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Acappella - A piece of music which consists only of voice or voices and lacks instrumental accompaniment. In recent use "an Acapella" has come to represent an audio file of the vocal content from a commercial track (usually in Mp3 format) with many sample download websites offering Acapella sample packs.

A/D Conversion / Converter - Analogue to Digital conversion. A converter is a device which achieves this. The quality of conversion is highly dependent on the amount of bits used in the conversion process, hence a 24 bit converter will achieve a much more accurate resolution of the sound than say, an 8 bit converter. Many sound engineers prefer to use high quality stand-alone convertors rather than those found on standard sound cards.

AAC (.aac) - "Advanced Audio Coding", an audio codec developed by Fraunhofer that seeks to preserve audio quality at lower bitrates.

Acoustics - The study of sound and its behavior within a given environment.

Active - Describes a circuit containing components that require power to operate, and are capable of amplification. "Active" loudspeakers (i.e. those with a built amp) have become the standard for studio use.

Additive Synthesis - A method of synthesis that builds complex waveforms by combining sine waves with independently variable frequencies and amplitudes. Envelope shapers and filters can further process these waveforms. Hammond organs and similar instruments make the most use of simple additive synthesis.

ADSR - Attack, Decay, Sustain and Release are the four stages of an envelope that describe the shape of a sound over time.

  • Attack represents the time the sound takes to rise from an initial value of zero to its maximum level.
  • Decay is the time for the initial falling off to the sustain level.
  • Sustain is the time during which it remains at this level.
  • Release is the time it takes to move from the sustain to its final level.

Attack, Decay, and Release parameters are rate or time controls. Sustain is a level. When a key is pressed, the envelope generator will begin to rise to its full level at the rate set by the attack parameter, upon reaching peak level it will begin to fall at the rate set by the decay parameter to the level set by the sustain control. The envelope will remain at the sustain level as long as the key is held down. When a key is released, it will return to zero at the rate set by the release parameter. Read our tutorial on using filters featuring envelopes here.

Aftertouch - A MIDI controller, describes the pressure applied to a synthesiser keyboard after the key is depressed.

AIFF - Audio Interchange File Format , developed by Apple for storage of sounds, very similar to .Wav format.

Algorithm - A computer program designed to perform a specific task.

Aliasing - A type of distortion that occurs when digitally recording high frequencies with a low sample rate. A visual analogy can be found in video, when a car's wheels appear to slowly spin backwards while the car is quickly moving forward. Similarly when you try to record a frequency greater than one half of the sampling rate (Nyquist Frequency), instead of hearing a high pitch you may hear a low frequency rumble. An anti-aliasing filter can be used to remove high-frequencies before recording. However, once a sound has been recorded, aliasing distortion is impossible to remove without also removing other frequencies from the sound.

Ambience - The reverberant quality of a room . The result of sound reflections in a confined space being added to the original sound. Ambience may also be created electronically by some digital reverb units. The main difference between ambience and reverberation is that ambience doesn't have the characteristic long delay time of reverberation - the reflections mainly give the sound a sense of space.

Amplifier- A device the increases the magnitude of a voltage or current with out distorting the wave form of the signal. An amplifier takes a weak signal from a line level or mike level source and provides the necessary power level to operate loudspeakers.

Attenuate - To reduced in volume.

Analog Synthesis- electronic oscillators, filters, and envelopes are used to directly create and manipulate sound. It does not involve sampling rate, bit depth, or other digital factors. (Such as older Analog Synthesizers/Keyboards used in the 1970s, e.g Moog). A synthesizer which uses voltage controlled analog modules to synthesize sound. The three main voltage controlled modules in an analog synthesizer are: Voltage Controlled Oscillator (VCO), Voltage Controlled Filter (VCF), and Voltage Controlled Amplifier (VCA).

Arpeggiate - To play the notes of a chord in succession rather than simultaneously. An Arpeggiator ia a device that sequentially plays a pattern of notes over a range of the keyboard. The speed of the arpeggiation and pattern of notes are variable depending on the tempo and specified/pressed notes. Device (or software), that allows a MIDI instrument to sequence around any notes currently being played. Most arpeggiators also allows the sound to be sequenced over several octaves, so that holding down a simple chord can result in an impressive repeating sequence of notes. Many soft synths have built in Arpeggiators.

Attack - The initial time period of an envelope during which a sound's attribute (such as volume) increases from 0 (silence) to it's maximum amount. The length of the attack determines how "soft" or "harsh" a sound is. For example, most drum or percussion sounds have a short attack time and thus have a sudden "harsh" start. A string sound usually has a long attack time and thus has a "soft" start and eases in.

Audio Unit (AU) - Apple's system level audio plugin format.


Baffle (Acoustic) - The part of a loudspeaker enclosure on to which the driver units are fastened. Alternatively, a sound absorbent barrier used in recording studios to separate musicians who are recording in the same room.

Balanced / Balanced Line - An audio cable, most commonly a three pin "XLR" type mic cable or TRS jack, which has two conduction channels surrounded by metallic shielding where each conductor is of equal impedance relative to the ground/ earth. The conductors should have equal potential but opposite polarity. The advantage of this system is in terms of noise reduction, as a balanced line reduces unwanted noise because the opposing polarities ensures that unwanted noise is lost through cancellation effects when the inverted signal on one conductor is added to the original signal of the second conduction channel when the whole of the signal reaches it's destination.

Band Pass Filter - A filter which allows only certain audio frequencies to pass, while rejecting all others above and below the cutoff points. An example of a bandpass filter may be found in a "3 - way" loudspeaker system which will utilise a "woofer" for bass frequencies, a "midrange" unit for middle frequencies, and a "tweeter" for high frequencies. Whilst the woofer (which has no frequencies below it) will be able to have it's band of frequencies fed to it via a "low pass" filter and the "tweeter" which has no frequencies above it will have a high pass filter, the midrange, which will have frequencies both above and below it's area of operation will need to have its frequencies fed to it via a bandpass filter. Read our tutorial on using filters here

Bandwidth- The upper and lower limits of a range of frequencies a signal possesses, or that a piece of equipment will pass. It should not be confused with frequency response, which concerns itself not only with the upper and lower limits but also how frequencies are amplified or attenuated between these two points.

Bank - a storage location in a sampler or synthesizer that typically holds a large number of individual program (sounds).

Bias- High frequency signal used in analogue recording to improve the accuracy of the recorded signal and to drive the erase head.

Bit/Bit-Depth - often used to describe the resolution or quality of each sample in a digital audio stream. It is the number of bits (0's and 1's) used to describe the amplitude or volume of an audio signal at a specific point in time. The higher the number, the more precisely the original or intended audio signal can be (re)produced. See Digital Audio Basics for a more detailed explanation.

Bit - Smallest unit of digital currency, and the basis of the binary numbering system (bit is a shortening of "binary digit). A bit may be either 0 (off), or 1 (on). Eight bits make a Byte (see below). A Bit is a single piece of information assigned a value of 0 or 1 as used in a digital computer. Computers use digital words which are combinations of bits. A Byte is a digital word consisting of eight Bits.

Bit Rate- The speed at which audio data travels per second.

BPM- Beats per minute.

Breakbeat - A genre of music derived from sampled drum loops such as that from The Winston's "Amen, Brother" and James Brown's "Funky Drummer".

Bus - A bus is one of the main outputs of a mixer, which may be connected to one of inputs of a recorder, amplifier or signal processor. I

Buffer- A temporary storage area in memory.


Cardioid (unidirectional)- A microphone pickup pattern that is characterised by the shape of a "love heart" emanating from the capsule of the microphone. It should display a high sensitivity to sounds which are produced in front of the capsule, and a very low sensitivity to sounds which are produced behind it. There are also Supercardioid and Hypercardioid pickup patterns which are similar, but have a narrower pattern at the front, and a little more sensitivity at the rear.

.cda - not a file format but a way of displaying audio tracks, much like a menu.

CD Text - disc and track information embedded on an audio CD

CD-R (compact disc-recordable)- A blank disc that can be loaded with sound recordings by technology available for use on a personal computer. Recordable type of Compact Disc that can only be recorded once - it cannot be erased and reused.

Channel- A channel is a path for passing data or digital audio. In the context of mixing consoles, a channel is a single strip of controls relating to one input.

Chorus - A doubling effect commonly found on a synthesiser or sampler that makes a single sound appear to sound like an entire ensemble. The initial signal is split and appears at a slightly altered pitch from the original, or at a slightly later point in time. This time and pitch level are often controllable by a low frequency oscillator (LFO).

Chromatic Scale- A musical scale in which notes are incremented in semitones.

Circuit Bending - The creative short-circuiting of low voltage battery operated devices such as children’s toys, small synthesisers and guitar peddles to produce new musical instruments and sound generators. Notable users of this technique include Kraftwerk, Aphex Twin, Nine Inch Nails and Renegade Hardware.

Clipping - When the amplitude of a signal exceeds the maximum possible level of a device, the part of the waveform which is excessive is "clipped" resulting in a distortion of the sound. If clipping is harsh and prolonged, this can result in damage to the device in question. See also "Headroom". Distortion occurs when an amplifier is driven to play louder than its power supply allows and the result is clipping. This state can cause loudspeaker damage. It is of particular importance with digital audio recording because the clipped waveform contains an excess of high-frequency energy and the sound becomes hard and edgy. With analog linear recording it is standard to record as hot as possible; with digital non-linear recording, recording too hot will result in disastrous clipping.

