MIDI Glossary (Musical Instrument Digital Interface). MIDI Terminology. Table of MIDI terms and meanings. A resource of MIDI meanings.
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MIDI Glossary

(Musical Instrument Digital Interface)


MIDI Glossary (Musical Instrument Digital Interface). Musical Terminology. Table of MIDI terms and meanings. A resource of MIDI meanings.


ACTIVE SENSING : A feature that enables a receiving MIDI device to implement an All Notes Off message should it ‘sense' an interrupted communication from a controller, thus preventing notes from ‘hanging' in the event of broken communication. A very useful feature for a MIDI device to implement.

AD/DA: Conversion of an audio signal from analog to digital, or from digital to analog. This can be carried out at different resolutions, with different corresponding quality levels. It doesn't really impact on MIDI data, as such, which is by definition ‘digital.'

ADDITIVE SYNTHESIS: A type of synthesis that creates sound by combining (‘adding') harmonics at varying pitches and levels. A Hammond organ employs, in effect, an additive synthesis system with its drawbars.

ADSR : Attack, Decay, Sustain and Release. These are the four most commonly used segments of stages of a synthesizer's envelope generator. Attack controls the time it takes an applied parameter to reach its initial level. Decay controls the time it takes for that parameter to transition to a ‘sustain' level. Sustain governs the time an applied parameter will remain at the level to which is has settled Release controls the duration of an applied parameter to fade out once a ‘note off' is generated. While envelope generators are most commonly found as sections or panels on a synthesizer, MIDI does provide for (general) control over these parameters either using standard Continuous Controllers or via NRPN (Non-Registered Parameter Numbers).

AES/EBU : One of several professional formats for exchanging digital audio signals. In general terms, not something MIDI needs to worry about per se.

AFTER TOUCH : A parameter that measures the level of intensity applied to a note ‘after' it has been played and continues to be depressed. After touch can be polyphonic (different notes will respond individually in a cluster of held notes) or monophonic (one value will apply to all notes held down). Typically, after-touch is useful for adding vibrato or tremolo effects to a sound in much the same way that a violin can add volume or pitch changes to a sustained note using finger vibrato or addition bowing intensity.

AIFF : Proprietary file format for storing and transferring audio data on the Mac platform. Equivalent to a WAVE file on a PC.

ALL NOTES OFF : A MIDI channel message that tells a MIDI sound-generating device to shut off all currently active notes. This is a life-saving device to cure ‘hanging' MIDI notes.

ARPEGGIATOR : A device that generates a time-based series of control information - most commonly, pitch – so as to produce repeated phrases or motifs. Although the initial scope of arpeggiators was to produce a series of standard patterns based upon conventional scales and chord shapes, in recent years arpeggio algorithms can now generate highly complex data to create articulations including guitar strumming styles, drum patterns and more. Arpeggio algorithms may be preset or editable depending upon the device, and generally manipulate existing MIDI data in terms of pitch, duration, velocity, and timing.



BANDPASS FILTER : A type of Filter that eliminates both higher and lower frequencies around a specified ‘band' of frequencies. More inclined towards special effects than ‘natural' tonalities.

BANK: A collective storage location that houses multiple sounds, samples, patterns etc. In MIDI , an individual bank can hold up to 127 items. MIDI also allows for many different Banks to be selected using ‘Bank Select' commands.

BAUD : A measurement of speed at which serial data is transmitted. MIDI operates at 31.25 kBaud, i.e. data can be transferred at a speed of 31250 bits per second.

BINARY : A system of numbering using only the digits 0 and 1. This is the foundation of computer language and MIDI , too, uses a binary system.

BIT / BYTE : An abbreviation for 'binary digit,' a ‘bit' is the most basic unit of information used in any digital system, including MIDI . Generally there are 8 bits to a byte although MIDI adds additional two bits: one to signify start, the second, stop.

