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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 measure of the acoustic absorptive characteristics of a material named after Professor W.C. Sabine. Open air is said to be 1 Sabin. Other materials have a coefficients beween 0 (totally reflective) and 1 (totally absorbtive). Charts listing these numbers are available and give the absorbtion coefficients at different frequencies.


    A mild to hot spicy sauce served with chips and dip.
    see also dip


    A feed, an output signal. Usually line level. On mixer, usually refers to either an effects or auxiliary output designed to go to an outboard device and return the processed signal to a "return".
    see return


    1. The ability of a microphone to pickup very quiet sounds results in a higher sensitivity number.
    2. The ability for a speaker to produce a louder sound when fed the same amount of power as another speaker. The SPL output for a given input level (usually tested with 1 watt of input power with a test instrument 1 meter directly in front of the speaker).
    3. The ability of a wireless microphone receiver to pickup very weak RF signal levels.

sensorineural hearing loss


SDL (servo-drive loudspeaker)

shaped sound

    A sound that's not flat. Either the frequency response of a device as in shaped microphone for vocal response, or a signal that has been adjusted for equalization.


    A type of equalization where the frequencies either above or below a given point are raised or lowered equally. Shown on a graph, it would be flat up to the frequency point, then it would go up or down to a given level and then flatten out again. Typically the high and low frequency equalizer controls are shelving type controls.


    1. A wiring or covering over either a wire or circuit which blocks RFI from entering the wiring and thereby causing noise. In microphone wiring, it may be a foil type wrapping or a braided wire. Foil gives a 100% shield while a braided shield is less than 90%. The shiled of a wire is connected to a drain wire (in the case of a foil shield) which is then connected to pin 1 of an XLR type connector.
    2. Faith–as in spiritual armour.

shielded cable

    A cable whose internal wires are covered by a shield of some sort.
    see shield

shock mount

    A device that holds something else stable even if it's bumped or shaken. In microphones, the shock mount goes on a microphone stand so if the stand is bumped, the microphone doesn't pick up the vibrations (noise).


    1. Term for short circuit. A circuit where two (or more) wires are (usually) connected unintentionally. It often results in no sound or damaging equipement or a component.
    2. The opposite of tall. "The stool was so short I couldn't see the stage over the sound board."

shotgun microphone

    A type of supercardioid microphone which looks like a long (up to 3') tube with slits in it. Very directional.


    Hissing sound. The "S" sound in "this", "rose", "pressure".


    Refers to an electrical current present on a wire or in a circuit which represents a soundwave. The electrical representation of the sound going down the wires from one piece of equipment to another.

signal ground

signal level

signal processor

    A category of electronic devices which cause some type of change to an audio signal. This includes (but is not limited to) equalizers, delay units, effects units, limiters, and crossovers.

signal to noise ratio (S/N)

    The ratio between the nominal level of a signal (0 dBm) and the general circuit noise level (noise floor) measured in dB. All electronic devices produce noise. The S/N ratio is a measure of how quet the device is by indicating how low the level is of the inherant noise.


    Solo In Place.

slap echo

    A single, strong echo heard off a surface.
    see flutter echo


    The largest contact of a 1/4" (or mini) phone type connector. The cable shield or common wire is connected to this point in balanced wiring, the negative and shield in unbalanced wiring is connected here. Same as the shell of the connector.

sliding fader

    A variable resistor that moves in a straight linear fashion as opposed to a rotory control. Typically used on mixers to adjust the channel voume level.



    see signal to noise ratio


    1. A long multi-pair cable usually with a box at one end (the head) with multiple input and some output jacks and connectors at the other end to allow a microphone to be plugged into the head, then the corresponding connector plugged into a mixer at the other. A multi channel extension cord for microphones.
    2. An animal without legs. AKA serpent as in the animal that deceived Eve in the Garden of Eden.
    3. A person who acts deceptively and sell you inferior audio equipment at outrageous prices.



    Another term for PFL. Listening to one (solo) channel of a mixer.
    see PFL


    Another term for AFL. Listening to one (solo) channel of a mixer after EQ, after inserts, after panning, after all processing.
    see AFL

sound chain

    The link (relationship) between the various components of a system. How they are wired together.

sound pressure level

    The power level of sound being the sound pressure squared, referenced to 20 mPa2 measured in dB. Commonly, how loud the sound is measured in decibels. Speech is around 70-80 dB at three feet. Normal background noise on average is 50-60dB. 120dB is the threshold of pain. 200dB is 50lbs of TNT detonated 10 feet away.

sound reinforcement

    The act or application of audio processing equipment to reinforce and amplify sound instantaneously. Adding the processed sound to that of natural sound from the sound source so that all can hear. One of the three major applications of audio equipment as opposed to recording or broadcast. Sound reinforcement takes a weak sound and makes it loud enough for people to hear.

sound wave

    An oscilation of air pressure. One wave is measured from the point of null (average room) pressure past both points of greatest (crest) and least (trough) pressure to the point of normal pressure. The length of the wave is measured in feet. The frequency is measured in Hertz (when time is factored in).


    see loudspeaker

speaker level


    A type of connector used for speaker connections developed by the company Neutrik. Has four or eight contacts (depending on the model). The plug locks into the jack so it can't be pulled out. Becoming accepted as the standard professional speaker connector due to its electrical handling and mechanical features.

speech intelligibility

    How well you can understand what is being said. Though you may "hear" the sound, you may not understand it (and it's useless). Measurements can be taken to quantify what the intelligibility of a room and/or sound system are.
    see alcons

speed of sound

    The speed at which sound waves travel through a medium (usually air). Since the speed of waves is affected by the density of the medium and the density is affected by the temperature and pressure, the speed of sound through aid varies depending on these (and other) factors. A true measurement must state under what conditions it was measured. The standard reference is 1,130 feet per second at 59-degrees F at sea level (standard barametric pressure). The speed of sound increases with humidity, too.


