Audio Glossary

The audio glossary has definitions relating to various aspects of audio production. To quickly navigate to a specific definition, either use the search box below, or click on one of the initial letters of the A to Z below.

A-B-C-D-E-F-G-H-I-L-M-N-O-P-Q-R-S-T-U-V-W-X-Y

A

Absorption - The dissipation of sound energy through absorbent materials.

Acoustics - The science of the transmission of sound waves. Generally refers to the characteristics of auditoriums, theatres and studios with respect to their design.

Acoustic Treatment - Controlling the behaviour of sound waves through a variety of methods.

Active Circuitry - Electrical circuitry which requires power to operate, such as transistors.

Ambience - Room acoustics or natural reverberation.

Amplitude - The strength or level of sound pressure or voltage.

Analogue - An electrical signal whose frequency and level vary continuously in direct relationship to the original electrical or acoustical signal.

Analogue Recording - A means of recording audio whereby the recorded signal is a physical representation of the waveform of the original signal. Vinyl is an example of analogue recording.

Attack - The initial part of a sound or the way something effects the initial part of a sound.

Attenuate - To reduce in level.

Audio Chain - The series of interconnected audio equipment used for recording or PA.

Audio Frequency - Signals in the human audio range. Measured in Hertz (Hz).

Audio Interface - A device that has numerous audio inputs and outputs.

Audiophile - A person who is overly interested in sound reproduction.

Auditory Area - The sensory area lying between the threshold of hearing and the threshold of feeling or pain.

B

Background Noise - Noise from all sources unrelated to a particular sound that is the object of interest. Background noise may include airborne, structure borne, and instrument noise.

Backplate - The solid conductive disk that forms the fixed half of a condenser element within a condenser microphone.

Baffle - Moveable barrier used to achieve separation of signals from different sources or the surface or board upon which a loudspeaker is mounted.

Balanced - A circuit that carries information by means of two equal but opposite polarity signals, on two conductors. Balanced cables reduce susceptibility to internal and external noise.

Bandpass Filter - A filter that attenuates signals both below and above the desired passband.

Bandwidth - The range of frequencies in a signal.

Bass - The lower range of audible frequencies (60-250Hz).

Bass Roll Off Filter - Rolls away low frequencies of a signal to achieve a more balanced sound.

Beats - Periodic fluctuations that are heard when sounds of slightly different frequencies are superimposed.

Bidirectional Microphone - A microphone that picks up equally from two opposite directions. The angle of best rejection is 90 deg. from the front (or rear) of the microphone, that is, directly at the sides.

Binary - Number system comprising of ones and zero (digital).

Binaural - A situation involving listening with two ears.

Bleed - Leakage of sound into other microphones.

Boost - To increase, make louder or brighter; opposite of attenuate.

Boundary - The line or plane indicating the limit or extent of something.

Boundary/Surface Microphone - A microphone designed to be mounted on an acoustically reflective surface.

Boomy - Listening term. Refers to an excessive bass response.

Boxy - Listening term. Refers to the excess upper-bass/lower-midrange response of cabinet-wall resonances.

Bright - Listening term. Usually refers to the upper frequency energy.

C

Capacitance - An electrical component's ability to store electrical charges.

Capacitor - An electronic device which stores energy and releases it when needed.

Cardioid Microphone - A unidirectional microphone with moderately wide front pickup (131 deg.). Angle of best rejection is 180 deg. from the front of the microphone, that is, directly at the rear.

Cartridge (Transducer) - The element in a microphone that converts acoustical energy (sound) into electrical energy (the signal).

Cavity - A space between two walls where insulation is typically installed.

Channel Strip - The physical representation of an audio channel on the front panel of a mixer; usually a long, vertical strip of controls.

Close Pickup - Microphone placement within 1 metre of a sound source.

Clipping - Refers to a type of distortion that occurs when an amplifier is driven into an overload condition. Usually the "clipped" waveform contains an excess of high-frequency energy. The sound becomes hard and edgy.

Coloration - Listening term. A colored sound characteristic adds something not in the original sound. The coloration may be euphonically pleasant, but it is not as accurate as the original signal.

Comb Filtering - An interference effect in which the frequency response exhibits regular deep notches.

Compression - The reduction of a span of amplitudes done for the purpose of limiting the reproduction of those amplitudes.

Condenser Microphone - A microphone that generates an electrical signal when sound waves vary the spacing between two charged surfaces: the diaphragm and the backplate.

Constructive Interference - Addition of two or more waves when wave crests overlap to produce a resulting wave of increased amplitude.