BIG-ENDIAN : Big-Endian and Little-Endian derive from "Big End In" and "Little End In." These terms refer to the order in which a sequence of bytes is stored in memory. Big-Endian order means that the most significant byte (MSB) value is stored at the lowest address and each next most significant byte is stored in the next location and so on. Little-Endian is the reverse - the least significant byte (LSB) is stored at the lowest address and the other bytes follow in order of increased significance.

BIT DEPTH: Bit depth is the number of bits (ones or zeroes in a binary number) that are used to describe digital data such as audio at a given point in time. One such point in time is a sample. Each added bit doubles the number of possible ways to describe each individual sample. A 16-bit sample can be described with any one of 65,536 values whereas a 24 bit sample has 16,777,216 possible values.

BUFFER : An area of RAM used to temporarily store data.

BUS: A signal route within a device or section of a device such as a mixer (software or hardware).



CENTRAL PROCESSING UNIT (CPU) : The brain of a computer device; the silicon chip that performs the devices major calculations. Inherently, MIDI does not put any significant load onto a CPU, though highly graphic audio-processing destinations such as plug-ins that MIDI is now asked to control certainly do.

CHANNEL: A MIDI Channel is a bus over which devices sending or receiving MIDI data can communicate. MIDI specifies that devices can specify or use up to 16 MIDI Channels (1-16) on any given port or network. In order to communicate, MIDI devices need to be set to the same MIDI Channel.

CHANNEL MESSAGES: MIDI messages carrying a channel number in the header byte. Most day-to-day MIDI messages are Channel Messages, i.e. Note On, Note off, Program Change etc. Global MIDI data that is not channelised comes under the title of a System Message.

CHORUS: An audio effect that superimposes two or more versions of a sound upon itself at different pitches, so producing a thicker, sometimes ‘swirling' effect. Since it is so commonly used, MIDI has specified a dedicated Continuous Controller (# 93) for chorus amount.

CLOCK: A regular series of electronic pulses that control the tempo of time-based devices (sequencers, drum machines etc). MIDI Clock—which substitutes pulses for MIDI clock messages—is a method by which two or more such devices can play in sync by choosing one device to transmit these messages and the other(s) to receive clock information externally (i.e. from the designated master device.)

CONTINUOUS CONTROLLER: A MIDI message tailored to parameters that require a range of multiple values such as modulation depth or volume. CCs can be controlled in real time by knobs, sliders, wheels, etc. or can be input as a series of parameter values into a MIDI sequence.

CONTROLLER: A MIDI controller is a device that transmits MIDI data. This can be as simple or as complex as required by the particular device and can range from keyboards (typically dedicated MIDI controller keyboards only control and do not generate sounds); to ‘alternate' MIDI controller instruments like MIDI guitars and wind instruments; to sensor-based devices such as knobs or sliders, or even gloves, pads, control surfaces etc.



DEFAULT SETTING: The state of a setting when a device is purchased or powered-on. Also called "factory setting" or "initial setting." Most devices have a ‘reset' function whereby settings can be returned to their default state.

DELAY: As an effect, one that creates or simulates the time difference between direct and ‘reflected' sounds. MIDI delays, similarly, manipulate note data to mimic the effect. MIDI delays can also be a phrase used to describe the less desirable lag between MIDI messages being sent and being received and acted upon.

DIGITAL AUDIO : The representation of sound as computer data. In order for (analog / real live) sound to be digitized, it needs to be converted via an A-D (analog to digital) converter. In order to hear digital audio, the data then needs to be converted back in to analog via a D-A (digital to audio) converter. The quality of digital audio is dependent upon many things, from the quality of the A-D and D-A, to the resolution and bit depth of the digital audio data itself.

DIGITAL SYNTHESIS : A method of synthesis that uses numbers, rather than variable ‘analog' circuitry to generate and control sound.

DIN CONNECTOR : The original connection device used to send and receive MIDI data. MIDI used—and still can use—the 5-pin, 180-degree DIN connector, although only 3 of the pins are actually employed for MIDI communication.

