Here's another one:
A
A/D converter - Analog to Digital converter - Converts an analog audio signal to it’s equivalent binary data form.
Absorption - The ability of a surface to absorb sound energy. The absorption coefficient of a material is a number between 0 and 1.
AC - Alternating Current
Acoustics - The study the movement of sound.
Alternating Current - Electrical current which changes direction periodically. Normal house current is Alternating Current.
Ambience - The characteristic sound of a location that tells the listener where he/she is. i.e. concert hall, stadium, etc. The ambience is a function of the reverberation of sound.
Ambient Noise - The sound that exists in a room that does not come from a loudspeaker, musical instrument or some other intentional sound source. A person speaking to an audience is not ambient noise. Many people conversing is ambient noise.
American Wire Gauge (AWG) - A system for measuring the diameter of wire. The lower the AWG number, the larger the diameter.
Ampere (AMP) - The standard measure of current flow. The amount of current that flows past a point in an electrical circuit. One amp is equal to one Coulomb of charge flowing past a point in one second.
Amplifier - A device that allows a small amount of input power to control a larger amount of output power. In sound systems an amplifier converts the small electrical signal from a microphone or other source into the larger electrical signal required to power the loudspeakers.
Amplitude - The peak to peak size of a waveform. For audio purposes, the greater the amplitude of the signal, the louder the sound will be.
Analog - In sound terms analog signals are electrical signals that are exact replicas of the waveforms of the original sound pressure wave in the air.
Anechoic - Echo free. An anechoic room has no reflected sound. This is accomplished by treating all of the room’s surfaces with sound absorbing material.
Array - The term used to describe a group of speakers positioned in one location. An array can be multiple stacked or hung speakers. See also cluster.
Assign - To switch or route a signal to a particular signal path or combination of signal paths.
Attack time - A term used in compressors and expanders. It refers to the time delay between when the device senses the signal and when the device completes it’s compression or expansion.
Attenuator - A device which reduces the strength of an electrical signal by some fixed amount.
Auxiliary Return - A line level input on a mixing console. Auxiliary returns are generally used as inputs for effects processors.
Auxiliary Send - An output bus which can receive inputs from each mix channel and send it to an effects processor. Auxiliary sends can also be used as additional output mixes for monitors, recording, etc. Each mix channel will have a separate level control for each aux send.
Axis - An imaginary line that is perpendicular to the front face of a microphone or loudspeaker diaphragm. For microphones, sounds reaching the microphone at an angle to the axis are said to be off axis.
B
Baffle - A panel or other surface whose purpose is to prevent the passage of sound.
Balanced Line - A three conductor line. One conductor carries the signal, one conductor carries an inverted copy of the signal and one conductor is the ground. At the destination the inverted copy is inverted again and the signals are added together. Any noise induced in the conductors will cancel each other out leaving only the original signal.
Bandwidth - The band of frequencies that pass through a device with a loss of less than 3dB. Bandwidth is expressed in Hertz or musical octaves.
Bass - Low end of the audible frequency spectrum.
Bi-amping - A method of amplification in which the frequency spectrum of the signal to be amplified is split into low and high frequencies before it is amplified. This method produces a cleaner sound with less distortion.
Bi-radial horn - A horn type speaker in which the vertical and horizontal surfaces flare outward at different rates.
BNC Connector - A connector found on some mixers for connecting a high intensity lamp. The same connector is also used on some test equipment and some computer networks.
Boundary Layer - The region near a reflective surface where the phase shift between the direct and reflected sound wave is negligible.
Bus - A mixer bus usually carries signals from a number of inputs to a mixing amplifier.
C
Cable - Any length of stranded wire. Electrical cable generally consists of multiple stranded copper wire conductors insulated with a rubber or plastic sheath. Electrical cable comes in various sizes of wire and varying numbers of conductors depending on the purpose. Speaker cable is usually two conductor. Microphone cable is typically three conductor (balanced) with a shield.
Cardioid Microphone - A relatively unidirectional microphone. Cardiod microphones attenuate the 90o off axis signal 6dB.
Cascading - Connecting the output of one mixer to inputs on another mixer in order to increase the number of available mixer inputs.
Channel - A discrete (separate) input with it’s own input and output level and equalization controls.
Channel Fader - The output level control for an individual channel. Channel faders are usually slide potentiometers rather than rotary potentiometers.