Clock- A clock is used to synchronize two devices. In MIDI, the term clock is used to denote a single time source, which everything plays along with. MIDI clocks are actually special messages that are sent 24 times (normally) per beat, and are used to synchronize two sequencers, or a sequencer and a drum machine. Normally, the sequencer's clock is the important one. Other clock sources are rarely used, and, typically, only when doing a final recording.

Codec - Stands for coder/decoder. Codecs are often used by software to compress and decompress audio data. For example, most Windows computers have an ADPCM codec which many software applications use to read and write compressed audio data from ADPCM compressed WAV files. You can view the codecs installed in Windows by going to Control Panel > Multimedia > Devices Tab > Audio Compression Codecs.

Compression- Compression in audio recording means to reduce the dynamic range of a signal. This usually means amplifying lower level signals, resulting in a sound that is perceived as louder and more "punchy"), the reverse of this is "expansion" see Dynamics Processing. A compressor provides a form of automatic level control. It attenuates high levels, thereby reducing the dynamic range, making it easier to control signals and set appropriate fader levels. Limiting is an extreme form of compression, where the output signal is sharply attenuated so that it cannot exceed a particular level. Read our tutorial on compression here

Condenser or Capacitor Microphone - A microphone that generates an electrical signal when sound waves vary the spacing between two charged surfaces, specifically the diaphragm and the backplate. Condenser microphones offer the greatest fidelity in terms of traducing sound waves into an electrical signal, however, they do have the disadvantages mentioned above, as well as a great sensitivity to picking up hums/ ground loops etc, and a delicacy which renders many of them more suitable for studio, rather than stage use. Even then, many of them have to be used in conjunction with a special "cradle" or shock mount which protects them from vibrations and other influences.

Controller- MIDI device that sends performance information (not necessarily sounds).

Count in- A command in a sequencer that plays a metronome for several measures until you are ready to record.

Crossfade- To gradually fade out one sound while fading in another so that a seamless transition is made between the two sounds.

Crossover (Electronic)- An electronic device or circuit that, when inserted between a mixer and amplifier, divides the audio spectrum into individual frequency ranges (low, high, and/or mid) before sending them to specialized amplifier/speaker combinations. In many computer speakers, a crossover routes high-frequency sounds to satellite modules and low frequencies to the bass unit. An advantage of this type of crossover is that it increases efficiency. / Crossover network: - As most loudspeaker systems use two or more specialized drive units which individually only cover a part of the frequency spectrum ("woofer" for bass frequencies "tweeter" for treble etc), some kind of circuit is needed to separate the bands of frequencies which are appropriate for each of the drive units, this is a crossover. There are two primary ways of doing this.

Crossover Frequency- The frequency in which the audio signal is divided by a crossover.

Cursor: A visual indicator showing the position of the next entry.

Cut And Paste Editing- The ability to copy or move sections of a recording to new locations. Read our guide to basic audio editing here.

Cut- To remove something, either a sound or a segment, by selecting it and choosing the cut function from the module menu. What you cut is placed on the clipboard.

Cutoff Frequency- The frequency above or below which attenuation begins in a filter.

CV- Control voltage used in analogue synthesizers, to control oscillator or filter frequency. Control Voltage used to control the pitch of an oscillator or filter frequency in an analogue synthesizer. Most analogue synthesizers follow a one volt per octave convention, though there are exceptions. To use a pre-MIDI analogue synthesizer under MIDI control, a MIDI to CV converter is required.

CYCLE- One complete vibration of a sound source or its electrical equivalent. One cycle per second is expressed as 1Hertz (Hz).


D.A.T. - Acronym of Digital Audio Tape.

D/A Conversion / Converter- Digital to Analogue conversion. A converter is a piece of circuitry which achieves this. The quality of conversion is highly dependent on the amount of bits used in the conversion process, hence a 24 bit converter will achieve a much more accurate resolution of the sound than an 8 bit converter.

Daisy Chain- A group of devices or modules connected to each other in a series, where the first one connects to the computer, the second one connects to the first and so on. This would include SCSI, USB and FireWire connectivity.

dB- (Decibel) A unit used for measuring two voltages, currents or powers. The decibel is often used to measure differences in sound pressure level (relative loudness).

Decay- The period of an envelope during which a sound's attribute (such as volume) stabilizes after the attack has completed. When the sound attribute reaches the end of it's decay, it has reached the sustain period. The progressive reduction in amplitude of a sound or electrical signal over time. In the context of an ADSR envelope shaper, the Decay phase starts as soon as the Attack phase has reached its maximum level. In the Decay phase, the signal level drops until it reaches the Sustain level set by the user. The signal then remains at this level until the key is released, at which point the Release phase is entered.

Decoding - Making a format readable. MP3 players "decode" MP3 by being able to play the data format as audio. However, the term usually refers to the process of converting MP3 to WAV . This is the process whereby information in a compressed digital audio file is read/expanded so that it can be converted from digital to analog to go to speakers so we can hear. There are software MP3 players that both decode and play MP3 files.

De-esser- Signal processing device used to cut down on the sibilance or "hissy s's" which can sometime affect speech and singing through a microphone. This is usually through use of the techniques of high frequency compression combined with equalisation.

Default- The set of conditions (parameters) with which a computing device or application starts out when first turned on or "booted up". It applies both to software and hardware, musical and non-musical conditions.

Delay - a common effect in a sampler or synthesizer that mimics the time difference between the arrival of a direct sound and the first reflection to reach the listener's ears. An effect that is used to add depth or space to an audio signal by repeating the input one or more times after a brief pause of a few milliseconds to a few seconds. Delay is also often referred to as echo (a device which will repeat sound at regular intervals producing echo-like effect).

Digital- The use of Binary data to represent information, "Binary" meaning that the data (audio, video, whatever) has been reduced to many values which have one of two states, positive and non positive. Positive is represented by 1, and non positve by 0. Each value is known as a "bit". For more on "Digital" within an audio context, see Sample. Equipment that uses quantities represented as binary numbers. In a digital synthesizer every aspect of the sound generation is handled as a numeric calculation. The digital information is not audible and so must be converted to analog form by a DAC before it is output. The phrase “digital audio recording” is contrasted with “analog audio recording.” Long-playing phonograph records are analog recordings and they capture information in a continuously-variable form. Digital, in contrast, involves binary numbers--1's and 0's. Digital encoding can “think” only in terms of the binary numbers 1 (on) and 0 (off), therefore a synthesizer produces sounds by performing mathematical manipulations upon a stream of numbers which are then transformed by a digital-to-analog converter to an electrical signal. In analog there is no conversion taking place, but every time you copy or boost there can be added noise or loss of original content with each pass which does not happen with digital.

Digital Audio- the numeric representation of sound. Typically used as the means for storing sound information in a computer or sampler. Read our guide to basic audio editing here.

Digital Audio Extraction- A method of retrieving audio samples from an audio CD in order to create a computer audio file. This is also known as ripping. This can be accomplished at “CD” quality or MP3 quality MP3, being a digital compression format, will take up less space than a “CD” quality file on a computer audio file.

Distortion- a process often found desirable by guitar players, that alters a sound's waveform.

Dither- A system of adding low level noise to a digitized audio signal in such a way as to extend to the low level resolution at the expense of a slight deterioration in noise performance. This tool is used with high-end audio recording programs and audio converters to improve audio quality. It is a mathematical process where a random noise is added to the least significant bit of a digital word to improve audio fidelity when needed. The ability to dither an audio file is absolutely required for good digital audio recording and audio editors such as Sonic Foundry’s Sound Forge and Steinberg’s Wavelab have excellent dithering capabilities.

Drum machine- an electronic device, usually controllable via MIDI commands, that contains samples of acoustic drum sounds. Used to create percussion parts and patterns. A sample based digital audio device that makes use of the playback capabilities of ROM (read only) memory to reproduce carefully recorded and edited samples of individual instruments which make up the modern drum and percussion set.

Drum pad- Synthetic playing surface which produces electronic trigger signals in response to being hit with drum sticks. The playing surface buttons which are designed into a drum machine and played with the fingers. Drum-pad controller: Such a controller offers the performer a larger, more expressive playing surface that can be struck either with the fingers and hands, or with mallets and drum sticks for full expressiveness. Additionally, a drum controller will often offer extensive setup parameters.

Dry Signal- Signal which is bereft of any processing, such as eq, gating, reverb and the like. Opposite of "wet" signal. A signal that has had no effects added. When recording audio, this refers to an audio signal which has had no effects added. The best practice is to record dry so one can audition a variety of effects in post production.

DSP - Digital Signal Processing uses mathematics to operate on a digital signal (such as a digital audio stream) to generate some type of altered output. DSP is used heavily in software and hardware effects processing. DSP chips are found on an increasing number of sound cards to provide extra audio processing power and help relieve the computers CPU of this type of work, much like a 3D graphics accelerator would for rendering 3D graphics. Digital Signal Processing: DSP chips are found in sound cards, synthesizers, effects units, playback and speech synthesis, fax machines, modems, cellular phones, high-capacity hard disks and digital TVs. It is possible that the first DSP was used in the Speak & Spell game in the late 1970s from Texas Instruments. Typically, digital signal processing provides reverb or delay effects, loud speaker processing, EQ limiting and compression as well as feedback destroyers. Other audio uses are amplifiers that simulate concert halls and surround-sound effects for music and home theater. See DSP and Merge. DSP Hardware: DSP hardware frees up a computer’s processing power and speed for other tasks. TC Work’s Powercore is an excellent example of a PCI card which offers DSP processing on the hardware itself.