DIRECTX PLUG-IN: Plug-in standard for instruments and effects originated by Cakewalk for use in the company's DAW applications.

DRUM MACHINE : An electronic device dedicated to drum sounds and the generation of drum patterns. Drum machines originated from organ accompaniment systems developed in the 1960s and came of age just prior to MIDI with the first digital drum machine from Roger Linn. The hugely popular Akai MPC series drum machines, initiated by Linn designs, fueled the beats the would go on to define hip hop, though, ironically, the sounds themselves harked back to the days of synthesized drum sounds made popular via such drum machines as Roland's TR-808.

DSP : Digital Signal Processing. A number-crunching process that creates ‘effects' (reverbs, delays, chorus etc) by altering the output of digital audio.

DYNAMICS : Fluctuations in volume, i.e. the difference between the highs and the lows. Dynamics can be essential to create music that sounds ‘real' and not overly electronic. Conversely, dynamics can also need reigning in to produce music that sounds consistent and ‘loud.'



ECHO: A delay long enough for two or more sounds to be discerned as separate events. Generally the delay needs to be at least 50 milliseconds to produced an echo effect.

ENVELOPE: A term used to describe the overall shape of a sound's tone, pitch, or volume. ADSR (see entry) are the most commonly used parameters in a synthesizer's envelope generator.

EQ : Equalization. An audio processing device used to cut and boost individual frequencies present in a sound so as to change its tone. The name originated from its initial purpose to make a sound more natural, balanced, or equal.

EVENT : A separate and specified MIDI message, be it a Note On or Note Off, pitch bend data, or a Program Change. Some devices (notably sequencers) may quantify their capacity in terms of ‘events' as opposed to notes, which can create misleading impressions since a single note might have several hundred MIDI events attached to it if after-touch, pitch bend, or modulation is employed extensively.


FADE IN/OUT : Though more commonly applied to audio, where actual volume or amplitude gradually increases and decreases, either MIDI Controller 7 (Volume) or 11 (Expression) messages can be used to create fade-ins/outs via a succession of parameter values that progressively increase or decrease from 0-127. If a fade-in/out is needed for an entire track comprising multiple MIDI Channels, the Controller messages will need to be applied to all channels being utilized.

FADER : A slider generally found on mixers (hardware or software) used for attenuation - gradual, smooth control over the signal under its control. Faders can also be employed to generate MIDI Controller messages for similar control over a MIDI source.

FILTER: In audio terms, a filter literally filters out certain frequencies in a signal or waveform in order to alter its tonal characteristics. Low, High, and Band pass filters let these frequencies pass through, filtering out the others. MIDI Continuous Controller messages (CC # 74 Brightness' and 71 ‘Resonance') can apply filtering to MIDI sound sources (commonly most GM sound sets) that respond to this parameter. A MIDI filter can also refer to a device that filters MIDI data as opposed to audio frequencies.

FILE FORMAT : How data is organized in order that it can be recognized by particular applications or devices. Standardized file formats such as .WAV and .MID (Standard MIDI File) enable data to be transferred between applications made by different manufacturers so long as they share the same basic functionality (a MIDI sequencer, an audio engine etc.).

FSK: An older method of timing synchronization involving fluctuating pitch. Stands for Frequency Key Shifting. Though stable, and effective, it did make a particularly nasty ‘dentist's drill' type of noise.



GENERAL MIDI (GM): A standard developed in the early 1990s based around sound types. It enables sequences (stored in .MID format) to be played back on any ‘GM' sound sources and sound at least ‘OK.' The establishment of a unified system of ‘Program Change' #s allows piano parts to call up piano patches, acoustic guitar parts, acoustic guitar patches, and so on.

As with most things MIDI 128 basic sounds are specified, with provisions for additional sound subsets that can be offered on more sophisticated devices.