Channel Path - The signal path from the input connector to the point where the channel’s signal is combined with other inputs.
Chorus Effect - The combination of a direct sound and several delayed replicas to simulate the sound of multiple instruments or voices playing or singing the same part.
Clipping - Distortion in a piece of audio equipment when the input signal level peaks exceed the capacity of the equipment.
Cluster - An array of speakers hung from the ceiling.
Coloration - Audible alterations to the sound being reproduced due to the response curves of the microphone, loudspeaker or the room.
Compressor - A device used to reduce the dynamic range (difference between softest and loudest) of a signal. Compressors are used on the inputs to tape recorders and other equipment with limited dynamic range handling capacity.
Condenser Microphone - A microphone in which the pickup element is a capacitor. Condenser microphones require a voltage source, either internal or phantom power in order to function.
Connector - The terminator at the end of a cable that allows the cable to be connected to a piece of equipment or to another cable.
Console - The device to which all of the sound sources are connected for level control, signal processing and routing to it’s ultimate destination.
Constant Voltage System - A method of distributing audio signals to speakers in multiple remote locations. This method is used in airports, department stores, schools and other locations where the same audio signal needs to be sent to multiple rooms. In this method a single amplifier sends the audio signal to a transformer which is connected to transformers at the individual speakers by small diameter high impedance wire. The amplifier is set for maximum output and each speaker has it’s own level control potentiometer. The sound quality of this type of system is generally poor due to the high cost of quality transformers. This type of system is commonly referred to as a 70 Volt system.
Coverage angle - The included angle between the points on either side of a loudspeaker axis at which the response is attenuated 6dB with respect to the on axis level.
Critical distance - The distance from a sound source at which the direct and reverberant energy are equal. The critical distance should be greater than the maximum distance between any listener and the sound source.
Crossover frequency - The frequency in a speaker crossover network at which the outputs of the two adjacent filters are both attenuated by 3dB.
Crossover network - A device which separates parts of an audio signal based on their frequencies. If the crossover is placed before the amplifier it is called an active crossover. If the crossover is placed after the amplifier it is called a passive crossover. An active crossover needs one amplifier for each part of the audio signal (generally two or three).
Crosstalk - Any occurrence of one channel’s signal on another channel.
Cueing - To get a sound source (not live, either tape or cd) ready for playback by making sure you are in the right position on the tape or cd and making sure that the level and EQ are set properly. This requires a special monitoring circuit on the sound board which only the mixing engineer can hear.
D
Damping - The loss of energy in a vibrating system. This loss is usually due to friction.
dB (Decibel) - The standard measure of loudness. One decibel is equal to 1/10th of a Bel. The decibel is actually a ratio of two quantities on a logarithmic scale and can be applied to many audio system parameters.
dBm - A unit of measurement of audio signal level where the signal level is referenced to 1 milliwatt.
dBu - A unit of measurement of audio signal level where the signal level is referenced to 0.775 Volts RMS into any impedance.
dBV - A unit of measurement of audio signal level where the signal level is referenced to 1 Volt RMS across any impedance.
Delay - An electronic circuit that delays the audio signal for some short period of time. Individual and multiple delays are used in reverbs and other effects units where they are mixed back in with the original signal to produce an effect. Delays are also used individually to compensate for differences in speaker placement relative to the sound source and the listener.
Destructive Interference - The interaction of two or more sound waves which cancel each other.
Detent - A point of slight physical resistance in the travel of a knob or slide control. Detents are usually used to indicate the center on a pan potentiometer or unity gain.
Diaphragm - The moving element of a microphone. The diaphragm converts the sound waves into mechanical motion.
Diffraction - The manner in which sound bends around obstacles.
Direct Box - An interface box which allows the connection of high impedance unbalanced sources, like guitars or other instruments, to the low level low impedance mic inputs on a mixer.
Direct Injection - The process of connecting an instrument or other sound source to a mixer without using a microphone.
Distortion - A measure of the difference in shape between the wave form into an electronic circuit and the resulting output wave.
Diversity - A type of wireless microphone receiver that uses two antenna. The signal coming from each antenna is compared and the stronger signal is used.
Dynamic Microphone - A microphone in which the pickup element is a coil moving in a magnetic field. Dynamic microphones do not require a power source to function. Dynamic microphones are less sensitive and more rugged than condenser microphones.
