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Live Sound Glossary of Terms


Absorption - The attenuation of sound level that occurs when a sound wave passes through a medium or strikes a surface, which result in the conversion of sound energy into energy such as heat.

Acoustics - The science and study of sound, or the effect a given environment has on sound.

Amplifier - A device that increases the amplitude of a signal.

Attack - The time taken for the compressor or limiter to respond to the transient that has exceeded the threshold and attenuate the gain accordingly.

Attenuate - To reduce in amplitude or sound level; make quieter.

Bi-Amplified Systems - A loudspeaker system with a crossover and two independent power amplifiers, each handling their own half of the frequency spectrum and feeding a separate speaker system.

Balanced Connections - Impedance matched audio connections that use three-conductor connectors such a XLR or TRS connectors. Balanced lines are less susceptible to hum and can carry audio signals over longer distances.

Boomy - Listening term, refers to an excessive amount of additional bass response that has a less focused attack.

Bus - A mixing console term that refers to a internal pathway used to route audio signals between channels, inputs, and outputs of a mixing console or digital audio workstation.

Bright - Listening term, refers to trebly sound that has a lot of high frequency response.

Clipping - Distortion as a result of the top of a digital waveform being cut off caused by a signal overloading a gain stage of a digital device.

Coloration - Listening term. The emphasis or reduction in a characteristic of the original sound.

Compression - The process of attenuating the volume of loud sounds and amplifying the volume of quieter sounds to reduce the overall dynamic range of the audio signal.

Compression Driver - A mid or high-frequency speaker comprising a small diaphragm and voice coil coupled to a large magnet structure, which is usually then mounted into a horn.

Coverage Pattern - The angle of a loudspeakers beamwidth averaged over the high frequency responses enclosed within the specified range of -6dB on a frequency response polar plot. For example using the center of the high-frequency component as the 0° axis, the StageSource L3t can project 25° above and below the 0° axis, and 50° left and right of the 0° axis while maintaining an ideal frequency response and amplitude level.

Crossover - DSP controller filter that splits audio signal into separate frequency bands that are routed separately to loudspeaker drivers that are optimized for the specific frequency band.

Crossover Frequencies - The specific frequency bandwidths the DSP controlled crossover will split between separated loudspeaker drivers so that each driver can handle portions of the audio range it is optimized for.

DC Fault Protection - A type of power amp protection that prevents the loudspeaker from receiving DC current as a result of a power amp failure.

Decibel - A unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale. It is defined as dB = 10 x log(P1/P2), where P1 and P2 are the relative powers of the sound.

Direct box - Device used to connect a high-impedance, line level, or unbalanced signal to a low-impedance microphone level balanced input. Commonly used to connect a electric guitar or bass directly to a microphone preamplifier input.

Directivity - The angle of coverage for a loudspeaker’s projection vertically and horizontally, often expressed on specifications as ‘Directivity Index’ in decibels or as ‘Directivity Factor’ which is represented by Q. These specifications can help you to gauge how directional the loudspeaker is.

Directivity Factor (Q) - The mathematical expression of how directive a loudspeaker’s output is.This ratio is represented by the Q factor, a measurement of the on axis response compared to the average of the off-axis response over a specified frequency range. A spherical output source with equal output levels at all angles will have a Q factor of 1.

Directivity Index (DI) - The average increase in a loudspeaker’s sensitivity as a result of the directivity factor of a loudspeaker’s output. Represented by the value of dB, the on-axis level will have a increase in amplitude in relation to the level that would be radiated by a spherical output source of the same power, over the average of frequency range specified.

Dynamic Range - The amplitude range between the quietest level and loudest level that a audio device can capture, produce, or reproduce without distortion.

Equalizer - An adjustable audio filter that divides an audio signal’s frequency response into separated bandwidths, yielding the ability to increase or attenuate the amplitude of each bandwidth individually, in order to control the overall response of the audio signal.

Excursion Limiting - Regulatory protection against a loudspeaker’s voice coil from being forced to move forward or backward in an amount that exceeds what it is capable of.

Feedback - A constant ringing tone caused by the amplified sound of a loudspeaker system being captured by a microphone that is simultaneously being amplified by the same loudspeaker system, this causes the formation of a continuous feedback loop.

Free Field - A environment where sound produced can travel in all directions without reflections or exterior interference. This type of environment is used to simulate and measure the response of an audio source in open space.

Frequency - The measure of the rate of variations of a repetitive waveform, expressed in cycles per second or Hertz. In audio terms, frequency often refers to a specific tone within a range of a audio signal.

Frequency Range - The operational frequency response the loudspeaker reproduced at the specified output power.

Frequency Response - The bandwidth of frequencies that an audio device can capture, produce, or reproduce. Frequency response is measured from a low of 20Hz to a high of 20kHz with a +/- dB value indication of the amplitude variation existing across the frequency response when a test tone or sample is played back. All frequencies above and below a unit's Frequency Response are attenuated by a value greater than the +/- dB level indicated by the specification.