Championed initially by Roland, whose Sound Canvas modules quickly became the de facto GM soundset, GM was for a long time the savior of both the game audio and cell phone industries where standardization was key. Though not as vital as it was in the 1990s, GM is still a useful tool for transferring song files, and the GM drum map (specifying which keys trigger which drum sounds) continues to be the norm on all but the most sophisticated synthesizer drum voices.


HARDWARE : A physical piece of electronic equipment from a computer to a musical instrument. In order to ‘do' something, hardware requires ‘software' for instructions.

HEXADECIMAL (HEX) : A system of numbering based on 16 (as opposed to 10 on regular decimal systems). In addition to 0-9 the letters A-F are employed. MIDI codes are most commonly supplied in this format.


KEYBOARD SPLIT : The place where a keyboard is set up to trigger two or more different voices across its range.

KILOBYTE (K) : Measurement of storage capacity or size in a computer, computer disk, or file. A kilobyte is 1000 bytes of data.



LIBRARIAN : A program that organizes and/or stores sets of voice data for synthesizers or other instruments, enabling sounds both to be stored safely and externally for backup, and also to enhance the storage capacity of the synth/instrument itself. MIDI (Bulk Dump) is generally used for loading and saving of such data.

LITTLE-ENDIAN: See Big-Endian.

LOCAL ON/OFF : MIDI Channel Message that sets whether your keyboard is going to trigger its internal sounds (Local ON) or not (Local OFF). This is a vital parameter to have control over in order to avoid loops and double-triggers when your keyboard is part of a larger, computer-involving rig of equipment.

LOOP : As it sounds, where music or data repeats endlessly. Sometimes this is a good thing, as in a drum loop or a musical refrain. A loop point in a sample is where the end meets the beginning again (and which you want to be as seamless as possible). A loop can be undesirable where data feeds back on itself as in ‘feedback' with audio. Unlike audio, which can indeed be desirable, a data loop will generally cause a device or program to wig out and probably crash. If you have such control at hand, a MIDI Reset command can provide a cure.

LOW FREQUENCY OSCILLATOR (LFO) : Synthesizer module or parameter that uses ultra low frequencies (beyond audio range) to modulate another parameter such as volume, pitch, or tone.

(LEAST SIGNIFICANT BYTE) LSB: This refers to the byte of least potential value in a multibyte number such as a number sent as MIDI control data.


MASTERING : The process of final adjustment - to overall tone, volume, and possibly effects - before a recording is ready for publication or duplication.

METRONOME : Originally a physical, mechanical device featuring a ‘clicking' and speed-alterable pendulum, used to help musicians set – and keep – strict time when they play. Within DAWs, a metronome facility is available, driven by MIDI Clock.

MIDI ADAPTER: A sound card MIDI adapter cable lets you connect MIDI devices to your computer via the computer's joystick port.

MIDI CABLE : Standard cable used to connect MIDI devices featuring 5-pin DIN connectors on both ends. MIDI can also be transmitted by other means (cables): USB, FireWire, and indeed wireless.

MIDI CHANNEL : MIDI data is communicated using a system of 16 discrete 'Channels,' each of which can be used to send and receive specific commands between connected devices. When making connections between instruments/computers/devices, you normally will choose a MIDI Channel (between 1-16) on which you want to communicate. On DAWs, you will frequently want to utilize several MIDI Channels; one for each track of a song. You may also need to utilize several MIDI ports; each of which can communicate using their own 16-channel system.

MIDI CHOKE : When too much MIDI data is being transmitted or received simultaneously. Results of this can vary; from impaired timing, to failure of all notes to trigger, to system lock-up. The cause can simply be too much data on the move, or be caused by incorrect connections or settings causing a MIDI data loop. A cure may be found by sending Reset or All Notes Off messages, or your set-up may require re-patching / re-cabling.

MIDI CONTROLLER : Any electronic device that can generate and send MIDI data. Most commonly seen are MIDI keyboards, but there are many others: MIDI guitars, MIDI drum pads, MIDI wind controllers, boxes of knobs, gloves, and more. All non-keyboard controllers are often referred to as ‘alternate' MIDI controllers.

