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Home -> Church Audio & Acoustics Glossary -> A
Church Audio & Acoustics Glossary
| This glossary is being put online to help with unfamiliar words when visiting this site. Since this is a web site devoted to church audio and acoustics, the glossary will cover common words used when talking about church audio and acoustics. This is only one step beyond typical glossary listings, since it's specific to churches. New words will be added as they come up; if you have any suggestions, please let us know! There are a number of words that relate to churches in general, as well as video and lighting terms. You usually need to know a little of everything... Many words don't have definitions yet, we're working on it. This is a project in motion; it will be updated as time permits. If you would like to contribute a definition for any words listed here, just let us know, thanks! |
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| A
absorption The property of a material that changes acoustic energy into
(usually) heat energy. A material or surface that absorbs sound
waves does not reflect them. Absorption of a given material is
frequency dependant as well as being affected by the size, shape,
location, and mounting method used. absorption coefficient A rating of a material that tells how much sound energy it absorbs
at given frequencies. Measured in Sabines. AC Alternating Current. Electrical current that changes its direction
of flow. Standard home power is 60HZ AC. This means the current
changes direction 60 times each second. Audio lines carry AC current. active circuitry Electrical circuits which require external power to operate.
Circuits using transistors, integrated circuits and the like are
active circuits. A simple inline pad made of resistors is passive,
it doesn't require external power to operate. active crossover A device that takes a full-range audio signal and splits it into
2, 3, 4, or even 5 different segments. A simple 2-way crossover
provides an output for the lows and an output for the highs. Usually
a control is given which allows the user to select what the crossover
point will be. The outputs then feed separate amplifiers and speakers.
This method provides better crossover linearity and power usage. acoustics The branch of physics that deals with sound. A/D Analog or Digital conversion. ADA Americans with Disabilities Act. Specifically as it pertains to sound, an act of Congress which states that all public meeting facilities (exempting religious and federal) be equipped with approved listening assistive or "hearing impaired" services/devices. adapter When two or more connectors do not mate physically, an adapter permits the connection to be made. There are hundreds of different combinations of adapters available. ADAT Digital multitrack recording system from Alesis Corporation realeased 1993. AES Audio Engineering Society. The only professional society devoted exclusively to audio technology. AF Audio frequencies (as opposed to RF (radio frequencies)). AFL After Fade Listen. The function of a button found on the input
channels of a mixer. Engaging this feature causes the signal found
after the channel fader to be routed to a special headphone circuit
(typically). This circuit allows the operator to listen to the
post (or after) fader signal separate from the rest of the mix. Alcons A scale of the percentage of the articulation loss of consonants. A formula derived by V.M.A. Peutz based on distance, RT60, Volume of air in the room, the N factor, and the Q of the source. A measure of how difficult it is to understand someone in a room. The lower the number, the better for speech intelligibility. AM Amplitide Modulation. Changes in the carier level shifts. ambiance The sound of a room and its natural reverberation. ambiant noise The amount of noise in a room without any primay sound. The background noises in a room (HVAC, traffic noise, etc.). amp Abbreviation for amplifier. Abbreviation for ampere. ampere The unit used to measure electrical current. amplifier A device that increases the power of a signal. An audio power amplifier takes the small mic or line-level signal and raises it so it can power the speakers. amplitude The distance a waveform is above or below the zero line. The strength of sound pressure or voltage. analog An signal that's made up of an infinite number of levels between
it's highest and lowest point. An analog recording is a recording
(storage) of the continuously changing electrical voltages. Conventional
cassette and video recordings are analog, whereas a CD is digital. ANSI American National Standards Institute. Organization that sets the standards used for U.S. audio & visual equipment. antenna A piece of wire that can be flat or round, rigid or flexible, hidden or visible that picks up (recieves) or sends (transmits) radio waves in the air. antenna splitter A device that electronically splits an antenna signal to feed several receivers. This way, several receivers can share the same antenna or set of antennas (assuming they all use a similar antenna length). anvil One of three tiny bones in the middle ear that helps transmit
sound waves from the outer ear to the cochlea. ASCII American Standard Code for Information Interchange. A standard code in which alphabetic, numeric, and special characters are symbolized by a 7-bit number. The number is made up of 0's and 1's. assign On an audio mixer, to route the audio signal to a particular place. For example, assigning a microphone channel to subgroup 1. Usually in the form of a switch and/or a pan-pot. assistive listening system Any device (except for a hearing aid) which helps a hearing impaired person. This can be in the form of a wired pair of headphones, FM wireless headphones, infrared receiver with headphones, etc. The signal sent to the headphones is as direct as possible--that is, extraneous noises and room reverberations are not accepted. Usually a direct feed from the house mixer is used to feed such a system. attack The rate at which a sound increases in volume. attenuate A drop in signal level. Opposite of amplifying a signal, an attenuated signal has had a drop in signal strength. attenuator A device that controls the amplitude of a signal. Sometimes refered to as a volume control. Common examples are the gain control on a mixer, or the fader on a mixer. audio Sound signals in the air (sound waves) or flowing through a wire (electrical current). audio chain A series of audio equipment that's interconnected. A simple sound reinforcement audio chain would be as follows: microphone, mixer, equalizer, amplifier, speaker. audio snake see snake audio spectrum The range of audible audio frequencies to humans. Typically being 20Hz to 20KHz. audio spectrum analyzer Piece of equipment that lets you have a visual look at the power level of a sound at different frequencies. Often called a real-time analyzer as it lets you look at the sound as it's happening. Units display information at 1/3-octave bands typically, but some equipment can show up to 1/12-octave resolution or finer. audiogram A graph that shows a persons ability to hear sounds at different frequencies. autoformer
automatic mixer A mixer that can be set so microphones are automatically turned on when a specified amount of sound level is reached at the microphone. Auto-mixers can also include controls which allow one microphone to have priority over the others. This feature would be used for the main microphone so the person in charge can interrupt anyone else. AUX Abbreviation for auxiliary. auxiliary send A control on a mixer input channel that allows a signal separate from the main signal to feed other equipment. Such uses include an auxiliary feed for tape recording, monitor mixes, and assistive listening systems. The use of an auxiliary send allows the user to create different mixes for each send which are separate from the main mix. AWG American Wire Gauge. National standard for measuring a wire's conductor size. The smaller the number, the larger the wire size (12AWG is larger than 18AWG). axis The point horizontally and vertically centered in front of a microphone or speaker. Certain microphones have different frequency response curves at different points off-axis. A speaker's directivity is measured off axis. Microphones and speakers typically behave differently off axis than they do on axis. |
| Sources No, we didn't write all of these definitions ourselves. What we did was take a word, read several definitions from books and listings on the internet, then write our own version. In some cases we used phrases word-for-word, but usually we reworded the definition to be more clear and applicable to church audio and acoustics. Glen Ballou, Handbook for Sound Engineers–The New Audio Cyclopedia.
Howard W. Sams & Co., MacMillan, Inc. 1991 |