Dynamic Range - The range between the maximum and minimum sound levels that a sound system can handle. Dynamic range is usually expressed in decibels as the difference between the level at which clipping occurs and the noise floor of the equipment.
E
Echo - The reflection of sound from a surface. Echo is generally considered to be a distinct, recognizable repetition of a word, note or sound. Echo can occur naturally as a reflection, or it can be electronically simulated.
Effects Send - An output bus which can receive inputs from each mix channel and send it to an effects processor.
Electromagnetic Interference - A type of interference (noise) generated in audio cables and circuitry by magnetic fields operating nearby. The most common source of EMI in audio application is from normal electrical power lines running through the auditorium.
Equalizer - A device used to purposefully change the frequency response of a circuit to compensate for unequal frequency response of the room or the rest of the system. Any control that allows you to vary the signal level of a range of frequencies separately is an equalizer of sorts.
EQ Cut - A button on some mixers which allows you to compare a channels’ unequalized sound to the equalized sound.
F
Fader - A straight line audio level control. Also referred to as a slider.
Feedback - The squeal, ringing or rumble caused by the sound from the loudspeakers reaching the microphones and traveling back through the system over an over at a resonant frequency. The frequency of any feedback is determined by the characteristics of the room and the equipment.
Filter - A device used to remove a certain range of frequencies. A low cut (high pass) filter reduces or eliminates frequencies below its cutoff frequency. Other filters are high cut (low pass), bandpass and notch.
Flanging - Another term for phasing.
Flat - The term used to describe the the frequency response of a room or piece of equipment when no frequency is accentuated or attenuated more than any other. (The graph of sound level for each frequency is flat.)
Frequency - The number of times an event repeats itself in a given period. Frequency is measured in Hertz (Hz). One Hertz is one cycle per second.
G
Gain - The measure of how much a circuit amplifies a signal. Gain is normally specified in dB.
Graphic EQ - An equalizer which uses slide potentiometers for its boost and cut controls. The positions of the controls represent the graph of the frequency response of the equalizer.
Ground - Also referred to as earth or earth ground. Ground is the point of zero voltage in a circuit or system. All other voltages are measured in reference to ground. Ground connections are used as safety precautions to keep the equipment chassis (case) and controls at zero voltage to prevent shocking the operator. The safety ground is the third prong on a three prong plug. Various points in each piece of electrical equipment are also connected to ground to minimize stray voltages and currents. These connections are called technical ground.
Ground Loop - A problem that occurs when the technical ground and the safety ground in a system are connected at more than one place. Two or more connections will allow tiny currents to flow in the loops. These tiny currents can produce noise or hum in the system.
H
Haas Effect - The psychoacoustic effect which allows us to perceive direction. If a sound reaches both ears simultaneously at the same level the sound appears to be coming from directly in front of the listener. If the sound is louder or arrives earlier in one ear it appears to be coming from the louder or non-delayed side.
Handling Noise - The noise generated by mechanical vibrations or shocks picked up by a microphone. Handling noise can be brushing, popping, rustling or thumping sounds.
Headroom - The difference between nominal operating level and peak clipping in an audio system.
Hertz (Hz) - The unit of measure of frequency. One Hz is equal to 1 cycle per second. One kHz is equal to 1000 cycles per second.
High Pass Filter - A filter designed to pass high frequencies with little or no attenuation. A high pass filter filters out low frequencies.
Horn - A loudspeaker which uses a diaphragm attached to a metal horn. Horn type loudspeakers are used to reproduce the middle and high frequency ranges.
House - Anything having to do with the performance hall. Some examples are; house lights, house speakers, etc.
House Curve - The acoustic response curve of a room to pink noise. The peaks in a house curve are the frequencies at which feedback will occur first.
Hypercardioid Microphone - A directional microphone with greater side attenuation than a cardioid microphone but less rear attenuation.
I
Impedance - The AC resistance in an electrical circuit. Impedance is the combination of DC resistance and AC capacitance and inductance measured in ohms. Impedance can’t be measured by a DC ohmmeter.
Instrument Level - The signal level normally associated with electronic instruments, normally between -20 and -10 dBu.
J
Jack - A term used to describe any female connector. The opposite of a plug.
K
Knee - A sharp bend in an EQ response curve.
L
Lavalier Microphone - A miniature microphone which is attached to the speaker by a clip with a wire running to a belt pack which holds the electronics.