Dubbing- Adding further material to an existing recording. Also known as overdubbing. Within audio files, this refers to adding further material to an existing recording and is also known as overdubbing. See Overdubbing.

Ducking- A system for controlling the level of one audio signal with another. For example, background music can be made to 'duck' whenever there's a voice over. Ducking is used to automatically reduce signal levels when the level of a source signal exceeds a specified threshold. Often used for voice-over applications, the level of background music is automatically reduced (made to "duck"), allowing an announcer to be heard clearly.

Dynamic Microphone-A microphone which works through a diaphragm being attached to a coil, which operates within a strong magnetic field. The diaphragm vibrates in response to sound waves, which, in turn stimulates motion of the coil. The magnetic field causes an electric current to flow through the coil, with a voltage which varies in sympathy with the motion of the diaphragm. This measured change is the transduction of sound waves into an electrical signal. Not as good in terms of fidelity as a condenser type of microphone, but more sturdy and less prone to noise interference, hence it's wide use on stage, or where a certain kind of "grittiness" is required.

Dynamic Range- The difference in signal level between the loudest and quietest parts of a programme, expressed in decibels. Difference in signal level between the loudest and quietest parts of a performance / recording etc. It is measured in decibels. Incidentally, the dynamic range of the human ear is said to be @ 130 dB. The range of the softest to the loudest sound that can be produced by an instrument. Or the range of the low and high signal levels obtainable by a velocity sensitive keyboard. The greater the Dynamic Range, the more sensitive the keyboard. This refers to the difference between the loudest (maximum output level) and quietest (residual noise floor) sounds produced in an audio system without distortion or clipping. The dynamic range in a digital system is determined by the data resolution, about 6 dB per digital bit. In speech, the range rarely exceeds 40 dB; in music, it is the highest in orchestral works where a broad number of instruments are used, where the range may be as much as 75 dB.

Dynamics Processing- Processing which alters aspects of the dynamics (difference in sound level) of an audio signal.

Dynamics- The relative loudness or softness of a piece of music. Way of describing the relative levels within a piece of music.


Early reflections- The first sound reflections from walls, floors and ceilings following a sound created in an acoustically reflective environment.

Edit- To change the characteristics of something.

Enable-Disable- Antonyms, meaning to turn on or turn off. Synthesizers and sequencers have many controls requiring such action (like MIDI THRU).

Enhancer- A device designed to brighten audio material using techniques such as dynamic equalization, phase shifting and harmonic generation.

Envelope- In audio recording software this refers to the way in which the level of a sound or signal varies over time, including alterations in a sound's amplitude, frequency and timbre. In MIDI, an instrument can be altered by manipulating the envelope which contains parameters such as attack, sustain, decay and release. (See ASDR). Using patch editing software the user is able to edit the envelope of a synthesized sound thereby allowing its customization.

Envelope Generator- A device or process in a synthesizer or other sound generator that creates a time varying signal used to control some aspect of the sound.

Equaliser- Device for selectively cutting or boosting selected parts of the audio spectrum; useful in shaping the vocal or instrument for the desired sound like cutting the high end off of a violin.

Event- In MIDI, a signal that is transmittted- like note on, note off, program change, control change etc

Exciter- A circuit designed to enhance the presence of an audio signal by synthesizing new high frequency harmonics to make it sound more clear, punchy, bright, or loud, without the use of ordinary EQ or gain.

Expansion and Expander- A form of Dynamics processing. When lower level signals are lowered (attenuated) and higher level signals are raised (boosted), this is expansion. A devise that achieves this through circuitry or software is called an expander. This is the opposite of compression. A devise designed to decrease the level of low level signals and increase the level of high level signals, thus increasing the dynamic range of the signal.


Fade in/out - a feature of most audio editing software that allows the user to apply a gradual amplitude increase or decrease over some segment of the sound. Gradually increment (fade in), or decrement (fade out) the level of a signal.

Fader - also known as a slider or attenuator, this control allows the user to perform a gradual change to the amplitude of a signal. Commonly found as a feature of MIDI software programs. Sliding potentiometer which may increase or attenuate (the fade bit!) the gain of a signal. Usually associated with a mixing desk.

Fairlight –An early computer based music/ sampling workstation, developed in Australia through the mid/ late seventies by Peter Vogel and Kim Ryrie. Released in 1979 as the "Fairlight Computer Musical Instrument", it's most notable early users being Peter Gabriel and Stevie Wonder. Along with the American Synclavier. It went on to have a very significant impact on the music of the 1980's.

Fast Fourier Transform (FFT)- A computer algorithm which derives the fourier spectrum from a sound file.

Feedback - When the sound being produced by the output signal (from a loudspeaker) is picked up by the input (in a kind of circular loop). When feedback reaches a certain level it causes an exponential rise in the level of certain frequencies, such as the screaming howl familar to guitarists and microphone users, or in the case of lower frequencies, a kind of ever increasing rumble.

Filter- A electronic device that permits certain frequencies to pass while stopping others. Read our guide  to using filters here.

FireWire- A cross-platform implementation of the high-speed serial data bus, that can move large amounts of data between computers and peripheral devices. It features simplified cabling, hot swapping, and transfer speeds of up to 400-800 megabits per second.

Flange- an effect applied to a sound wherein a delayed version of the sound is mixed with the original. An effect created by layering two identical sounds with a slight delay (1- 20 mS) and slightly modulating the delay of one or both of the sounds. The term comes from the early days of tape recording when delay effects were created by grabbing the flanges of the tape reels to change the tape speed.

Flat (frequency) Response- When an amplifier / microphone / loudspeaker displays an even frequency response (an even efficiency of frequencies within its bandwidth). This is usually defined as being within 2 dB.

Flutter echo- Resonant echo that occurs when sound reflects back and forth between two parallel, reflective surfaces.

FM Synthesizers- These produce sounds by generating a pure sine wave (carrier) and then mixing it with a second waveform (modulator). When the two waveforms are close in frequency, a complex waveform is produced. By controlling both the carrier and the modulator it is possible to create different timbres, or instruments. FM synthesis is hardly used today being replaced by more realistic forms of synthesis, such as wave table synthesis.

Foldback- System for feeding one or more separate mixes to the performers for use while recording and overdubbing. Also known as a Cue mix.

Formant- Frequency component or resonance of an instrument or voice sound, that doesn't change with the pitch of the note being played or sung. For example, the body resonance of an acoustic guitar remains constant, regardless of the note being played.

Four Beat - A term used to describe music written in 4/4 timing ("Four-To-The-Floor").

Frequency- the rate per second at which an oscillating body vibrates. Usually measured in Hertz (Hz). The human ear can hear sounds whose frequencies are in the range 20 Hz to 20kHz. In audio, the number of repeating cycles of change in air pressure or oscillations in voltage that occur in one unit of time usually a second. Complex sounds are made up of many pure tones of different frequencies. For convenience, the human frequency range is divided into three rough areas or bands. High frequencies (between about 5 kHz and 20 kHz), Mid frequencies (between about 200 Hz and 5 kHz) and Low frequencies (between about 20 Hz and 200 Hz). Read our guide to EQ here.

Frequency Modulation- The encoding of a carrier wave by variation of its frequency in accordance with an input signal.

Frequency Response- A graph which shows how a system or piece of equipment or even an environment such as a room responds to different frequencies. Ideally, for audio work the graph should plot a flat line from below 20 Hz to above 20 kHz. In practise this is often not achieved, and the line will fluctuate up and down between these points, indicating that the equipment or environment makes some frequencies louder or quieter than others. Humans have a well documented "non-flat" response and this is the response used to specify the dB(A) scale for determining loudness. The term should not be confused with bandwidth which concerns itself only with the attenuation above an upper limit frequency and below a lower limit frequency and does not concern itself with the range between them. A measurement of the frequency range, that can be handled by a specific piece of electrical equipment or loudspeaker.

Full-Duplex- The ability to send and receive data simultaneously which, in digital audio terms, translates to being able to play and record audio at the same time. Many sequencing and multi-track recording programs use a sound card's full-duplex capabilities to allow recording to a new track while playing back previously recorded tracks for reference. Most modern sound cards are full-duplex, but many of the older ones are only able to record or play audio at different times. They are said to be "half-duplex".


Gain- An increase in strength or amplitude of a signal.

Gate- An electrical signal that is generated whenever a key is depressed on an electronic keyboard. This is used to trigger envelope generators and other events that need to be synchronised to key action. An electronic device designed to mute low level signals so as to improve noise performance during pauses in the wanted material.

General MIDI Mode- A convention specifying how a sequence (a song) should be constructed, so that it will play on a variety of hardware.

Glide – An effect where a note / pitch is decreased by a semitone, then "glides" its way back up to the original pitch.

Glitch- Describes an unwanted short term corruption of a signal, or the unexplained, short term malfunction of a piece of equipment. For example, an inexplicable click on a DAT tape would be termed a glitch. Also a free VST Plugin effect.

