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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 capella

vocal music without the accompaniment of instruments.


    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.
    see also absorption coefficient

absorption coefficient

    A rating of a material that tells how much sound energy it absorbs at given frequencies. Measured in Sabines.
    see also Sabine


    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.
    see also DC; HZ; Hertz

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.
    see also passive circuitry

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.
    see also passive crossover


    The branch of physics that deals with sound.


    Analog or Digital conversion.
    see also D/A


    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.


    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.


    Digital multitrack recording system from Alesis Corporation realeased 1993.


    Audio Engineering Society. The only professional society devoted exclusively to audio technology.


    Audio frequencies (as opposed to RF (radio frequencies)).


    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.
    see also PFL; solo


    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.


    Amplitide Modulation. Changes in the carier level shifts.
    see also carrier; FM


    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.).


    Abbreviation for amplifier. Abbreviation for ampere.
    see also amplifier; ampere.


    The unit used to measure electrical current.
    see also current


    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.


    The distance a waveform is above or below the zero line. The strength of sound pressure or voltage.


    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.
    see also digital


    American National Standards Institute. Organization that sets the standards used for U.S. audio & visual equipment.


    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).


    One of three tiny bones in the middle ear that helps transmit sound waves from the outer ear to the cochlea.
    see also hammer, stirrup


    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.


    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.


    The rate at which a sound increases in volume.
    see also decay


    A drop in signal level. Opposite of amplifying a signal, an attenuated signal has had a drop in signal strength.


    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.


    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.


    A graph that shows a persons ability to hear sounds at different frequencies.


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.


    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.


    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).


    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.



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
Don & Carolyn Davis, Sound System Engineering. Howard W. Sams & Co., MacMillan, Inc. 1997
Glossary of Wireless Microphone Terms. Lectrosonics, http://www.lectro.com/wg/wgglos.htm 11/9/98
John Eiche, Guide to Sound Systems for Worship. Hal Leonard Publishing Corp, 1990
Tim Vear, Microphone Selection and Application for Church Sound Systems. Shure Brothers, 1996
Tim Vear, Selection and Operation of Wireless Microphone Systems. Shure Brothers, 1994
Microphone Techniques for Music, Shure Brothers, 1994
Joe De Buglio, Why Are Church Sound Systems & Church Acoustics So Confusing?, 1998
various handbooks and users manuals for specific equipment especially by Mackie, Spirit, Shure, and Rane.

EXTREME thanks to Stephen Lund of LaRue Electrical Specialties, who began writing a glossary of terms, never fully completed it, but has passed his words and definitions on to us for use in this glossary. There are many definitions he had written that were so simple to understand, we took them as-is without any editing. We finally finished it! (...almost) Thanks a million, Stephen!