Level - A word used interchangeably with signal voltage, power, strength or volume. Some inputs are classified by their level i.e. mic level (-40dBu or lower), instrument level (-20 to -10dBu) and line level (-10 to +30dBu).
Line Level - A signal level between -10dBu and +30dBu.
Line Matching Transformer - A transformer that matches the impedance of one device to another.
Low Pass Filter - A filter designed to pass low frequencies with little or no attenuation. Low pass filters filter out high frequencies.
M
Main House Speakers - The main speakers in a sound reinforcement system.
Master - A control that affects the final output of a mixer. Also an original tape, not a copy.
Mic Level - The typical level of a microphone signal. Usually lower than -40 dBu.
Mic Preamp - An amplifier which boosts a mic level signal up to a line level signal. Each input channel which accepts mic level inputs will usually have a mic preamp and an associated trim control which is used for setting the gain of the mic preamp.
Microphone - A transducer which converts acoustic energy into electrical energy.
MIDI - Short for musical instrument digital interface. MIDI is the communications standard by which some musical instruments communicate.
Midrange Speaker - A speaker used to generate only the middle range of frequencies.
Mixer - A device used to combine multiple audio signals into a common output.
Monaural - Sound coming from one source (signal). Multiple speakers that have the same input are mono regardless of their number or placement. A better definition might be not stereo. Monaural sound does not contain any inherent directional information.
Monitor - A speaker or headphones used by the performers to hear themselves. Also the speakers used by the recording engineer to listen to the recording in progress.
Mono - See monaural
Mute - A switch on a mixer that reduces the level of a channels output to 0 regardless of the channel fader position.
N
Noise - Any unwanted sound either electronic or natural.
Noise Floor - The residual level of noise in a system, what you hear through the speakers if you turn the master fader all the way up with no input.
Noise Gate - An amplifier that produces no output signal until the input signal exceeds a predetermined level.
Notch Filter - A filter that affects a very narrow range of frequencies.
O
Octave - The difference between any two frequencies where the first frequency is 1/2 that of the second frequency.
Omnidirectional Microphone - A microphone that is equally sensitive in all directions.
Overload - Any time that the input signal level to a circuit exceeds the capacity of the circuit.
P
Pad - See attenuator.
Pan Pot - A panoramic potentiometer. A pan pot is used to position a monaural sound source in a stereo mix. The pan pot adjusts the relative level of the signal to the two stereo channels giving the sense of position.
Parametric Equalizer - An equalizer with controls that let you adjust the center frequency, gain and bandwidth of each filter.
Patch Bay - A panel with many jacks organized into two rows which are interconnected. Patch bay jacks come normalled and half normalled. For normalled patch bays the top row of jacks are normally connected to the bottom row of jacks. When a plug is inserted into the top jack the connection to the bottom jack is broken. For half normalled the signal is not disconnected when a plug is inserted.
Patch Panel - A panel with many connectors on it.
Pink Noise - Electronically generated sound that has equal energy for all frequencies in each octave. The energy is decreased approximately 3dB per octave to simulate the loudness perception of the human ear.
Phantom Power - Power supplied to condenser microphones from a mixer or phantom power source. Phantom power is carried to the microphone over the standard mic cable.
Phasing - A delay effect where the original signal is mixed with a short delay.
Phone Plug - A 1/4” diameter plug typically found on headphone jacks and line inputs and outputs.
Phono Plug - A plug commonly found on consumer audio equipment. Phono plugs are usually found on cassette deck inputs and outputs. This type of plug is commonly referred to as an RCA plug.
Polar Pattern - The graphic representation of microphone sensitivity or loudspeaker coverage at various frequencies throughout the circle around the element.
Pop Filter - A wind screen that fits over the exterior of a microphone element which reduces the sound pressure level of the plosive sounds (p’s, b’s and t’s) which cause popping.
Pre/Post Fader - Any send that is pre-fader is not affected by the position of the channel fader. Any send that is post-fader is affected by the position of the channel fader.
Pressure Zone Boundary Microphone - A microphone which picks up the sound from the area close to the reflective surface that they are placed on. These mics are commonly used on stage where they are placed on the hard wood floor.
PFL (Pre Fader Listen) - The ability to listen to a channel without sending it to the audience.
Pot - A potentiometer. A pot is a variable resistor. Pots are used to vary the potential (voltage) output of a circuit. A fader is a slide potentiometer. A pan pot or aux send level is a rotary potentiometer.