Global Editing- Affecting an entire file or program.

Graphic equaliser- An equaliser where by several narrow segments of the audio spectrum are controlled by individual cur/boost faders. The name comes about because the fader positions provide a graphic representation of the EQ curve. A device type that applies a series of band pass filters to a sound, each of which works on a certain range of the spectrum. The frequencies that fall within the range, typically one-third octave, can be boosted or cut. A type of equalizer that provides control over a fixed set of frequencies. Each filter provides linear cut/boost control over a fixed frequency. The number of filters on graphic equalizers range from three (low, mid, high) to well over eleven. While graphic equalizers generally have more filters than parametric equalizers, they are less flexible, in that the individual filter frequencies are not adjustable. Read our guide to EQ here.

Ground / Earth Loop- A condition which may occur in an electrical system where there is more than one Ground connection (see above), which causes a circulation, or looping of currents between ground points with cable resistance transforming this into fluctuations in voltage. Its symptom is a low hum @ 50 - 60 Hertz (see Frequency). If you are in the US it will be 60, in Europe 50.

GUI- Graphical user interface. A display that permits a user to select commands, menu items-by pointing at an icon (with a mouse) and clicking.


Hard disk recorder- A computer-based hardware and software package specifically intended for the recording, manipulation, and reproduction of the digital audio data that resides upon hard disk and/or within the computers own RAM.

Hardware: Computing devices and peripherals.

Hardware Sequencer- Sequencing can be performed by software programs or by hardware. Hardware sequencers also work with synthesizers, controllers, sound modules- creating and editing songs. A hardware sequencer is - as the name implies- hardware, containing a single-purpose program, one designed to provide sequencing.

Harmonic- (1) A special case of partial normally occurring in "musical" sounds, in which the frequency of the partial has a simple mathematical relationship to other partials. Generally they are all integer multiples of a particular fundamental frequency. (2) of or pertaining to musical harmony (the juxtaposition of one note with another or others).

Harmonic Distortion- When harmonics are present in an output signal which weren't a part of the input signal of an audio device, this is referred to as harmonic distortion. The addition of harmonics that were not present in the original signal. The presence of harmonics in the output signal of a device which were not present in the input signal.

Harmony - Harmonic concepts are the primary basis for the construction of music theory, e.g. "chords" and the concept of playing music in a "key" are built around the notion of having a fundamental note, with a series of notes higher in pitch than this, their pitches being in harmony with the fundamental note, in line with the harmonic principles mentioned above.

Headroom- The difference between the average operating power level of a circuit and the point at which distortion occurs.

Hertz (Hz)- base unit of frequency, commonly used multiples are kHz (kilohertz, 103 Hz), MHz (megahertz, 106 Hz), GHz (gigahertz, 109 Hz). One hertz simply means one cycle per second (typically that which is being counted is a complete cycle); 100 Hz means one hundred cycles per second, and so on. The unit may be applied to any periodic event, for example, a clock might be said to tick at 1 Hz, or a human heart might be said to beat at 1.2 Hz.

High pass filter- A device which allows higher frequency data to be transmitted, rejecting lower frequencies, as used in Graphic EQ’s. Read our guide to using filters here.

Hoover - term used for a sound of certain characteristics originally generated by Roland's Alpha Juno II synthesiser. Popularised by tracks such as Joey Beltram 'Mentasm' and Human Rescource 'Dominator'. You can find Hoover sound in our DMS old skool rave sample pack


I/O- The part of a system that handles inputs and outputs, usually in the digital domain.

ID3- small file that can be attached to an MP3 that contains album, artist, track, and other info.

Imaging- This is an audio listening term and refers to the ability of a speaker to position sounds precisely in space. A good stereo system can provide a stereo image that has width, depth and height. The best imaging systems will define a nearly holographic recreation of the original sound.

Interface- A MIDI "interface" connects the computer and MIDI instruments.

Insert Point- A connection which permits the insertion of an external signal processing device (reverb, compressor, gate, eq etc) into the signal path. A connector that allows an external processor to be patched into a signal path so that the signal now flows through the external processor.

Intermodulation Distortion-A form of distortion that introduces frequencies not present in the original signal. These are invariably based on the sum and difference products of the original frequencies.

International Standard Recording Code (ISRC)- The international identification system for sound and music video recordings. Each ISRC is a unique and permanent identifier for a specific recording and can be permanently encoded into a product. The encoded ISRC can also be used in automated data processing systems to identify the owners and other participants in sound and music video recordings. This associated metadata is essential for distribution of royalty payments.


Jack plug- A popular form of audio connector, available in stereo or mono formats.

Jitter- A form of digital distortion caused by a very slight imprecision of digital sampling times (when sound is recoded digitally, it is done by "slicing" the signal into many segments, see Sample for a further explanation), leading to amplitude (signal level) errors. The distortion is more pronounced at the higher end of the frequency spectrum.

Juno- line of synthesisers from Roland corporation, ranging from classic analogue synths such as Juno 60 and 106, and recently revived with Juno-D & G.


Kbps - "kilobytes per second", a measurement that is used to judge the size of an audio file. Uncompressed audio such as WAV format is 1411 kbps, MP3 compresses this size to about 1/10 on average (varies depending on user settings when encoding)

Keyboard Assignment- The assignment of specific sounds to an area of the keyboard. For example, the lowest octave could be drum sounds, the next octave could be an electric bass, the rest of the keyboard could have various piano samples assigned to it.

Keyboard split- a setup of a keyboard where different notes trigger different sounds. Also known as zoning.

Keygrouping - see Multisampling.


Layering- The ability to place or stack two or more sounds on the same area of the keyboard (or in a sequencer) to create a denser (thick) sound.

LAN- Local Area Network. Computers connected in one location.

LFO - a low frequency oscillator that is used to alter a sound's frequency or amplitude. Low Frequency Oscillator. An oscillator used for modulation whose range is below the audible range (20 Hz). Example: Varying pitch cyclically produces vibrato.

Librarian- In MIDI / Computer terminology, a software program designed to store synthesizer voice information.

Limiter- Signal processing which sharply cuts off output once it reaches a certain preset level. Roughly it is a form of compression (see dynamics processing) with a very high ratio (10/1 or over) used mostly for for the protection of ears loudspeakers etc.

Line level signal- For an audio device which uses unbalanced inputs / outputs, a line level signal is a signal with a level of -10dBV (0.316 volt). for a device which uses balanced inputs / outputs, it is a signal whose level is at +4dBm (1.23 volts). A nominal signal level which is around -10dBV for semi-pro equipment and +4dBu for professional equipment.

Linear - A device where the output is a direct multiple of the input.

Logic - Type of electronic circuitry used for processing binary signals comprising two discrete voltage levels. Also sequencing software made by Apple.

Loop - to repeat a sequencer pattern or portion of an audio sample repeatedly.

Low pass filter (LPF) - A filter which attenuates frequencies above its cutoff frequency. A filter which attenuates frequencies which are above it's stated cutoff frequency. Read our guide to using filters here.


Mapping- In sequencing it is the process of identifying patches and keys so that sound files can be played properly. A key map will translate values for MIDI messages so that the correct keys will be played whereas a patch map functions to identify the correct patches or sounds.

Marker- Something used to record a position. MIDI markers indentify, for example, musical cues. They work like tab stops in a word-processor.

Mapping- The process of identifying patches and keys, so that sound files can be played properly. A key map will translate values for MIDI messages, so that the correct keys will be played. A patch map functions to identify the correct patches (sounds, instruments).

Master - A device which controls another device, known as the slave. The final mix of a piece of music. “To master” a process of dynamics processing performed by a mastering engineer to improve and optimise a final recording for the end format (e.g. CD or Vinyl) and listener.

MIDI - Musical Instrument Digital Interface provides a standardized method for MIDI devices such as synthesizers, samplers, sound cards, etc. to communicate musical events and data to each other. See the MIDI Guide for a detailed explanation.MIDI Note Numbers- the numerical values (0-127) assigned to musical notes in the MIDI system. A standard MIDI file contains

MIDI File (SMF) Format- MIDI messages (along with timing information) can be collected and stored in a computer file system, in what is commonly called a MIDI file, or more formally, a Standard MIDI File (SMF). The SMF specification was developed by, and is maintained by, the MIDI Manufacturers Association (MMA). MIDI files are typically created using computer-based sequencing software (or sometimes a hardware-based MIDI instrument or workstation) that organizes MIDI messages into one or more parallel "tracks" for independent recording and editing. In most sequencers, each track is assigned to a specific MIDI channel and/or a specific General MIDI instrument patch. Although most current MIDI sequencer software uses proprietary "session file" formats rather than SMF, almost all sequencers provide export or "Save As..." support for the SMF format. An SMF consists of one header chunk and one or more track chunks. There exist three different SMF formats; the format of a given SMF is specified in its file header. A Format 0 file contains a single track and represents a single song performance. Format 1 may contain any number of tracks, enabling preservation of the sequencer track structure, and also represents a single song performance. Format 2 may have any number of tracks, each representing a separate song performance. Sequencers do not commonly support Format 2. Large collections of SMFs can be found on the web, most commonly with the extension .mid. These files are most frequently authored with the assumption that they will be played on General MIDI players. See our selection of MIDI file packs here.

