while working, or hot.
Array speakers – Or line array, A-line array is a loudspeaker system that is made up of a number of usually identical loudspeaker elements mounted in a line and fed in phase, to create a near-line source of the sound. A vertical line array displays a normally wide horizontal pattern useful for supplying sound to the majority of a concert audience. They are usually curved and have stacks of rectangular-shaped speakers.
Polar pattern – (or pickup pattern); the shape of the area that a microphone will be most sensitive to sound.
Radiofrequency (RF) – generally refers to signals such as radio and TV broadcast signals, or radiofrequency control signals; the range of frequencies used for electrical transmission.
Radiofrequency interference (RFI) – the tendency of a radio transmission to interfere with other electronic signals. Radiofrequency energy is radiated by all electrical equipment – when it is a strong enough signal it becomes interference in audio systems.
Subwoofers – loudspeakers that reproduce lower frequencies, typically 20 Hz – 200 Hz.
Super-Cardioid Polar Pattern – the exaggerated heart-shape of the area that a highly directional microphone is most sensitive to sound.
Boundary Microphone– placed on a table to pick up sound. Used in boardrooms and other environments where a number of talkers must be “picked up” and where the microphone needs to remain unobtrusive. It uses the table to increase the pick-up. “Preferable wood sources”
TRS – Tip, Ring, Sleeve – a three-conductor design of a phone connector that can be terminated as balanced or unbalanced.
TS – Tip, Sleeve – a two-conductor design of a phone connector used for an unbalanced circuit.
Unbalanced circuit – transmits the audio signal on a single conductor that is referenced to the ground. +balence circuit
Woofers – loudspeakers that have low frequencies, typically 20 Hz – 200 Hz.
Footcandle – abbreviated as Ftc, it is an English unit of measure expressing the intensity of light illuminating an object. The illumination from one candle falling on a surface of 1 square foot at a distance of 1 foot.
Lux – a contraction of the words luminance and flux; metric version of footcandle.
Diffusion – The scattering or random redistribution of a sound wave from a surface. It occurs when surfaces are at least as long as the sound wavelengths, but not more than four times as long.
Ambient noise – a sound that is extraneous to the intended, desired, intentional, audio; background noise.
Direct sound – also known as near-field, is a sound that is not colored by room reflections.
Distributed sound – a sound system in multiple loudspeakers separated by distance and typically operates in a lower sound pressure level than a high-pressure system. The loudspeakers are most often suspended over the heads of the listeners.
Distribution amplifier – an active device used to split one input into multiple outputs while keeping each output isolated, and the signal level constant.
Early reflected sound – created by sound waves which are reflected (bounced) off surfaces between the source and the listener. The sound waves arrive at the listener’s ear closely on the heels of the direct sound wave
Fundamental frequency – the lowest frequency in a harmonic series; known as “pure tone.” White noise- white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. Used for sleep and in healthcare.
Pink noise– Pink noise or ¹⁄f noise is a signal or process with a frequency spectrum such that the power spectral density is inversely proportional to the frequency of the signal. In pink noise, each octave interval carries an equal amount of noise energy. Pink noise is one of the most common signals in biological systems.
Brown noise– In science, Brownian noise, also known as Brown noise or red noise, is the kind of signal noise produced by Brownian motion, hence its alternative name of random walk noise.
Below is a link that explains the science of white pink and brown noise. https://www.soundofsleep.com/white-pink-brown-noise-whats-difference/
Near-field – A sound that has not been colored by room reflections. This is also known as the direct sound.
Reflection – light or sound energy that has been redirected by a surface.
WLAN – Wireless Local Area Network; a network that shares information by radio frequency (RF).
Twisted pair – any number of wires that are paired together and twisted around each other; can be shielded or unshielded.
Cats are sets of cables with each one getting more durable to read about the difference between all of them see this article. https://www.loxone.com/enus/blog/cat7-cable/
Category 5 (Cat 5) – the designation for 100-ohm unshielded twisted-pair cables and associated connecting hardware whose characteristics are specified for data transmission up to 100 Mb/s. (Part of the EIA/TIA 568A standard.)
Category 5e (Cat 5e) – an enhanced version of the Cat-5 cable standard that adds specifications for far-end crosstalk. (Part of the EIA/TIA 568A standard.)
Category 6 (Cat 6) – cable standard for Gigabit Ethernet and other interconnect that is backward compatible with Category 5 cable, Cat-5e, and Cat-3. Cat-6 features more stringent specifications for crosstalk and system noise. (Part of the EIA/TIA 568A standard.)
Category 7(Cat7) –CAT 7 cable, whilst being the more expensive option, is also considered the most durable, and has a longer lifespan than CAT 5 and CAT 6, improving its overall return on investment, and is the best choice for wiring with the future in mind.
Category 8- Category 8, or just Cat8, is the latest IEEE standard in copper Ethernet cable. It represents a significant leap in data transfer speed over the earlier Cat7 and Cat6a cables. It uses standard RJ45 connectors and is backward compatible with previous standards.
Ethernet – a set of network cabling and network access protocol standards for bus topology computer networks invented by Xerox but now controlled by the 802.3 subcommittees of the IEEE.
Fiber optic – a technology that uses glass or plastic threads or wires to transmit information. Now applies to so much more than just data transmission goes through everything that has to do with av and control and it is “inwall” rated because glass is not “inductive” “glass is an insulator
LAN (local area network) – a computer network limited to the immediate area, usually the same building or floor of a building. The Internet is a globally-connected network of computers that enables people to share information and communicate with each other. An intranet, on the other hand, is a local or restricted network that enables people to store, organize, and share information within an organization.
Cable shielding– a physical layer in some cables used to protect signals and sometimes used as a return path for current. Three basic types foil, braid, and combination.
Equipment rack – a centralized housing unit that protects and organizes electronic equipment.
Matrix switcher – an electronic device with multiple inputs and outputs, the matrix allows any input to be connected to any one, several, or all of the outputs. One audio one video
Rack unit (RU) – unit of measure of the vertical space in a rack. One RU equals 1.75 inches (44.5 mm).
Streaming video and audio – sequence of “moving images” or “sounds” sent in a continuous, compressed stream over the Internet and displayed by the viewer as they arrive. With streaming video or audio, a web user does not have to wait to download a large file before seeing the video or hearing the sound.
BTU-Measurement of heat. The British thermal unit is a unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is also part of the United States customary units. Heat is now known to be equivalent to energy.
Still, stumped? Look here for a super long list of terms. https://cie-group.com/how-to-av/videos-and-blogs/av-terms
Thanks For Reading!
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