MIDI DATA : Catch-all term for any and all information being communicated between MIDI devices.

MIDI DEVICE : Generic term for any MIDI-enabled piece of hardware or software from a synth to a sound module, interface, controller etc.

MIDI FILE : Abbreviation of ‘Standard MIDI File' (SMF): sequencer files that adhere to the protocols of SMF format. Most DAW/sequencer applications can, in addition to generating their own proprietary file formats, save and load sequences in this easy-to-transfer format.

Though not compulsory, most MIDI Files will also use the GM system of note-mapping (for drums) and sound assignments in order that they can be played back on a wide range of systems and soundsets.

MIDI IN, OUT, THRU: Names and functions of the MIDI ports found on most MIDI devices. MIDI IN will accept incoming data only. MIDI OUT will transmit data. MIDI THRU passes on data that is being received at the IN port to another device.

MIDI INTERFACE : The point or points at which MIDI data can be connected to a device. Most computers do not sport MIDI as standard, and therefore will require some type of (additional) MIDI interface in order to handle MIDI data.

MIDI KEYBOARD: An electronic keyboard that possesses the ability to send and receive MIDI data. Micro switches beneath the keys connect to a MIDI processor where such information as note, duration, and velocity (key speed/strength) can be processed.

MIDI PORT : The point or points on a MIDI device where you connect to other MIDI devices. Initially, 5-pin DIN connectors were used exclusively. A MIDI port could also be USB/FireWire nowadays.

MIDI SEQUENCER : Most commonly, software (though in the past hardware too) applications or devices used for the assembly of musical compositions. A musical word-processor, if you like. The word ‘sequencer' is now not used so often as Digital Audio Workstation, a somewhat grander sounding name for sequencers that now also possess the ability to handle audio and a myriad other processing tasks.

MIDI CLOCK : Real-time System message that drives and can synchronize performance data in and between MIDI devices. MIDI Clock operates at 24 ppqn (pulses per quarter note) or ‘divisions' per beat.

MIDI MERGE : A device that accepts MIDI data from various sources and merges it into a single (output) source.

MIDI MESSAGE : Packets of data that form a MIDI transmission.

MIDI TIME CODE (MTC) : System comprising the information contained in a SMPTE signal in MIDI form that can be recognized by MIDI devices. Not all MIDI devices may implement MTC, however.

MIXER: Hardware or software device that takes multiple individual audio sources and enables their combination into a grouped or ‘mixed' signal.

MIDI MACHINE CONTROL (MMC): Group of MIDI messages used to control recorder operations such as Play, Stop, and Record.

MODWHEEL : Wheel controller found on synthesizers that players can use to progressively introduce modulation depth to a sound. The mod wheel itself can normally be assigned to many different parameters selected by the user, though it is most commonly applied to pitch in order to produce vibrato.

MONO: A word that has a great many definitions, but in a purely MIDI context it signifies that only one note per channel is possible. MIDI Modes 2 & 4 assign mono one voice unilaterally and one voice per multi-timbral MIDI channel, respectively.

MONITOR : As a verb, to listen to a sound; As a noun, a speaker. As a collective noun, a complete system that enables performers on stage to hear themselves (as in a monitor system).

MODULATION: Literally, to add movement to a sound - normally via an LFO. A mod wheel is a device that governs modulation amount or intensity.

MSB (MOST SIGNIFICANT BYTE): This refers to the byte of highest potential value in a multibyte number such as a number sent as MIDI control data.

MULTI-TIMBRAL: The capacity of being able to generate multiple (and different) voices simultaneously, each controlled on its own MIDI Channel.

MULTITRACK : The capacity of being able to house (and so record and play back) multiple tracks in a recording device, such as a sequencer or DAW.

Anything other than multitrack devices are fairly rare outside of little play sequencers on home digital pianos.



NOTATION PROGRAM : Programs that focus on presenting music data on a stave, in ‘conventional' notation form. Almost exclusively, input to such a program (or indeed a notation feature within in DAW) is via MIDI .