MIDI bank change- A type of controller message used to select alternate banks of MIDI Programs where access to more than 128 programs is required.

MIDI Cable- A special wire used to carry MIDI data; it has three shielded conductors connected to five-pin DIN plugs at both ends.

MIDI CLOCK - a system real time message that enables the synchronization of different MIDI devices. The standard rate is 24 divisions per beat. Allows instruments interconnected via MIDI to be synchronized. The MIDI Clock runs at a rate of 24 pulses-per-quarter- note.

MIDI Continuous Controller- Allows continuously changing information such as pitch wheel or breath controller information to be passed over the MIDI line.

Midi control change- Also known as MIDI Controllers or Controller Data, these messages convey positional information relating to performance controls such as wheels, pedals, switches and other devices. This information can be used to control functions such as vibrato depth, brightness, portamento, effects levels, and many other parameters. A term used to describe the physical interface by means of which the musician plays the MIDI synthesizer or other sound generator. Examples of controllers are keyboards, drum pads, wind synths and so on. Other forms of controllers include drum, guitar, or wind controller. Real-time controllers are either continuous controllers (wheels, joysticks, sliders, foot pedals, breath controllers) or switch controllers (footswitches or other on-off devices). Many MIDI controllers do not have sounds but are used specifically to send MIDI data to another device such as a computer or a sound module.

MIDI Sequencer- A piece of digital hardware/software that can instruct a compatible instrument to switch notes on/off at whatever velocity they were "recorded" at. Rather than recording sound or "audio" however it records the parameters of the note. The sounds triggered are dependent on the MIDI instrument or sampler supplying the sound. There are up to 16 channels per MIDI loop operating within increments of 0 - 127. M.I.D.I. instructions (e.g. turn note off, velocity etc), are known as "events".

Mixer- A device for combining, controlling and routing audio signals.

Modular Synthesiser- A synthesiser where the individual sound generators or processors such as oscillators, filters, amplifiers, envelope generators etc. are physically separate units which can, or have to be, connected together by the user. This is usually achieved by simply plugging a cable from one unit's output to an input on another or the same unit, using a patchcord. The earliest synthesisers where of this type and this is the origin of the usage "patch" to describe the parameter settings on modern synthesisers which no longer use this arrangement. Systems of this type where made by Moog (series III), Roland (System 100 and 700) and Korg (MS10, 20 etc.). These systems were very flexible and led naturally to creative experimentation, but were expensive to manufacture and market. The arrival of software synthesisers has seen revived interest in modular synthesisers, with synths like Arturia's Moog Modular.

Modulation - the fast oscillation of one or more operators or sound waves of a synthesized sound. Commonly used in FM synthesis to add some complexity and texture to a sound. Many MIDI controllers and keyboards provide a specific wheel or slider for controlling the modulation of an instrument sound (often referred to as the mod-wheel). The process of one audio or control voltage source influencing a sound processor or other control voltage source. Example: Slowly modulating pitch cyclically produces vibrato. Modulating a filter cyclically produces wah-wah effects.

Monitor - A reference loudspeaker used for mixing. The action of listening to a mix or a specific audio signal.

Monophonic - only one note of an instrument may be played at a time.

Monotimbral - only one instrument sound (timbre) may be played at a time.

Motherboard- The main circuit board within a computer into which all the other components plug or connect.

MP3 (.mp3) - MPEG Layer III, digital audio compression format achieving smaller file sizes by eliminating sounds the human ear can't hear or doesn't easily pick up.

MPU-401 Compatible- The reference is to a standard interface. (It derives from Roland's initial design.) Importance: MS DOS MIDI software often supports this user base, but not always.

Multisample - The creation of several samples, each covering a limited musical range, the idea being to produce a more natural range of sounds across the range of the instrument being sampled. For example, a piano may need to be sampled every two or three semitones in order to sound convincing. This is known as "Key grouping".

Multi-timbral - Capable of producing more than one type of tone-color or instrument sound at the same time.

Mute- A sequencer command to turn off the specified track(s).


Natural Frequency - The frequency of vibration or oscillation which a system (anything from a road bridge to an violin string) will inherently adopt according to its structure given a suitable excitation, such as a gale force wind or a bow. Also called the normal mode.

Near Field / Close Field - The area which is close to the source. If we take a mic and place it right up against a sound source, we will be picking up it's sounds as they are in the near field, and if we take the microphone and place it far away from the sound source, we would be picking up the sounds (so long as it isn't too far away!) as they are in the WIDE field. Most commonly used to describe small loudspeakers which are designed to sound at their best a metre or two away from the listeners ear, hence lessening (but not eliminating the effects) of sound radiation in an acoustically imperfect room. Near field- Some people prefer the term 'close field', to describe a loudspeaker system designed to be used close to the listener. The advantage is that the listener hears more of the direct sound from the speakers and less of the reflected sound from the room.

Noise - A word used to describe signals which humans consider to contain little useful information, or which they actually find unpleasant.

Noise Floor - Amount of background noise produced by a piece of audio hardware, measured in dB's.

Noise Gating -cutting the signal for very short periods of time when it falls below a certain level - useful as a form of noise reduction and occasionally as an effect in itself.

Noise reduction - System for reducing the level of ambient noise or hiss present in a recording. Read our guide to basic audio editing here.

Noise shaping- A system for creating digital dither such that any added noise is shifted into those parts of the audio spectrum where the human ear is least sensitive. An audio tool for creating digital dither allowing added noise to be shifted into those parts of the audio spectrum where the human ear is least sensitive. See Dithering.

Non Linear Recording / Editing - An advantage of the way digital data is stored / retrieved (as separate "bits" of information, is that these bits of information can (in theory) be accessed and manipulated in any order (Random Access). In terms of digital audio and video this means that recorded material may be accessed and edited easily in a random, or non linear way, without physical manipulation of a medium such as tape (rewinding, splicing etc).

Normalise - To boost the amplitude of a digital sound so that it is as high as it can be without clipping (0 dB). This is done by taking the highest level, then adjusting the rest of the signal accordingly. A socket is said to be normalised when it is wired such that the original signal path is maintained unless a plug is inserted into the socket. The most common examples of normalised connectors are the insert points on a mixing console. Read our guide to basic audio editing here.

Notation Software - A computer program, capable of displaying and printing MIDI information as standard musical notation. Although sequencers can include notation capability, they lack the sophistication of true notation programs which often have scanning capabilities allowing quick input of music for transposing to another key.

Nyquist frequency - The highest frequency that any given digital audio system can capture. Defined as one half the sampling rate of that system. The highest frequency that can be reproduced accurately when a signal is digitally encoded at a given sample rate. The theory being, Nyquist frequency is half of the sampling rate. As in, when a digital recording uses a sampling rate of 44.1kHz, the Nyquist frequency is 22.050kHz. If a signal being sampled contains frequency components that are above the Nyquist limit, aliasing will be introduced in the digital representation of the signal unless those frequencies are filtered out prior to digital encoding.


Octave - a frequency ratio of 2:1. A musical distance (interval) of 12 semitones. Measure of the distance between one note and another note of the same name, which is eight full notes above or below it on the musical scale. An example of an octave would be "C, D, E, F, G, A, B, C". Another way of looking at it would be to say that a note which is an octave higher on the musical scale will also have a frequency which is twice as high e.g. if A4 has a frequency of 440 Hz, then A5 (an octave above) will have a frequency of 880 Hz.

Off-line - A process carried out while a recording is not playing. For example, some computer-based processes have to be carried out off-line as the computer isn't fast enough to carry out the process in real time. This may also allow processes such as audio rendering to be carried out faster than real time.

OGG Vorbis – An open source audio codec designed to compete with MP3. Since it is not licensed like MP3, software using this codec does not have to pay royalties.

Ohm / "Ohm's Law": - Ohm's Law is one of the fundamental laws of electronics, and pertains to the relationship between current and voltage / resistance in an electrical conductor. This relationship states that "Current = Voltage / Resistance". The usual way of expressing this in mathematical terms is "I = V/R", or to make things confusing, you could also say that "V = I / R", or R = V / I. The current is measured in "amperes" or "amps" the voltage is measured in "volts" and finally, the resistance is measured in OHM's. So as we can see from above, an "Ohm" is a measurement of the resistance in an electrical conductor. Which can be calculated using the R = V / I equation above. Hence, when someone says that their speakers have an "Impedance" of 8 Ohms, the "impedance" is referring to the factor by which the electrical signal is impeded, hence, a 4 Ohm speaker will offer half the resistance to the electrical current flowing through it than an 8 Ohm one. Having said this impedance varies greatly, and impedance ratings are usually just an average.

Omni- Meaning all, refers to a microphone that is equally sensitive in all directions, or to the MIDI mode where data on all channels is recognised.

Omni directional - Will pick up sound from all angles equally. An omni directional polar pattern should adhere very closely to that of a circle / sphere. There are also Half – Omni directional (hemispherical) microphones which do the same thing, only over 180 degrees rather than 360. "PZM" (Pressure Zone Mic) microphones are an example of this. For microphones is means receiving sound evenly from all directions. For speakers this means an even coverage in all directions.

One-Shot Sample - Digital samples that aren't looped. Examples of a "one-shot sample" would include drum sounds (kick, snare, toms and so forth), orchestra hits.