Critical Distance - In acoustics, the distance from a sound source in a room at which the direct sound level is equal to the reverberant sound level.

Crossover Frequency - In a loudspeaker with multiple radiators, the crossover frequency is the 3dB point of the network dividing the signal energy.

Current - Charge flowing in an electrical circuit. Analogous to the amount of a fluid flowing in a pipe.

Cycles Per Second - The frequency of an electrical signal or sound wave. Measured in Hertz (Hz).

CV - Abbreviation of Control Voltage. CV is used to control various modules in a synthesiser.

D

DAW (Digital Audio Workstation) - A computer-based recording and editing machine used for manipulating sounds.

Decay - The term used to describe the progression of reduction in amplitude of a sound or electrical signal over time.

Decibel (dB) - A number used to express relative output sensitivity. It is a logarithmic ratio.

Destructive Interferance - Combination of waves where crest parts of one wave overlap trough parts of another; resulting in a wave of decreased amplitude.

Diaphragm - The thin membrane in a microphone which moves in response to sound waves.

Diffraction - The bending of sound waves around an object which is physically smaller than the wavelength of the sound.

Digital - A reference to a system whereby a continuously variable analog signal is reduced and encoded into discrete binary bits that establish a mathematical model of an original signal or other information.

Direct Sound - Sound which travels by a straight path from a sound source to a microphone or listener.

Directional Microphone - A microphone that detects and transmits sound from only a certain direction

Distance Factor - The equivalent operating distance of a directional microphone compared to an omni-directional microphone to achieve the same ratio of direct to reverberant sound.

Distant Pickup - Microphone placement farther than 2 feet from the sound source.

Distortion - Anything that alters the musical signal. There are many forms of distortion, some of which are more audible than others.

Dynamic Microphone - A microphone that generates an electrical signal when sound waves cause a conductor to vibrate in a magnetic field. In a moving-coil microphone, the conductor is a coil of wire attached to the diaphragm.

Dynamic Processor - A dynamic processor is a device that changes an audio signal by adjusting the dynamic content of the sound being worked on.

Dynamic Range - The difference in decibels between the loudest and quietest portions of audio.

E

Echo - Reflection of sound that is delayed long enough (more than about 50 msec.) to be heard as a distinct repetition of the original sound.

Electret - A material (such as Teflon) that can retain a permanent electric charge.

Ensemble - Musicians must hear each other to function properly; in other words ensemble must prevail. Diffusing elements surrounding the stage area contribute greatly to ensemble.

Envelope - The shape of the graph as amplitude is plotted against time. A sound's envelope includes its attack, decay, sustain and release.

Equalizer - Audio device with multiple frequency controls for adjusting sound tone quality.

Equalization - Equalization or tone control to shape frequency response in some desired way.

F

Feedback - Feedback occurs when a sound loop exists between an audio input, for example, a microphone, and an audio output for example, a loudspeaker

loudspeaker entering the microphone and being re-amplified.

Fidelity - As applied to sound quality, the faithfulness to the original.

Filter - A type of powerful tone-shaping network used by synthesisers to create tonal sweeps and changes.

Flat Response - A frequency response that is uniform and equal at all frequencies.

Fletcher-Munson Curve - Our sensitivity to sound depends on its frequency and volume. Human ears are most sensitive to sounds in the midrange. At lower volume levels humans are less sensitive to sounds away from the midrange, bass and treble sounds "seem" reduced in intensity at lower listening levels.

Flutter - A repetitive echo set up by parallel reflecting surfaces.

Frequency - The number of times a signal vibrates each second as expressed in cycles per second (cps) or Hertz (Hz).The higher the frequency the higher the pitch.

Frequency Response - A graph showing how a microphone responds to various sound frequencies; It is a plot of electrical output (in decibels) vs. frequency (in Hertz).

Frequency Response Tailoring Switch - A switch on a microphone that affects the tone quality reproduced by the microphone by means of an equalization circuit. (Similar to a bass or treble control on a hi-fi receiver.)

Fundamental - The lowest frequency component of a complex waveform such as musical note. It establishes the basic pitch of the note.

G

Gain - The ratio of the signal level at the output of an audio device to the signal level at its input. Expressed in decibels (dB).

Gain Before Feedback - The amount of gain that can be achieved in a sound system before feedback or ringing occurs.

Grain - Listening term. A sort of "grittiness" added to the sound.

H

Harmonic - Frequency components above the fundamental of a complex waveform. They are generally multiples of the fundamental which establish the timbre or tone of the note.