NOTE ON/OFF COMMAND: A Channel Voice Message indicating when a note is to begin sounding and when the ‘fingers are taken off the keys.' Depending upon the envelope of the voice being triggered, a Note Off message may not necessarily result in the sound actually stopping of course.

If you are doing a lot of editing, cutting and pasting, it is important to keep an eye on your Note Off commands (not normally displayed as a default on most DAW platforms) because it can be easy to make an edit to a note before its Note Off message, which can lead to hanging notes and messy sounding loops, or, on certain platforms, irregular bar lengths being displayed. Motto: keep an eye on your Note Offs when cutting and pasting.


OMNI : A word (latin for ‘all') used as a descriptor for some of the ‘modes' that MIDI devices can choose to operate in. Omni ON signifies a device will respond on all MIDI channels. In Omni OFF (poly – Mode 3) a device only responds to a single, predetermined MIDI channel, and in Omni OFF (mono – Mode 4) each voice can be assigned to its own MIDI channel.

OSCILLATOR : The circuitry that generates the kernel of a synthesizer sound. In the early days oscillators generated a fairly basic of sound types (sawtooth, square, pulse etc). In modern synth engines oscillators can be driven by a myriad waveforms and samples.


PAN: A term derived from "panorama," referring to a parameter that specifies the location of a sound within the stereo field. Normally if a sound that is originally stereo is assigned to two monaural channels, the pan controls of the two channels are set to far left and far right so that the sound can be monitored in its original spatial state.

PARAMETRIC EQUALIZER : An EQ (set of tone controls) that offers variable control over a range of frequency bands, each with a cut or boost control.

These frequency bands normally work in parallel, and allow the user to pinpoint a frequency that requires attention by sweeping the frequency (turn up the boost to max and then adjust the frequency control in the general area of what you need until the troublesome frequency really jumps out) and then making the necessary adjustment.

PARAMETERS : Individually controllable elements of a device or instrument. Filter cutoff is a parameter. So too is envelope attack, or feedback level on a reverb.

PATCH: A throwback to the days of modular synthesizers when different modules and parameters within them could be connected using (physical) patch cords. The final sound that resulted from frequently multiple patching, eventually came to known as a ‘patch.' Fast forward to modern synthesizers and the word is now used to describe any single and identifyable ‘sound' as in a brass ‘patch', a piano ‘patch' etc.

PITCH WHEEL : A wheel type device, normally found to the left of a synthesizer keyboard, used to manipulate the pitch of a played note or notes.

PITCH BEND : A Channel Voice Message or activity or message, generally initiated by a pitch wheel (though any other controller set to manipulate pitch will do), that smoothly raises and/or lowers the pitch of note or chord. This can be achieve in real time during a performance, or can be recorded into a sequence. Unlike data for volume, or note #, pitch bend uses a complex string of data, making it difficult to ‘edit.'

POLY : Short for polyphonic. The state of being polyphonic indicates a musical device's capacity of playing multiple notes at a time.

PORT : A connection point.

PLUG-IN: A term first used in graphics programs but subsequently adopted by music software used to describe small(er)computer programs designed specifically to work inside (or sometime alongside) a host application. Plug-ins are designed to provide additional content or functionality for the host program.

TDM plug-ins for ProTools were the first to appear, though soon after Steinberg developed the universally adopted VST standard. Other plug-in standards include DirectX and RTAS.

PRESET: A patch or program on a device that cannot be overwritten.

PROGRAM CHANGE: A Channel message (from 00-127) that tells a device to switch to a particular patch/voice/preset etc. A Program Change message can – indeed should - be accompanied by a Bank Select message since MIDI can specify many different banks of 128 programs. Without adding a Bank Select command, a receiving device will simply move the Program Change # indicated within its currently selected bank.

It is essential that Program Change messages are placed at the beginning of GM sequences (MIDI Files) in order that piano parts will be played back on piano sounds, guitar parts on guitar sounds etc.