Operating system- The basic software that enables a computer to load and run other programs.

Oscillator - a synthesis module used to create a cyclical waveform. These simple waveforms may then be passed through other modules (LFOs, envelopes, etc.) to add some character. An electronic device capable of generating a recurring waveform, or a digital process used by a synthesizer to generate the same.

Overdub - The ability to record one sound on top of another. Adding something to a previous recording, so that the two (or more) parts may be subsequently played together as a synchronous whole. A part of Multi track Recording. Enables one or more of previously recorded tracks to be monitored while simultaneously recording one or more signals onto other tracks. This process can be repeated until the song or soundtrack has been built up. If a mistake is made, it is possible to rescue the tape to the desired starting point and repeat the process until you have the best take on tape.

Overload- Distortion which is caused by exceeding the dynamic range of a circuit. To exceed the operating capacity of an electronic or electrical circuit.

Oversampling- A digital filtering technique used in CD components where extra data points are added to the audio read from a disc, creating a signal that is some multiple (usually two, four, or eight times) of the CD format's standard sampling frequency. This process raises the frequency of any false information, which can then be removed by an analog filter. Using the high sample rate, the digital data may be processed with a very steep slope digital filter. As the filter is in the digital domain, unpleasant side-effects such as phase effects are eliminated.


Pan- To pan is to move the sound between full left and full right in a stereo sound field. It resembles the "balance" function of a HI-FI Amplifier.

Parallel - A means of connecting two or more circuits together so that their inputs are connected together, and their outputs are all connected together.

Parameters- Conditions, guidelines or settings.

Parametric EQ- An equaliser with separate controls for frequency, bandwidth and cut/boost. A type of equalizer that provides control over each filter's frequency and the amount of cut or boost of each filter. Typically, parametric equalizer's provide three to four filters that work in parallel, each one filtering a different frequency of the spectrum (i.e. low, mid, high). While parametric equalizers generally have fewer filters than a graphic equalizer, they are more flexible and provide finer control, due to the adjustability of the filtered frequencies.

Passive - A circuit with no active elements.

Passive Crossover - Most domestic "Hi Fi's" of lower power use what is known as a "Passive" crossover system, where the frequencies are split after the signal has been amplified.

Patch - In a synthesiser the patch settings will determine the nature of the sound it produces. Often now referred to as a preset.

Pattern Recording - Building up a pattern using a sequencer, e.g. a synth line, then embellishing it.

Peak - The maximum instantaneous level of a signal. The highest point in the audio waveform on a graph of a sound wave that would look something like a mountain peak. It is the point of greatest voltage or sound pressure in a cycle.

PCM- Pulse code modulation, a process of digital recording.

PFL - Pre Fade Listen; a system used within a mixing console to allow the operator to listen in on a selected signal, regardless of the position of the fader controlling that signal.

Phantom Power - A special +48V DC power supply for the use of Condenser type microphones. It is known as "phantom" power as the power travels through the same cable as the audio signal.

Phase - the relative position of a wave to some reference point. Phase describes the time relationship between two different waveforms. It is expressed in degrees, with 360 degrees representing a full cycle. It is the amount by which one sine wave leads or lags a second wave of the same frequency. The difference is described by the term phase angle. Sine waves in phase reinforce each other; those out of phase cancel.

Phaser- An effect which combines a signal with a phase shifted version of itself to produce creative filtering effects. The rate of most phasers are controlled by means of an LFO.

Pitch - A continuous frequency over time.

Pitchbend - A synthesiser performance technique that involves sliding the pitch of a sound up or down by means of a controller.

Pitch shifter - Device for changing the pitch of an audio signal without changing it's duration.

Pitch to MIDI Conversion - Many programs have this feature whereby an audio signal is converted to MIDI data. This is especially useful in notation programs where the data can then be customized and printed. The audio signal needs to be monophonic, thereby having only one voice at a time.

Plug-In - a "client program" that is used to expand the functionality of a "host program", such as a sequencer or digital audio editor. The host provides the plug-in with some type of input data such as digital audio samples, which is then processed to generate new output, such as effected digital audio. A plug-in is often run seamlessly from within a host program appearing to be part of the standard interface. One plug-in can be used by multiple host programs that share the same plug-in format. Two popular plug-in formats used in computer music and audio are DirectX and VST digital audio plug-ins. A software based application that is accessed via a recording and editing application such as Cubase or Pro Tools.

Polyphonic - more than one note of an instrument sound may be played at the same time. Hardware and software synthesizers usually range from 1 to 128 notes polyphony. The number specifies exactly how many notes may be played at once before cutting-off previously played notes. An instrument that can play only one is said to be Monophonic. the ability to play many different notes at once.

Polyphony- Derivative from the Greek term meaning variety of tones, it is the number of notes which can be played simultaneously. Any synthesizer has a maximum polyphony which cannot be exceeded. If the polyphony is exceeded, MIDI data will drop out from MIDI channels used near the end of the sequence. The ability of an instrument to play two or more notes simultaneously. An instrument which can only play one note at a time is described as monophonic.

Portamento - A gliding effect that allows a sound to change pitch at a gradual rate, rather than abruptly, when a new key is pressed or MIDI note sent. A musical term referring to the gliding effect that allows a sound to change pitch at a gradual rate, rather than abruptly.

Post Production - Work done to a stereo recording after mixing is complete.

Post-fade - Aux signal taken from after the channel fader so that the aux send level follows any channel fader changes. Normally used for feeding effects devices.

PPQN- Pulses Per Quarter Note.

Preamplifier - This is usually referred to as preamp and is a device that takes a source signal, such as from a turntable, tape deck or CD player, and passes this signal at line level on to a power-amplifier. The preamplifier may have a number of controls such as source selector switches, balance, volume and possibly tone controls. This is typically the largest gain stage in a sound set-up.

Preset - A pre-programmed sound and control setup on a sampler or synthesizer. Presets can be made up in advance of a performance, stored in memory, then recalled instantly when desired. Our Hardstyle Manipulation sample pack features patches for Cakewalk's Z2TA+ synthesiser.

Pulse Wave - Similar to a square wave but non-symmetrical, pulse waves sound brighter and thinner than square waves, making them useful in the synthesis of reed instruments. The timbre changes according to the mark/space ratio of the waveform.


Q - A measure of the resonant properties of a filter. The higher the Q, the more resonant the filter and the narrower the range of frequencies that are allowed to pass.

Quantisation- To quantise is to force all notes played to fall on the nearest beat specified.


RA (.ra) - "Real Audio" compressed file type from Real Networks.

RAM- Random Access Memory. Memory used when manipulating data using software.

Real Time - An audio process that can be carried out as the signal is being recorded or played back. The opposite is off-line, where the signal is processed in non-real time. In sequencing software there are generally two types of recording procedures, real-time; and step-time. Real-time is literally recorded in time that has not been adjusted, such as slowed down. Step-time is a recording method of inputting MIDI data that is sequentially laid down note-by-note, chord-by-chord and is particularly helpful for inputting data at one’s own pace.

Refill - an soundset expansion pack for Propellerheads Reason. You can find Refills in our Synth Patch section.

Release - the final period of an envelope during which a sound's attribute (such as volume) decreases from the sustain level to 0 (silence). The release period is usually started upon releasing a keyboard's note. This period of the envelope defines how a sound finishes off. A long release time causes a sound's attribute to fade away slowly, while a short release time causes it to drop out quickly. The rate at which a signal amplitude decays once a key has been released. The time taken for a level or gain to return to normal. Often used to describe the rate at which a synthesized sound reduces in level after a key has been released. The rate at which a synthesized sound reduces in level after a key has been released.

Resample - to recalculate samples in a sound file at a different rate than the file was originally recorded. If a sample is resampled at a lower rate, sample values are removed from the sound file, decreasing its size, but also decreasing its available frequency range and possibly introducing aliasing. Resampling to a higher sample rate, often interpolates extra sample values into the sound file. This increases the size of the sound file but may not increase the quality (depends on the algorithm used).

Resolution - The accuracy with which an analogue signal is represented by a digitising system. The more bits are used, the more accurately the amplitude of each sample can be measured, but there are other elements of converter design that also affect accuracy. High conversion accuracy is known as high resolution.

Resonance - A frequency at which a material object will vibrate. In a filter with resonance, a signal will be accentuated at the cutoff frequency. The characteristic of a filter that allows it to selectively pass a narrow range of frequencies. Read our guide to using filters here.

Resonant Frequency - Any system has a resonance at some particular frequency and at that frequency, even a slight amount of energy can cause the system to vibrate. A stretched piano string, when plucked, will vibrate for a while at a certain fundamental frequency. Plucked again, it will again vibrate at that same frequency. This is its natural or resonant frequency. While this is the basis of musical instruments, it is usually undesirable in music-reproducing instruments like audio equipment or room acoustics.

Reverb - an effect that simulates natural reverberations (sound reflections) that occur in different rooms and environments to create an ambience or sense of spaciousness. Acoustic ambience created by multiple reflections in a confined space. Acoustic ambience created by multiple reflections in a confined space. Also, a type of digital signal processing that produces a continuous wash of echoing sound, simulating an acoustic space such as a concert hall. Reverberation contains the some frequency components as the sound being processed, but no discrete echoes.