Headroom - The ability of an amp to go beyond its rated power for short durations in order to reproduce musical peaks without distortion. This capability is often dependent on the power supply used in the design.

Headphone Mix - A separate mixed sound which is set up just for headphones.

Hearing Sensitivity -The human ear is less sensitive at low frequencies than in the midrange. Turn your volume knob down and notice how the bass seems to "disappear". To hear low bass requires an adequate SPL level. To hear 25Hz requires a much higher SPL level than to hear 250Hz.

Hertz (Hz) - Unit for measuring frequency of d signal; formerly called "cycles per second."

High-Pass Filter - An electronic filter used in various audio circuits to attenuate all frequencies below a chosen frequency.

Hypercardioid - A hypercardiod is a unidirectional microphone with tighter front pickup (105 deg.) than a supercardioid, but with more rear pickup. Angle of best rejection is about 110 deg. from the front of the microphone.

I

Impedance - In an electrical circuit, opposition to the flow of alternating current, measured in ohms. A high impedance microphone has an impedance of 10,000 ohms or more. A low impedance microphone has an impedance of 50 to 600 ohms.

Interference - Destructive combining of sound waves or electrical signals due to phase differences. - States that direct sound levels increase (or decrease) by an amount proportional to the square of the change in distance.

Inertia - The tendency of an object at rest to remain at rest, and of an object in motion to remain in motion.

Inverse Square Law - States that direct sound levels increase (or decrease) by an amount proportional to the square of the change in distance; the sound pressure level decreases 6 dB for each doubling of the distance.

Isolation - Freedom from leakage; ability to reject unwanted sounds.

L

Latency - Delay that occurs between a MIDI keyboard being played and the sound appearing at the output soundcard or interface.

Leakage - Pickup of an instrument by a microphone intended to pick up another instrument. Creative leakage is artistically favourable leakage that adds a “loose” or “live” feel to a recording.

Level - The ratio of an acoustic quantity to a reference quantity. A measurement of amplitude in decibels.

Listening Fatigue - A psychoacoustic phenomenon from prolonged listening to sound whose distortion content is too low to be audible as such but is high enough to be perceived subliminally.

Loudness - A subjective term for the sensation of the magnitude of sound. The subjective response to a sound level.

Loudspeaker - An electroacoustical transducer that changes electrical energy to acoustical energy.

Lowpass Filter/Low Frequency Roll Off Switch - A filter that attenuates frequencies above a specified frequency and allows those below that point to pass.

Low Frequency - The lower range of audible frequencies.

Low Frequency Oscillator - An oscillator used as a modulation source. The most common LFO waveshape is the sine wave.

M

Masking - The amount (or the process) by which the threshold of audibility for one sound is raised by the presence of another (masking) sound.

Microphone - An acoustical-electrical transducer by which sound waves in air may be converted to electrical signals.

MIDI - Musical Instrument Digital Interface. A machine protocol that allows synthesizers, computers, drum machines and other processors to communicate with and/or control one another.

Midrange - A speaker, (driver), used to reproduce the middle range of frequencies. A midrange is combined with a woofer for low frequencies and a tweeter for high frequencies to form a complete, full-range system

Millisecond - One thousandth of a second, abbreviated ms or msec

Mixer - A mixer is a device that allows several different audio sources to be combined. It provides independent control over each signal's loudness, tone and stereo position.

Modulation - The process of sending a control signal to a sound source so as to change the character of the sound.

Monitor - Loudspeaker used in the control of a recording studio.

Monophonic - Single channel/note sound.

Muddy - Listening term. A sound that is poorly defined, sloppy or vague. For example, a "muddy" bass is often boomy with all the notes tending to run together.

Muting - To greatly decrease the volume level. Many receivers and pre-amplifiers have a muting control which allows the volume level to be cut way down without changing the master volume control. Great for when the phone rings.

N

NAG - Needed Acoustic Gain is the amount of gain that a sound system must provide for a distant listener to hear as if he or she was close to the unamplified sound source.

Near Field - Locations close to the sound source between the source and the far field. The near field is typically characterized by large sound pressure level variations with small changes in measurement position from the source.

Noise - In audio systems, noise is the electrical interference or other unwanted sound introduced into the system (i.e. hiss, hum, rumble, crosstalk, etc).

Noise Canceling - A microphone that rejects ambient or distant sound.

O

Octave - An octave is a doubling or halving of frequency. 20Hz-40Hz is often considered the bottom octave. Each octave you add on the bottom requires that your speakers move four times as much air.

Octave Bands - Frequency ranges in which the upper limit of each band is twice the lower limit.