Proximity Effect - The property of many directional microphones which causes the bass response to be increased when the source is very close to the microphone.
Q
Q - The term used to describe the bandwidth of a filter. Q is equal to the center frequency of the filter divided by the difference between the upper and lower -3dB frequencies. The higher the Q the narrower the filter.
R
Radial Horn - A horn whose top and bottom surfaces flare outward but with straight vertical sides.
RCA Jack - The female counterpart to a RCA or phono plug.
RCA Plug - See phono plug.
Reflection - The return of a sound wave from an obstruction in its path.
Refraction - The bending of a waveform due to a change in temperature within the transmission medium (air for our purposes) or as it passes from one medium to another.
Resonance - All objects or system have a natural frequency at which they vibrate. When the sound frequency produced by the object or system is at this natural frequency the sound is reinforced.
Return - A mixer line input which is used to return sound from an outboard processor (reverb, delay etc.) to the mix.
Reverberation - The sound remaining in a room after the source of the sound has stopped.
RMS - Root Mean Square. RMS is the common method for measuring AC and audio voltages.
S
Send - A secondary mix output. Sends are used for monitors, and other auxiliary outputs.
Seventy Volt (70V) System - A type of public address sound distribution which uses a transformer on the output of an amplifier to provide the audio signal to multiple speakers in locations other than the house. Seventy volt systems do not produce the same sound quality as regular systems.
Shield - A conductive tube around the center signal conductors that protects the center conductors from electromagnetic fields which could induce noise into the system.
Shock Mount - Any suspension system that mechanically isolates a piece of equipment from vibration occurring in the object the equipment is mounted to.
Sibilance - The sound produced by pronouncing s, sh or ch.
Signal to Noise Ratio - The ratio between the average signal produced and the background noise. SNR is usually expressed in decibels.
Snake - A patch panel with a long multiple conductor cable. A snake is many microphone and line cables in one assembly.
Solo - A circuit that allows the engineer to listen to individual channels or buses singly or in combination with other soloed signals.
Sound Pressure Level - The intensity of a sound wave. Sound pressure level (SPL) is normally measured in dB compared to no sound.
Stage Box - The patch panel part of a snake.
Stereo - The process of simulating the spatial relationships of actual sound sources by varying the respective levels coming from two speakers.
Subwoofer - A specific type of speaker dedicated to reproducing very very low frequency sound.
Sweep EQ - An equalization filter whose center point can be varied.
T
Talkback - A mixer input that is routed to the monitor sends to allow the mix engineer to talk to the performers.
Threshold of hearing - The minimum sound pressure level of a pure tone which can be perceived by a person with good hearing. The threshold of hearing is defined as 0dB SPL which is equal to a sound pressure of 20x10-6.
Timbre - The attribute that allows a person to distinguish the difference between two sounds of the same pitch and loudness.
Transducer - Any device which converts an input signal to an output signal with a different energy form. Microphones convert acoustic energy into electrical energy. Loudspeakers convert electrical energy into acoustic energy.
Trim - The gain adjustment for the first amplification stage of a mixer input channel. The trim control is used to correct for the differing signal levels produced by different microphones and other input devices.
TRS - (Tip Ring Sleeve) A type of 1/4” phone connector (jack or plug) that utilizes three conductors. TRS jacks are often referred to as stereo connectors.
TS - (Tip Sleeve) A type of 1/4” phone jack that utilizes two conductors.
Tweeter - A loudspeaker that is dedicated to reproducing high frequencies.
U
Unbalanced - An electrical circuit where the two legs of the circuit are not balanced with respect to ground. In an unbalanced circuit one of the two legs is generally at ground potential.
Unity Gain - A system or circuit where the input level and the output level are the same has a gain equal to 1 or unity. A circuit may affect the content without affecting the gain.
V
Voltage - A measure of the electrical force which causes current to flow.
W
Wet Signal - A signal with one or more effects added in.
White Noise - A full audio spectrum signal with the same energy level at all frequencies.
Windscreen - A foam screen placed over a microphone to cut wind noise.
Woofer - A loudspeaker dedicated to producing low frequency sound.
Working distance - The distance between the sound source and the microphone.
X
XLR Connector - A 3 prong connector commonly found on microphones.
) on the definitions on some of the technical terms.