PUNCH-IN/PUNCH-OUT: The process of quickly going in and out of ‘record' on a track, often done when a passage needs to be re-recorded within a longer part that is otherwise OK (i.e. a repair), or when a part comes in mid-song.


Q : A parameter found both on filters and on parametric EQ devices but indicating slightly different things. On a synth filter, the Q relates to resonance: an amount of signal boost at the cutoff point that creates a whistling, ringing, resonant effect. On a parametric EQ, Q indicates the width the frequency band to be boosted or cut. A narrow Q focuses in sharply on a particular frequency while a wide Q setting will make broader tonal adjustments (treble, mid, bass).

QUANTIZATION : Within a MIDI sequence, the automatic adjustment of timing values to some formula or pattern other than the one originally recorded. At its most basic level, to quantize a passage to sixteenth notes will drag all notes to their nearest sixteenth note, so making the passage sound both very in-time, but also very stiff and mechanical. There are many more subtle settings and styles that can both ‘correct' timings, in a more natural manner, and even create human feel ‘groove quantizing' where none originally existed.

In digital audio, the term indicates the resolution of a recorded signal, as in 16-bit or 24-bit quantization.

QWERTY KEYBOARD : ‘Typewriter' or computer keyboard as opposed to a musical keyboard. The word QWERTY is what's spelled out by typing the first six letters on the top row.


RAM : Random Access Memory. Temporary storage medium that operates only in the present, i.e. it gets cleared when the computer or instrument is switched off. If data currently stored in RAM needs to be saved permanently, it needs to be saved to a hard drive or other external storage device such as USB stick etc.

REAL TIME : As it sounds, an action or process that is executed live, as it happens. Real-time recording on a sequencer or DAW records actual performances as opposed to ‘step-time' recording where data is input piecemeal. Real-time controllers provide instant ‘live' control over some aspect of a sound or performance.

RECEPTION MODE : How a synthesizer responds to incoming data.

RELEASE : Generally final stage of an envelope generator governing the duration of an applied parameter to fade out once a ‘note off' is generated. Setting a long release time makes a sound die away slowly while a short release will make it disappear the moment your fingers are lifted off the keys.

RESAMPLE : The process of recalculating a sample at a different rate than that used for the original recording. Resampling (at a lower rate) may be necessary to reduce file size. Depending upon the nature of the sound this may or may not have an adverse effect on perceived sound quality.

ROM : Read Only Memory. Permanent storage type in a computer or electronic musical instrument that cannot be overwritten. Synth presets, and waveforms used to create sounds, are stored in ROM.

REVERB: An effect that recreates the ‘reverberations' or sound reflections found in various contained physical spaces. Adding such reflections thus creates the impression that a sound is taking place in a large concert hall, small room, in the Grand Canyon etc etc . General MIDI offers CC#91as a universal Send Level control for reverb. Additionally data for certain reverb types and reverb lengths can be programmed into a GM MIDI File.



SAMPLER : Samplers are very similar to synthesizers , with the ability to add or create custom samples. Samples are digitally recorded sounds of actual instruments, human voice or any kind of noise you like. These samples can be triggered from MIDI sequencers or MIDI keyboards .


SAMPLE: A sound bite – either a rhythmic loop or a static sound - stored as a digitized waveform in a computer, or sample-enabled synthesizer. A sample can also refer to single slice of a digital audio wave.

SAMPLER: Computer application or hardware device that can record, manipulate and play back digital audio. A sampler can be triggered either directly from a MIDI controller, or via MIDI Note-On messages stored within a sequence.

SAMPLING RATE : The resolution at which a sample recording is taking place. Sample rates indicate of the number of times per second that the audio is being converted into digital data. Logically, higher numbers offer higher resolution, and so higher quality (more accurate) results. The higher the sample rate the higher the memory requirement, so there often needs to be a trade-off. Higher sample rates may not be needed (because they won't make any difference) when sampling individual sounds that don't contain many high frequencies. Ideally the rate should be twice the highest frequency you're recording. CDs are recorded at 44.1kHz which translates to 44,100 samples per second.