Octave bands are identified by their geometric mean frequency, or center frequency.

Omnidirectional Microphone - A microphone that picks up sound equally well from all directions.

Oscillator - Circuit designed to generate a periodic electrical waveform.

Overload - Exceeding the signal level capability of a microphone or electrical circuit.

Overtone - Tones of higher pitch that are present in every musical sound and whose presence determines the quality of the musical sound.

P

PAG - Potential Acoustic Gain is the calculated gain that a sound system can achieve at or just below the point of feedback.

Particle - A body having finite mass and internal structure but negligible dimensions

Phantom Power - A method of providing power to the electronics of a condenser microphone through the microphone cable.

Phase - The “time” relationship between cycles of different waves.

Phase Cancellation - Undesirable dips and peaks in frequency response caused by mixing the outputs of two microphones which are picking up the same sound but with different arrival times.

Phasing - The hollow sound that occurs when two identical waves combine.

Pickup Angle / Coverage Angle - The effective arc of coverage of a microphone, usually taken to be within the 3dB down points in its directional response.

Pitch - The fundamental or basic frequency of a musical note.

Pitch Blend - A control message designed to produce a change in pitch in response to the movement of a special wheel.

Plug In - A piece of software designed to add capabilities and features to a host system.

Polar Pattern (Directional Pattern, Polar Response) - A graph showing how the sensitivity of a microphone varies with the angle of the sound source, at a particular frequency. Examples of polar patterns are unidirectional and omnidirectional. in an electrical circuit. It is analogous to the friction of fluid flowing in a pipe.

Polarization - The charge or voltage on a condenser microphone element.

Polyphony - Term to describe the ability of an instrument to play two or more notes simultaneously.

Pop Filter/Shield - An acoustically transparent shield around a microphone cartridge that reduces popping sounds. Often a ball-shaped grille, foam cover or fabric barrier.

Portamento - Gliding effect that allows a sound to change pitch at a gradual rate rather than abruptly when a new pitch is pressed.

Pop - A thump of explosive breath sound produced when a puff of air from the mouth strikes the

microphone diaphragm. Occurs most often with “ p,” “t,” and “b” sounds.

Presence Peak - An increase in microphone output in the “presence” frequency range of 2000 Hz to 10,000 Hz. A presence peak increases clarity, articulation, apparent closeness, and “punch.”

Preamplifier - An electronic device that boosts extremely weak signal voltages, such as those from microphones, to a level that is usable by power amplifiers.

Proximity Effect - The increase in bass occurring with most unidirectional microphones when they are placed close to an instrument or vocalist (within 1 ft.). Does not occur with omnidirectional microphones.

Q

Q - Measure of the resonant properties of a filter. The higher the Q, the more resonant the filter and the narrow therangeof frequencies that are allowed to pass.

Quantise - The term used to describe the facility present on sequences that allows notes to be snapped to a user defined subdivision of a bar of music - for example, 8th notes. Quantise is usually used to correct timing errors.

R

Rarefraction - The opposite of an area of compression in a longitudinal wave; the reduction of a airs density.

Rear Lobe - A region of pickup at the rear of a supercardioid or hypercardioid microphone polar

pattern. A bidirectionalmicrophone has a rear lobe equal to its front pickup.

Reflection/ Reflected Sound - The bouncing of sound waves back from an object or surface which is physically larger than the wavelength of the sound.

Refraction - The bending of sound waves by a change in the density of the transmission medium, such as temperature gradients in air due to wind.

Release - Rate at which a signal amplitude decays once a key has been released.

Resistance - The opposition to the flow of current in an electrical circuit. It is analogous to the friction of fluid flowing in a pipe.

Resonant Frequency - A natural frequency of vibration determined by the physical parameters of the vibrating object.

Resonance:-

  1. Characteric of a filter that allows it to pass a narrow range of frequencies.
  2. The tendency of a system to absorb more energy when the frequency of the oscillations matches the system's natural frequency of vibration (its resonant frequency) than it does at other frequencies.

Reverberation - The reflection of a sound a sufficient number of times that it becomes non-directional and persists for some time after the source has stopped. The amount of reverberation depends on the relative amount of sound reflection and absorption in the room.

Rhythm - The regular or ordered repetition of dominant and subordinate elements within music.

Rolloff - A gradual decrease in response below or above some specified frequency.

S

Sawtooth wave - Waveform that resembles the teeth of a saw, containing only even harmonics.

Sensitivity - The electrical output that a microphone produces for a given sound pressure level.

Sequencer - A program that records and plays back user-determined sets of audio and MIDI data. Most sequencers also allow the data to be edited in various ways, and stored on disk.