Gain - Adjustable volume control for a audio device’s input that increases the amplitude of a signal from the input to the output of the device. Also represented as the output voltage of a device divided by its input voltage, most commonly measured in decibels.

Graphic Equalizer - A equalizer that typically has a number of fixed-frequency bands, each with a slider that allows you to boost or cut the designated frequency.

Ground loop - A condition occurring when several ground pathways exist between two devices, resulting in hum and increased noise.

Half Space - A variation of the free field environment in which the audio source is placed or mounted against a solid barrier or baffle without reflections or exterior interference. This type of environment is used to simulate and measure the response of an audio source in half space. Compared to a free field environment response, a half-space environment will yield an increased response in low frequencies by an average of +6dB.

Headroom - The difference between the nominal operating level of a audio device and the level at which clipping occurs, usually measured in dB.

Hertz - The measure of the frequency of a vibrating object equivalent to cycles per second, it is often abbreviated as "Hz."

Highpass Filter - An audio filter that attenuates all frequencies below a user specified cutoff frequency by particular amount of db per octave.

Loudspeaker Horn - A horn shaped passive component of a loudspeaker that increases efficiency by improving the directivity and frequency response of the driver it is coupled with.

I/O - Abbreviation for "Input/Output."

kHz - 1000 Hertz.

Limiting - The process by which the amplitude of an audio device’s input or output is prevented from exceeding a user specified dB level.

Line-Level - The level of a audio device’s input or output operating level, typically a line level signal is +4dBm, while some audio devices will use -10 dBV instead. Line-level audio signals usually include keyboard/synth outputs, mixer outputs and signal processor outputs.

Loudspeaker - An electroacoustical transducer that converts electrical energy to sound energy.

Lowpass Filter - An audio filter that attenuates all frequencies above a user specified cutoff frequency by particular amount of db per octave.

Main Speaker(Mains) - The primary loudspeakers used to broadcast the output of a mixing console to the audience.

Maximum SPL Output - The maximum output volume achievable before clipping or a specified level of distortion occurs.

Millisecond - One one-thousandth of a second, often abbreviated as "ms".

Mixing Board - An audio device used for combining, routing, and adjusting the level, tone, and dynamics of audio signals, in turn summing the signals down to a monophonic or stereo signal that can be output to a recorder or loudspeaker.

Monitor - A loudspeaker used live or in the studio to help a performer hear playback of their performance or backing tracks.

Monophonic - A single-channel sound.

Mute - A function that decreases the volume of an audio signal or device to a level that is inaudible, which allows the volume to be cut on a device without having to adjust the volume control.

On-Axis - A response that is directly in front of a loudspeaker or microphone.

Off-Axis - A response that is not directly in front of a loudspeaker or microphone.

Off-Axis Response - A plot used to illustrate the response of a loudspeaker over a specified range of off-axis angles, with the measurement of the on-axis response used as the zero degree reference point.

Overcurrent Protection - A type of power amp protection that disables the output stage of the amplifier when a voltage greater than or equal to a specified value is detected.

Overtemprature Protection - A type of power amp protection that prevents the power amp from overheating by limiting the output power once a specified temperature has been reached.

Pan - A rotary control on a audio device used to position the audio signal between the left and right channels of a stereo sound field. The counter-clockwise position routes the signal to the left-channel output, the clockwise position routes the signal to the right–channel output, and the center position routes the signal equally to both the right and left channels.

Phantom Power - A method of powering a condenser microphone by sending 48 volts of DC current over the same XLR cable used to carry the microphone’s audio signal.

Parametric Equalizer - A equalizer that typically has three primary parameters: selectable center frequency for the frequency band, bandwidth control for how wide or narrow the frequency band is, and a gain control for how much of the frequency is boosted and cut.

Peak Output Power - The measurement of the maximum amount of watts a power amp can handle for an instant without distortion.

Power Amplifier - An audio device that amplifies a line level signal to a speaker level signal.

Power Amp Protection - Reference DC Fault Protection, Overcurrent Protection, and Overtemprature Protection.

Release - The time it takes for the compressor or limiter to return the level of the output signal to the level of the original input signal once it has passed below the threshold.

Speaker Driver - A transducer that converts electrical energy into sound waves. Common names for the different types of speaker drivers are: woofer, mid-range, and tweeter.

Thermal Limiting - Regulatory protection over the temperature of a loudspeaker’s voice coil to prevent the loudspeaker’s magnet from being overheated.

Threshold - The audio level set by user at which the compressor or limiter will be activated when the audio signal exceeds it.

Transducer Protection - Reference Excursion Limiting and Thermal Limiting.

Transient - A temporary, short-lived signal with a higher amplitude than the rest of the signal - a ‘spike’ in the signal.

Triamplified system - A loudspeaker system with a crossover and three power amplifiers, each handling their own third of the frequency spectrum.


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