SCSI (SMALL COMPUTER SYSTEM INTERFACE) : A specification (with attendant connecting devices) used to transfer data between a computer and an external storage device. This type of connectivity has now largely been replaced by USB and FireWire.

SERIAL : A form of communication that transmits information sequentially, i.e. one piece of information (bit) after another. MIDI uses this form of communication. The opposite is a Parallel system, whereby data is transmitted simultaneously.

SEQUENCER: A musical word processor: a software application, or feature found on a hardware keyboard workstation, that can record, process, and play back MIDI events designed to be trigger sound-generating devices or software for the purposed of recording complete pieces of music. Though sequencing began life as a MIDI-only entity sequencers eventually embraced audio recording as well. Modern software devices that can record, process and play back both MIDI and audio are now generally referred to a Digital Audio Workstations or DAWs (pronounced ‘doors').

S/PDIF : Stands for Sony/Philips Digital Audio Interface. The specification is formally called IEC60958, but is more generally known as S/P DIF, and is a consumer format for transferring digital audio signals. S/P DIF simultaneously transmits or receives two channels of audio.

SOLO: A multi-faceted word variously used to describe the action of listening to the sound of only one channel or track in a mix, a sound (generally a monophonic one) to be used for melody lines, or a free-form instrumental passage in a song (guitar, drum solo).


TEMPO : The speed at which a song or loop plays. Tempo can be set, and can be programmed to vary over the duration of a song in order to create a more natural human feel, using MIDI Clock.

TICK:  The smallest increment of a beat; based upon the resolution of the device or application being used.

TIMBRE: Tone characteristics or color.

TREMOLO : Steady fluctuation in volume; used for and as an effect.

TIME CODE : Time data used to synchronize devices.

TRACK : A separately accessible and controllable location for housing recorded data in a song. Current DAWs generally offer unlimited MIDI and Audio tracks on which parts can be recorded.

THRU : The MIDI THRU port passes ‘through' to the MIDI OUT port data that is being received at the MIDI IN port. ‘Soft' THRUs are OUTs that can be configured as a THRU whenever necessary.

THRU-BOX : For units that don't have a THRU port you can purchase one of these physical boxes. Generally they will provide a MIDI IN socket and several THRU output ports.


USB MIDI: Where MIDI is being delivered via a USB interface.


VELOCITY:  Measurement of the speed – and so in practice the intensity and resultant volume , that notes are being played. MIDI provides for velocity levels from 0-127.

VOICE EDITOR : This provides computer-based, on-screen access to the controls of a sound source. Changes in setting are generally sent to the instrument via MIDI instantaneously in order that adjustments can be made and heard in real time.

VOCODER: A ring-modulator-based audio effect that creates robotic effects. Mainly used with a human voice as a sound source; with notes or chords played on a connected keyboard determining the pitch.

VST PLUG-IN : “Virtual Studio Technology:” an initially Steinberg (but now widely adopted as standard) format the creation of instruments (VSTis) and effects (VST fx) used within a DAW environment. Although the results of these plug-ins are audio-based, they are MIDI-driven and operated.


WORD CLOCK : A synchronization signal used when transferring digital audio data; used to ensure that the audio data is received at the same rate it is being transmitted. When multiple devices are digitally connected, all need to use the same word clock to avoid problems of audio transfer and, most likely, unwanted noise in the signal.


XLR CONNECTOR : A professional three-pin connector primarily used for mics. It has a locking mechanism that prevents the cable from being pulled out accidentally. It can also be used for MIDI though this is not common.


MIDI Manufacturers Association (MMA)

MIDI is a trademark of MIDI Manufacturers Association Incorporated.

About MIDI - Making Music with MIDI - MIDI Controllers - MIDI Products - MIDI Glossary - MIDI Polyphonic Expression (MPE)

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