Shaped Response - A frequency response that exhibits significant variation from flat within its range. It is usually designed to enhance the sound for a particular application.

Sibilance - An exaggerated hissing in voice patterns.

Signal-To-Noise Ratio - The range or distance between the noise floor (the lowest audible level) and the music signal.

Sine Wave - Waveform of a pure tone which contains no harmonics.

Slap Back - A discrete reflection from a nearby surface.

Sound Chain - The series of interconnected audio equipment used for recording or PA.

Sound Pressure Level - A measure of the strength or intensity of a sound, rated in decibels.

Sound Proofing - Building materials that makes structures impervious to sound or insulates against sound.

Sound Reinforcement - Amplification of live sound sources.

Spaced Pair - Two separate microphones that are placed some distance apart, aiming straight ahead toward the sound source. The greater the spacing between mics, the greater the stereo spread.

Sparkle - Listening term, refers to the brilliance/high frequency content of a sound.

Spectral Balance - Balance across the entire frequency spectrum of the audio range.

Spectrum -The distribution of energy as a function of frequency for a particular sound source

Specular Reflections - Mirrorlike reflections of sound (angle of incidence equals angle of reflection) from a flat surface. Reflections that do not spread out.

Speed of Sound - The speed of sound waves, about 1130 feet per second in air.

Spill - Acoustic interference from unwanted source sounds.

SPL - Sound Pressure Level is the loudness of sound relative to a reference level of 0.0002 microbars.

Standing Wave - A stationary sound wave that is reinforced by reflection between two parallel surfaces that are spaced a wavelength apart.

Stereophonic - From the Greek meaning solid. Audio split on two physical tracks, one on the right and one on the left. The purpose of stereo is not to give you separate right and left channels, but to provide the illusion of a three-dimensional, holographic image between the speakers.

Stereo Image - The spread of sound received from two speakers.

Square Wave - Symmetrical, rectangular waveform which contains a series of odd harmonics.

Subwoofer - A speaker designed exclusively for low-frequency reproduction. A true subwoofer should be able to at least reach into the bottom octave (20-40Hz). There are many "subwoofers" on the market that would be more accurately termed "woofers".

Super Cardioid Microphone - A unidirectional microphone with tighter front pickup angle (115 deg.) than a cardioid , but with some rear pickup. Angle of best rejection is 126 deg. from the front of the microphone, that is, 54 deg. from the rear.

T

Tempo (Italian for "time") - Tempo is the speed or pace of a given piece.

Three To One Rule - When using multiple microphones, the distance between microphones should be at least 3 times the distance from each microphone to its intended sound source.

Timbre - The characteristic tone of a voice or instrument; a function of harmonics.

Transducer - A device that converts one form of energy to another. A microphone transducer (cartridge) converts acoustical energy (sound) into electrical energy (the audio signal).

Transient Response - The ability of a device to respond to a rapidly changing input.

Treble - The highest part, voice, instrument, or range.

Tremolo - Modulation of the amplitude of a sound carried out be an LFO.

Tone - A tone results in an auditory sensation of pitch.

Transients - Instantaneous changes in dynamics, producing steep wave fronts.

Transparency - Listening term. An analog that can be best "pictured" in photography. The more "transparent" the sound, the clearer the auditory picture.

U

Unbalanced - A circuit that carries information by means of one signal on a single conductor.

Unidirectional Microphone - A microphone that is most sensitive to sound coming from a single direction-in front of the microphone. Cardioid, supercardioid, and hypercardioid microphones are examples of unidirectional microphones.

V

Velocity - Term used to describe the rate at which a key is depressed.

Vibrato - Pitch modulation performed by an LFO to control a VCO.

Voltage - The potential difference in an electric circuit. Analogous to the pressure on fluid flowing in a pipe.

Volume - Colloquial equivalent of sound level.

VU Meter - A meter designed to measure audio level in volume units which generally correspond to perceived loudness.

W

Warmth - A listening term. The opposite of cool or cold. In terms of frequency, generally considered the range from approx

Wave - A regular variation in electrical signal level or sound pressure level.

Waveform - A graphic representation of the shape of a sound wave. The waveform determines some of the physical characteristics of the sound.

Wavelength - The physical distance between the start and end of one cycle of a soundwave.

X

XLR - One of several varieties of sound connectors having three or more conductors plus an outer shell which shields the connectors and locks the connectors into place

Y

X-Y Pattern - A pair of cardioid microphones or elements aimed in crossed directions which feed two channels for stereo pickup.