Music Technology Glossary
- Aftertouch – Pressure changes applied to a key after the initial strike.
- Antinode – The point on a wave of greatest displacement.
- Ampere – Unit of measurement of electrical current, named after the French physicist Andre Marie Ampere.
- Amplification – Usually refers to the process of increasing the magnitude (amplitude) of a signal whilst retaining the shape/integrity of the original waveform.
- Attenuation – Reducing the amount of some quality of a signal, most commonly referring to the gain/volume of a signal. This is the opposite of amplification.
- Attack – The speed with which an action occurs – this can be applied to a variety of actions, such as playing a note or applying compression. Generally, a soft string pad will have a very slow attack, whereas a drum hit has a very fast attack.
- Audio Frequency – The range of audio frequencies directly detectable by the human ear ranges from about 20 Hz to 20 kHz (20,000 Hz). In practice, this is actually closer to 20-17 kHz. Dolphins are believed to hear up to 70 kHz.
- Binary – Base two (using two digits to count). The common decimal system (base 10) uses ten digits to count (1-10), and hexadecimal uses 16 (1-10 and A-F).
- Buffer – In memory terms, this is an area of RAM used to store data (audio) before passing it on to the hard drive to be written.
- Clipping – This occurs when an audio signal exceeds 0dB – in the digital environment, the signal is truncated at 0dB, resulting in a harsh square wave form of distortion. Analog clipping can sometimes be a desirable effect, as it sounds much ‘softer’.
- Channel – MIDI data is passed through channels, each of which can be routed independently. For example, you can set up your system so that one channel controls a piano instrument and another controls a drum kit.
- Choking – When too much data gets passed to a particular device at once (bottleneck).
- Compression – In its most basic form, this means the attenuation of a signal above a set threshold. If the peaks are reduced in a recording, the overall (RMS) level of the recording can then be made higher (louder).
- Concert Pitch – Established by the International Organisation for Standardisation in 1955, the agreed reference frequency of 440 Hz for the note called middle A (the A above middle C).
- Controller – A device that uses MIDI to control external parameters. A keyboard can be used to play an outboard synth, a drum pad can control a drum machine, and so on.
- dB SPL – The unit of measurement for sound pressure level (SPL). In layman’s terms, it could be described as the smallest variation in volume detectable by ear. 0 dB = 20µPa (micro Pascals). The human range of hearing is related to this scale with 0 dB (SPL) being the threshold of hearing, and 120-140 dB(SPL) being the threshold of pain.
- Decibel – A ratio-based measure of the amount of some quality (usually sound level, power or voltage) relative to a set reference amount. It is often qualified to indicate what property is being compared, such as dB(A) or dB(v). A signal-to-noise ratio of 80 dB(v), for example, compares the amplitude of the signal (which we want to hear) and the noise (which we don’t). The signal voltage then becomes the reference point, and so would be called 0 dB(v). The noise voltage would therefore be 80 dB(v) smaller. The logarithmic nature of the decibel allows us to compare two values of enormously different magnitudes with conveniently small numbers. For example, the limits of hearing in terms of absolute pressure level cover the range from 20µPa to 200,000,000 µPa. The same range can be expressed in dB SPL as 0-140 dB SPL.
- Diaphragm – A thin membrane. The diaphgragm featured in a condenser microphone converts sound energy to electrical energy, whereas the diaphragm of a loudspeaker performs the reverse process – converting an electrical signal into audible sound. The diaphragm is also a human respiratory organ located beneath the lungs.
- Eigentone – Standing waves or acoustical resonances in an enclosed space may create notes (particularly bass notes) that are not in the actual recording.
- Envelope – Properties of a sound, attack, sustain, decay, release.
- Equalisation – Modifying a signal by boosting or attenuating specific frequency bands (EQ).
- Filter – A low-pass filter allows frequencies below the threshold to pass through, and a high-pass filter allows frequencies above the threshold to pass.
- Frequency – A measure of the number of waveforms that pass a particular point (per second). It is measured in Hz (cycles).
- FSK – Frequency Shift Key. Enables instruments to synchronise with a tape track.
- Gain – Boosing an audio signal.
- General MIDI (GM) – A standard set of instruments (0-127) following the GM template.
- GUI – Graphical User Interface.
- Headroom – Simiar to dynamic range, this is the amount of ‘room’ in dB between the RMS (average) level of a recording and the point at which distortion begins to occur.
- Interface – In DAW terms, an audio interface is basically the same thing as a sound card. As many interfaces are now external, the ‘card’ format is not strictly accurate.
- Marker – A signpost used to indicate a particular point in a recording. In Sound Forge, for example, pressing M during playback will place a marker at that point. Markers can also be used to define regions.
- Mapping – The process of matching up physical controllers with the appropriate function.
- MIDI – Musical Instrument Digital Interface.
- Multi-timbral – The ability to playback multiple tones simultaneously. Nowadays this is a fairly trivial capability.
- Notation – The writing down of musical information (sheet music). There are various ways of doing this; standard musical notation features a treble and bass clef, and a variety of standards for defining tempi and note duration. Guitar tablature is another way of writing down music, and drummers have their own notation also.
- Pan – Otherwise known as ‘balance’, this is the left-right position of a signal in the stereo field. Pan knobs on a mixer are known as ‘pan pots’.
- PCM – Pulse Code Modulation. An audio recording standard.
- Pitch Bend – This parameter can be controlled via MIDI, causing the pitch of a signal to go up or down.
- PPQN – Pulses Per Quarter Note.
- Quantisation – Most sequencers allow quantisation to be set at various levels; basically, it forces notes to move towards particular lines in the timeline. At 100% and 1/8 settings, all notes quantised will sit at one eighth divisions of a bar. At 50%, the notes will move 50% closer to these divisions.
- RAM – Random Access Memory. The more the better.
- Sampler – A device which records and stores audio chunks. These can then be manipulated in a number of ways.
- Sequencer – A device (hardware or software) that can arrange performance information on a timeline.
- SMPTE – Society of Motion Picture and Television Engineers. SMPTE time code is used to synchronise audio and video.
- Sound module – A device which generates sound but requires external control (such as MIDI).
- Synthesiser – A device which can be programmed to output unique sounds according to a variety of parameters.
- Velocity – The speed with which a keyboard key is struck. Used to determine how ‘loudly’ the note is played. More expensive MIDI keyboards are also pressure sensitive (providing more faithful reproduction of staccato performance, for example).