Ring modulator - A device that accepts and processes two input signals in a particular way. The output signal does not contain any of the original input signal but instead comprises new frequencies based on the sum and difference of the input signals' frequency components. Ring Modulators will be covered in depth later in the series. The best known application of Ring Modulation is the creation of Dalek voices but it may also be used to create dramatic instrumental textures. Depending on the relationships between the input signals, the results may either be musical or extremely dissonant - for example, ring modulation can be used to create bell-like tones. (The term 'Ring' is used because the original circuit which produced the effect used a ring of diodes.)

Rip - to extract or copy data from one format to another more useful format. The most common example is found in the phrase "CD Ripping" which means to copy audio tracks from an ordinary audio CD and save them to hard disk as a WAV, MP3 or other audio file.

RMS - Acronym of Root Mean Square, it is a measure of the average level of a signal (by squaring then averaging the voltages produced by a signal). "RMS Continuous" is usually the most conservative (and the best) way of estimating the power output of an amplifier, or the power handling of loudspeakers, and the most common way of defining AC voltage. A method of specifying the behaviour of a piece of electrical equipment under continuous sine wave testing conditions.

Roll-Off - Rate of attenuation of a signal (usually by a filter), measured in Decibels per Volt (DbV) The rate at which a filter attenuates a signal once it has passed the filter cut-off point.

ROM- Read Only Memory. Information stored permanently in a computing device.


Sample - a sound or short piece of audio stored digitally in a computer, synthesizer or sampler. The word sample may refer to either a single moment in a digital audio stream (the smallest piece of data used to represent an audio signal at a given time) or a complete sound or digital audio stream made up of a collection of individual samples. See our guide to basic audio editing.

Sampler - a hardware device or software application that uses samples as it's main method of generating it's audio output. Samplers often use a number of samples together to create realistic sounding reproductions of real sounds and musical instruments. For more details on this technique, see Wavetable Synthesis. Also called a digital sampler. A type of synthesizer which derives it's sounds from recording actual sounds (instruments or non musical sounds) and then storing them in computer memory, either floppy discs, hard drive, or recorded onto CD-ROM. They are used extensively for generating sound effects. See our wav sample pack selection here.

Sample and hold - Usually refers to a feature whereby random values are generated at regular intervals and then used to control another function such as pitch or filter frequency. Sample and hold circuits were also used in old analogue synthesizers to 'remember' the note being played after a key had been released.

Sample Rate - the resolution of digital audio that determines it's sound quality. When audio is digitally recorded (digitized), it must be converted into a series of samples which can be stored in memory or on disk. The sample rate defines how many samples are recorded per second of audio input and is measured in Hz (Hertz, cycles per second) and kHz (Kilohertz, thousand cycles per second). Click the examples below to hear the difference between a few commonly used sample rates. The rate at which samples of a waveform are made. Must be twice the highest frequency one wishes to capture. Commercial compact discs use a rate of 44,100 samples per second. is the rate at which samples of a waveform are made and must be twice the highest frequency one wishes to capture. Commercial compact discs use a rate of 44,100 samples per second. When audio is digitized, the sampling rate is the number of "pictures taken" in a second. A high sample rate means that the resolution of the recording is high, thus very "accurate". Most common sample rates in professional recording are 44.1Khz and 48Khz.

Sawtooth Wave - So named as the shape of this wave (when pictured through an oscilloscope) resembles that of the jagged teeth of a saw. It differs from the Square wave described above in that it contains both even and odd harmonics (giving it a strident, somewhat aggressive quality).

SCSI Port- The port on the back of the instrument to which SCSI devices are connected. SCSI: Abbreviation for Small Computer Systems Interface. An interfacing system for using hard drives, scanners, CD-ROM drives and similar peripherals with a computer. Each SCSI device has its own ID number and no two SCSI devices in the same chain must be set to the same number. The last SCSI device in the chain should be terminated, either via an internal terminator, where provided or via a plug-in terminator fitted to a free SCSI socket.

Sequencer - a hardware device, software application or module used to arrange (ie. sequence) timed events into some order. In digital audio and music, sequencers are used to record and arrange MIDI and/or audio events into patterns and musical compositions.

Sibelius - Brand name for the most well known form of music notation software (software which transposes what is played into a musical score).

Signal Processor - An electronic device which audio signals can be routed through to affect the sound of that signal. Examples: delay and reverb units, distortion devices, etc.

Signal to Noise ratio (S/N) - At it's most basic, this is the difference between the level of background noise (noise floor), and the level of signal, measured in dB's.

Sine wave - the most basic waveform, consisting of a single partial. Forms the basis of all complex, periodic sounds. Sine Wave A geometrical waveform having a curve defined by the function y= sin x. In theory there are no other partials present and it can therefore be considered as the basic component from which (by combination) all other waveforms are made. It is the basic building block of all sound. Sometimes used quite incorrectly to describe pure tones irrespective of waveform.

SMPTE - Society of Motion Picture and Television Engineers. Often used to mean SMPTE Time Code- a time based synchronization code.

Software- Instructions that enable a computing device to carry out its functions.

Solo- If you want to listen exclusively to one track, you can mute all other tracks. Alternative: Select a track to "solo" (a feature that some sequencing programs offer). [See also: MUTE.]

Song Position Pointer- MIDI timing information that enables MIDI sequencers to lock to an encoded analog tape track that has this location information recorded.

Sound Card - a hardware interface that is either built into a computer's motherboard or inserted into one of the computer's internal expansion slots. Sound cards allow the computer to play digital audio and/or musical instrument sounds. Many sound cards also provide a MIDI interface.

Sound Fonts (.sf2) are an easy way to load multi sampled sounds into your VST sampler or synth. Compatible samplers include: Halion, NN-XT, Kontakt, ESX24 and many commercial and freeware VST instruments. See the Wikipedia Sound Font entry for more detailed information.


Sound module- A sound making device that does not have an integral controller and must be controlled remotely.

Sound On Sound - An Early recording technique to allow pseudo-multitracking.

Square Wave - A geometrical waveform typically generated by an oscillator.

Standard MIDI File - Identified by its extension (.MID, sometimes .MFF or .SMF), this is a file that can store MIDI messages, such as songs. The data in a MIDI file can be played, manipulated, edited. A MIDI file comprises actions performed on an instrument (keys pressed, how hard...) There is a standard MIDI file format. A principal advantage of a MIDI file: It uses comparitively little disk space, but more importantly, it is a standard across platforms and sequencers. See our selection of dance midi files here.

Step-time- In sequencing this refers to entering notes one at a time.

Subtractive Synthesis - The synthesis of a new sound by the refinement through filters etc of a harmonically complex waveform. The process of constructing a sound by starting with a complex sound and then removing harmonics with a filter. A low pass filter is most commonly used. The cutoff frequency of the filter is usually dynamically varied, which changes the harmonics that are removed.

Sustain - The period of an envelope during which a sound's attribute (such as volume) holds at a constant level. The sustain period starts at the end of the decay period and holds until the release period is started (usually by a keyboard note release). Unlike the other periods of an envelope, the sustain period does not have a slope because it must be capable of holding indefinitely (as long as a keyboard note is pressed). Part of the ADSR envelope which determines the level to which the sound will settle if a key is held down. Once the key is released, the sound decays at a rate set by the Release parameter. Also refers to a guitar's ability to hold notes which decay very slowly.

Sweet Spot - The optimum position for a listener within the sound field created by a pair of stereo speakers, or the optimum position for a microphone relative to it's pickup pattern and the sound field created by whatever is being recorded. The optimum position for a microphone, or for a listener relative to monitor loudspeakers.

Sync - A system for making two or more pieces of equipment run in synchronism with each other.

Synclavier - A digital synthesiser/ music workstation developed by Sydney Alonso (hardware) and Cameron Jones (software) at Dartmouth College, New Hampshire, United States. The first prototype was released in 1975. Like the Fairlight mentioned above, the Synclavier made a great impact on the increasingly digitally based music of the 1980's.

Syncopate - to shift the regular accent of a tone or beat by beginning on an unaccented beat and continuing through the next accented beat.

Synthesiser- A programmable musical instrument capable of producing sound.

Sysex - System Exclusive Messages or Sysex messages do exactly what is implied - they send commands specific to a particular device in a MIDI setup where global control of all settings is not desired. They are particularly useful if your MIDI modules or keyboards are in a chain and isolated commands are necessary.


Tempo - The rate of speed at which a musical composition proceeds. Usually uses a quarter note as the timing reference. The rate of the 'beat' of a piece of music measured in beats per minute.

Test tone- A steady, fixed level tone recorded onto a multi track or stereo recording to act as a reference when matching levels.

Timbre - The characteristics that differentiate one instrument, voice or sound from another. It can be thought of as the texture or characteristics that define a sound. Notes of the same pitch and volume may have a different timbre. In electronic music, timbre sometimes refers to a synthesiser voice or patch (see Multitimbral). the property of a sound that distinguishes it from all other. Tone color. The quality of a sound determined by its partial structure, that is the relative frequencies and amplitudes of the various sine waves which collectively make up that particular sound. It is more or less synonymous with "tone". It is this quality which allows you to distinguish between two different instruments playing the same pitch at the same volume.

Time Variant Amplifier - Alters the volume of an audio signal over a period of time, often based on an envelope.