    1. Short for spill-over. Refers to sound that's heard in an area it's not intended to be in. The most common example is stage monitor spill--when the sound from stage monitors is heard in the audience/congregational seating area.
    2. What you must be very, VERY careful not to do when drinking and running a sound board.


    Sound Pressure Level.


    A device which splits something into multiple parts, usually having multiple outputs the exact same as the original (as opposed to dividing something). In sound systems, common splitters are antenna splitters to allow multiple wireless receivers to operate from the same antenna(s) or an audio signal splitter to send one signal to multiple destinations.
    see distribution amplifier


    1. Fanning the walls in a room so they are not parallel.
    2. Angling adjacent speaker boxes or drivers away from each other to achiever the appropriate and desired coverage while minimizing comb filtering.

spot (light)

spring reverb

    A device that creates a reverb effect by passing an electrical signal through a coil spring. Is the older, cheaper, and more limited design compared to digital effects units. Has the annoying habit of causing a loud bang, boing, or slap when the unit is bumped (usually during the quietest part of the service).


    Term used for a mid-range speaker in a loudspeaker cabinet.


    The circuit in a wireless microphone reciever that automatically mutes (turns off) the audio output when the RF level drops out or is too weak to be received properly.

stage rumble

    The noise caused by feet on the floor (stage) or any other undesired sounds generated on the stage such as prop movement or microphone stand movement. Most common in wooden stages (which tend to magnify the low frequency portions of the sounds).

stage left

stage right

stand adapter

    Any mechanical device that allows a device to be attached to a stand such as a microphone or speaker stand.
    see microphone clip

standing wave


    Derived from a Greek word meaning "solid". The sound is solid or sounding like it's coming from one side or the other instead of from the individual speakers themselves. Commonly though it refers to any two channel audio system especially as contrasted to mono. Usually the two channels have different information (signals) on them which means that if you're closer to one speaker than the other, you'll hear an unbalanced reproduction which is why most sound reinforcement systems are done in mono.

stereo image

    A panoramic acoustical image derived from two sources. The effect of being able to identify the location of different sounds from different places anywhere between sources.

stereo microphone

    A microphone that has two (or more) elements in it to derive a stereo image of the source. It has two (different) output signals as well.

stereo return

    A dual channel line input on a mixer with one set of controls for both inputs. Usually has limited control capability (EQ, etc.) It's designed to take the output of an effects device (where the effect is returned in to the mixer).


strike (set)


    1. a mixer subgroup.
    2. a subwoofer.


    A fader on larger mixers that receives the level of all the input channels that are assigned to it, controls the level of the combined signal, and then passes that signa on to the master level controls. Often subgroups have their own independant outputs to allow for multi-track recording. Features on a subgroup vary depending on the mixer. The concept is to allow multiple microphones that are related (like all the drum mics or all the male background vocals) to have one overall control each.
    see VCA


    Term for subgroup. Submasters are usually distinguished from subroups in that there will only be a left and right (subgroups usually have 4 to 8 controls).


    A mixer that's used to mix several sources together and then output the signal to another mixer. This allows more inputs to be mixed than the master mixer can handle (or for the submix to be done at a location different than where the main mixer is).


    Short for subwoofer or subgroups.


    A speaker that's designed to reproduce very low frequencies (only), typically below 50Hz. Usually employs the use of very large cone drivers. The frequency range and size of the subwoofers is relative to the rest of the speaker system they are designed to accompany. If a main speaker has a frequency response down to only 80Hz, the subwoofer used may cover 50Hz to 80Hz. If the main system goes down to 50Hz, the subs may operate from 30Hz to 50Hz.

summed mono

    A mono signal that's derived by mixing the left and right stereo signals together. The mono signal is then whatever the sum of the two signals. If the two signals contain information that's opposite each other, it will cancel (leaving no signal). Any variation of the two signals will result in some frequencies partially or totally cancelling while others will be enhanced. This is in contrast to discrete mono where the signal is always and only one signal.

supercardioid microphone

    A microphone that's more directional than a cardioid microphone. Typical specifications are: coverage angle=115-degrees, maximum rejection=126-degrees (2-points)
    see also: bidirectional; cardioid; hypercardioid; omnidirectional

surface microphone

    see boundry microphone

surround sound

    A speaker system that has speakers both in front and behind the listener. Can mean a variety of channel separation and speaker placement systems. Most commonly, involves left and righ tchannels placed to either side of the front "screen" each with different signal information. A center channel wil be placed in the middle of the front screen but may be either a discrete or summed mono channel (used primarily for speech). Typically in a theater, the side and back speakers are all one discrete channel. In current home theaters, the back speakers are usually a mix of the left and right channels at lover levels. The subwoofers are usually a summed mono signal.


sweepable EQ

    An equalizing control or filter that has a variable center frequency. This allows the user to cut or boost a range of frequencies centered around a frequency that's determined by a separate contorl rather than only the range of frequencies pre-determined by the device.

sweetspot (speaker)


    Vertical and horizontal pulses in a composite video signal that maintain the horizontal and vertical scanning procedures of the video picture signal.



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!