Time Variant Pitch - Alters the pitch of an audio signal over a period of time, often based on an envelope.

Tone Generator - essentially a synthesiser without a keyboard.

Track - In audio software, tracks generally contain one audio layer or audio file; there is multi-track software or stereo (2 track) audio software. With MIDI sequencing, tracks are nothing more than an organizing tool commonly confused with MIDI Channels which are necessary for delineating different instruments. Although only one MIDI channel can be used at a time, many tracks can be assigned to this same MIDI channel. This is particularly useful when parts come in or fade out as these tracks can then be easily muted or soloed. Most sequencers allow an unlimited number of tracks within each song. Sequencers borrowed this term from multi-track recording studios, referring to tape tracks. A track is one of a number of locations where a musical part can be recorded and played back.

Tracking - The system whereby one device follows another. Tracking is often discussed in the context of MIDI guitar synthesizers or controllers where the MIDI output attempts to track the pitch of the guitar strings. Or the layering of recordings, usually vocals to “thicken” the over all sound.

Track name- Names like "melody line," "bass line," "left hand," etc. are assigned to tracks to help determine the instrumentation of a sequence.

Transpose - This allows a musical composition to be played in a different key. Both synthesizers and sequencers can carry out this function. To shift a musical signal by a fixed number of semitones.

Tremolo - A rapid alternation of two tones. Usually a third apart. On a synthesizer, this effect can usually be controlled by the modulation wheel or modulation amount. A cyclic change in amplitude, usually in the range of 7 to 14 Hz. Usually achieved by routing a LFO (low frequency oscillator) to a VCA (voltage controlled amplifier).

Triangle Wave - A geometrical waveform typically generated by an oscillator. It is triangular in shape and comprises the same sequence of only odd numbered (1, 3, 5, 7, etc.) harmonic partials as the square wave, but as the amplitude of each harmonic is the reciprocal of the square of the harmonic number (i.e. the 3rd. harmonic is a 9th. the amplitude of the 1st.), the sound is much weaker or more mellow. See also Pulse Wave, Ramp Wave, Sine Wave, Square Wave.

Trim - Controls the level of input on a mixing desk or plugin.

Tuning - 440 Hertz is the normal Western tuning value however, this can be easily be adjusted in a synthesizer to suit the type of music being performed. The pitch can be altered by raising or lowering the value as plus or minus cents. Playing non-Western music may dictate the need to adjust the tuning of a synth.

Tweeter - This is the smaller speaker within a speaker cabinet used to reproduce the higher range of frequencies. To form a full-range system, a tweeter needs to be combined with a woofer, (2-way system), or a woofer and midrange, (3-way system).


Unbalanced- A 2-wire electrical signal connection where the inner or hot or +ve (positive) conductor is usually surrounded by the cold or -ve (negative) conductor, which forms a screen against electrical interference.

Unidirectional - A microphone response / pickup pattern which is very sensitive to sounds which are produced in front of the microphone, but very Insensitive to sounds which are produced behind the microphone. (see also Polar Pattern)

Unison - To play the same melody using two or more different instruments or voices.

USB: (Universal Serial Bus) is a "plug-and-play" interface between a computer and add-on devices such as audio devices, joysticks, keyboards, scanners, and printers. With USB, a new device can be added to your computer without having to add an adapter card or even having to reboot your computer.


Valve - Vacuum tube amplification component, also known as a tube.

Variable bit rate (VBR) – An encoding process where the codec makes the choice for how many bits are used on each segment of music. More complex segments get more bits. VBR was created with the goal of efficient use of file sizes.

VCA (Voltage Controlled Amplifier) - A device which responds to a control input voltage (usually @ 0-5 Volts DC). As the input voltage increases, so the level of signal decreases by a proportionate amount.

VCF (Voltage Controlled Filter) - Works along the same principles as a VCA (see above), only with a VCF, it is the roll off frequency of a filter which is affected by changes in control input voltage. A filter whose cutoff frequency or resonant frequency is determined by a control voltage.

VCO - see Voltage-Controlled Oscillator. Oscillator whose output frequency is controlled by variations in Voltage.

Velocity- Velocity is the MIDI way of determining how hard a note is pressed on the keyboard controller.

Vibrato - A cyclic change in pitch, usually in the range of 7 to 14 Hz. Pitch modulation using an LFO to modulate a VCO.

Vocoder - An audio effect that produces "robotic" sounding results when processing vocal input. It uses an algorithm called ring modulation to produce the effect. Examples can be found in some disco and modern music, such as the Beastie Boys' "Intergalactic". A digital signal processor that applies a filter on a sound based on the frequency characteristics of a second sound. By taking the spectral content of a human voice and imposing it on a musical instrument, talking instrument effects can be created. Native Instruments Vokator is one such plug-in.

VST Plug-In - a program that uses Steinberg's VST technology to obtain digital audio samples which are then manipulated by applying reverb, compression or some other type of audio signal effect. The output signal may be rendered off-line or generated in real-time while the plug-in's host program performs playback.

VU Meter - Meter designed to interpret signal levels in roughly the same way as the human ear, which responds more closely to the average levels of sounds rather than to the peak levels. The Volume Unit Meter is designed to visually interpret signal levels in roughly the same way as the human ear, which responds more closely to the average levels of sounds rather than to the peak levels.


Wah pedal - Guitar effects device where a bandpass filter is varied in frequency by means of a pedal control.

Warmth- A subjective term used to describe sound where the bass and low mid frequencies have depth and where the high frequencies are smooth sounding rather than being aggressive or fatiguing. Warm sounding tube equipment may also exhibit some of the aspects of compression.

WAV- The computer file extension for a WAV file is ".wav.” This is the most commonly used uncompressed PC digital audio file format.

Wave - All sound moves as a wave, and the graphic description of a sound is known as a waveform, its shape determined by the levels (amplitudes) of the Fundamental Frequency, and (unless the wave is a pure Sine Wave) the harmonics which follow.

Waveform Editors - Software that allows waveforms to be manipulated through edits such as cuts, splices, loops, and redraws. Depending upon the sophistication of the software, one can edit extremely detailed amounts of data. Steinberg’s Wavelab, Adobe’s Audition and Sony’s Sound Forge are examples of excellent wavefrom editors for the PC. Read our guide to basic audio editing here.

Waveform - A graphic representation of the way in which a sound wave or electrical wave varies with time. A cyclic propagation of energy through a medium at a constant velocity. e. g. sound pressure waves through air, or a diagram of such oscillations. Also refers to the appearance of the oscillating voltage of an audio signal on an oscilloscope. See also Pulse Wave, Ramp Wave, Sine Wave, Square Wave, Triangle Wave

Wavelength - The distance between two identical points on a waveform i.e. one cycle of the waveform, or the spatial distance between two identical points of an electromagnetic or sound pressure wave which have the same phase. In high frequency waves, there are more cycles in a given unit of time than there are in low frequency waves, this means they are closer together and consequently the wavelength of a high frequency is shorter than that of a low frequency. The wavelength of an given frequency can be determined by dividing the speed of propagation of the wave by its frequency. For electromagnetic waves this is c/f, where c is the velocity of light and f is frequency, this gives a result in metres. For sound pressure waves it is approximately 334 m/s divided by the frequency in Hz, so that audio frequencies have wavelengths in the range from 16 metres to 1.6 centimetres.

Wavetable - A storage location that contains data used to generate waveforms digitally.

Wavetable Synthesis- A method of generating waveforms through lookup tables. Many software synthesisers use wavetable synthesis where these digitized waveforms are organized in a bank or table, accessed through a sequencer.

Wet signal - signal which has been processed in some way (by reverb, eq, or whatever). Opposite of "dry" signal.

White Noise - A signal which contains all possible audio frequencies in equal average amplitudes. Useful for testing equipment. A random signal with an energy distribution that produces the same amount of noise power per Hz.

WMA (.wma) - "Windows Media Audio", Microsoft’s proprietary compressed audio codec designed to compete with MP3. This format frequently includes the much maligned digital rights management access controls.

WMDM - Windows Media Device Manager is a Microsoft software component that enables Windows applications to share and transfer files to and from non-PC devices, such as portable MP3 players, in a standardized way. The use of a common software component enables greater software and hardware compatibility and support.

Woofer - A speaker that is used for low-frequency reproduction.

Word - One sample of audio data.

Wow and Flutter - This is when slight variations in the speed of a tape transport, turntable motor etc creates an annoying "wobbly" variation in pitch. Generally, the "wow" part describes the effect created by slower variations in speed over a longer period, whereas "flutter" describes sharper variations over a shorter period of time. You may find this control on plug-in delay effects such as Apple Logic’s Tape Delay.


XLR Connector - Short for "X-tended Locking Round" A professional standard, three pin balanced connection system, originally developed by the ITT and Cannon corporations. It is a standard connection for microphones, and frequently used for much professional equipment which requires balanced inputs and outputs. Many sound cards have XLR connections on the front panel for ease of use.


Zero Crossing Point - Sounds are primarily oscillations, and they oscillate around an axis known as the "zero crossing point". At this point the negative signal crosses over into being a positive signal, and vice versa. This point is represented in audio editing software as a horizontal line bisecting the editing window. When editing a sample it is always preferable that a waveform starts, and ends at a zero crossing to prevent audible “clicks” in the material post edit. Read our guide to basic audio editing here.