A glossary of terms taken from:

The Studio Musicians Jargonbuster: a dictionary of music and sound.
The Studio Musician's Jargonbuster (ISBN 0 9517214 2 9) - scrupulously written by me, carefully published & distributed by Musonix.co.uk, and easily available from any music shop which doesn't suck, or Musonix.co.uk itself.

 

Ambience
The reverberant quality of a room.

Amplitude
The relative value of a signal, its volume or magnitude. The height of its waveform.

Anechoic
Without echo. Said of an acoustic which is free field (i. e. without boundary or reflecting surfaces), and specifically of a room which is designed to produce no reverb or other echo effects. This is achieved by making the walls with very irregular surfaces of considerable and varying depths, in such a manner as to ensure that (in theory) all sound pressure waves which strike the walls are completely absorbed. Rooms of this type are used to test audio equipment such as loudspeakers and microphones and for other types of research.

Attack Time
(1) The time taken for a musical or other sound to reach maximum loudness or timbre from silence. The start of a sound. (2) Of a compressor or limiter etc. The time the device takes to respond to a transition in the signal level beyond the threshold. (3) Of an envelope generator the time taken for the envelope to reach its maximum level from its off or zero position. If the EG is being used to control an amplifier (VCA or DCA) the time taken to reach maximum loudness from silence.

Attenuation
A reduction in the the amount of some quality such as signal level. The property exhibited by attenuators. The opposite of amplification.

Audio Frequency
The range of frequencies which can be experienced by an average human being. The range is defined as 20 Hz to 20 kHz for convenience but in practice, is realistically closer to 20 Hz to 17 kHz. Dolphins are believed to hear up to 70 kHz.

Bandwidth
(1) 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. (2) One parameter on a parametric equaliser.

Concert Pitch
Established by the International Organisation for Standardisation in 1955, the agreed reference frequency of 440 Hz. for the note called middle A. Notated A=440.

Consonance Dissonance
An aesthetic judgment of the relative attractiveness of combinations of notes sounded together. Consonance relates to a more pleasant experience for the listener while dissonance relates to a less pleasant experience. The judgment of whether any given interval falls into one category or the other has been arbitrarily applied throughout history, with a general tendency for the progressing acceptance of smaller intervals. The terms are also used in a stricter sense in theories of tonal harmony.

dB SPL
A decibel based unit intend to give an absolute measurement of sound pressure, where 0 dB ="20µPa (micro Pascals). The human range of hearing is related to this scale with 0 dB(SPL) being the threshold of hearing, while 120-140 dB(SPL) (depending on which reference book you use) being the threshold of pain.

Decibel
A ratio based measure of the comparative amount of some quality, usually sound level, power or voltage, relative to some reference amount. It is often qualified to indicate what property is being compared i. e. dB(A), dB(v) etc. e. g. One might talk about a signal to noise ratio of 80 dB(v). This would be a comparison between the amplitude of the signal (which we want to hear) and the noise (which we don't). In this case the signal voltage becomes the reference point, (whatever the actual value was) and would be called 0 dB(v), the noise voltage (whatever the actual value was) 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. e. g. the limits of hearing in terms of absolute pressure level cover the range from 20µPa to 200,000,000 µPa. Any arithmetic on this basis is quite tedious. The same range expressed in dB SPL is 0 -140 dB SPL. Much more convenient.

Dynamic Range
The difference in signal level between the loudest and quietest parts of a programme, expressed in decibels.

Envelope
The characteristic change in amplitude throughout time which all sounds possess. The envelope of a sound has a number of features: whether it sustains like a bowed violin string; whether it decays like a plucked violin string or a single strike of a drum; and how quickly the sound reaches its fullest intensity - how the sound "attacks". While the envelope of any specific sound has specific characteristics determined by the way the sound was generated, it should be realised that real sounds occur in real situations and the envelope of a sound will change according to the environment it occupies. A clave in a cave may appear (what is the sonic equivalent of the eye-based "appear"?) to have a longer envelope than when it is played in the open air.

Envelope Generator
A device which produces a control signal which varies in level with time. The simplest of these (sometimes called ADSR) has four parameters: Attack Time, Decay Time, Sustain Level & Release Time. Thus it has three time constants and one level constant. Such a device is often found on synthesisers, where it is usually used to control the volume of an amplifier, the cut off frequency of a filter, or the frequency of an oscillator. More complex arrangements involving a series of time and level constants are available, particularly on digital synthesisers. These are called multistage envelopes and may involve eight or more parameters usually in time and level pairs.

Equal Temperament
A system for dividing an octave into 12 pitch steps, each of 100 cents. This has the effect of making all semitones equal in size. This became necessary once keyboard and fretted instruments became popular. It should be understood that the note A which appears in F# minor should have a slightly different frequency from the note A which appears in C major (this fine distinction is one of the reasons that pitch and frequency are not quite synonymous). This would normally be dealt with automatically by a proficient player on an instrument with continuous pitching such as a violin. A keyboard instrument would properly have to be tuned to a particular key, if music was then played in a different key, some or many of the intervals sounded would be flat or sharp. However since it was not convenient to retune these types of instruments correctly whenever a new key was required, various compromises were attempted. Equal temperament was one such compromise whereby the error was distributed equally between all the notes. This made the performance of music in different keys possible on the same instrument without retuning, in celebration of which J. S. Bach wrote not one, but two books, each of 24 preludes and fugues (a prelude and fugue in both the major and minor forms of 12 keys).

Frequency
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. Measured in units originally called cycles per second (CPS), now called Hertz (Hz). 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).

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.

Fundamental
The lowest frequency partial which is present in a (normally) musical sound. See also Harmonic, Inharmonic.

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. See also Inharmonic. (2) of or pertaining to musical harmony (the juxtaposition of one note with another or others).

Hertz
The SI unit of frequency, in particular the number of times something occurs in one second, abbreviated Hz. Named after Heinrich Rudolph Hertz (1857-94). The unit is sometimes alternatively expressed as CPS.

Hz
See Hertz.

Inharmonic
A partial or sinewave component of a sound which bears no simple arithmetic relationship to any other partial in the sound. See also Harmonic.

Microtonality
The exploitation of intervals which lie between the semitone steps of the equal tempered scale. This allows the use of tunings and modes which are more typical of non-western music. This important and underestimated facility is at last becoming available on synthesisers.

MIDI
An agreed standard for communication between electronic musical equipment such as synthesisers, samplers and other devices such as computers. The core function of the standard is to allow information describing musical peformance (which notes were played, how loud they should be, plus articulations such as "bending" of notes or vibrato etc.) to be capable of transmission from one machine to another. The recording of such information for later replay is called sequencing. The standard also includes many functions which are ancillary to this core activity, for example the standardisation of files for sequences (Standard Midi File) and digital audio recordings (Sample Dump Standard) and methods of exchanging information that is unique to individual devices (System Exclusive).

Mode
A simple definition of this complex and diverse term would almost certainly be inaccurate, while a full discussion is beyond the scope of this glossary, but here goes. Essentially a type of scale. If the notes used in a melody all appear in a given modal scale, and if the melody begins or ends on the base note (final) of the modal scale, the melody is said to be in that mode. The modes most commonly referred to can be obtained by playing only (and all of) the white piano notes between certain keys and their octaves thus: Ionian C - C, Dorian D - D, Phrygian E - E, Lydian F - F, Mixolydian G - G, Aeolian A - A. Modes are most commonly encountered in folk and ethnic music. The modern major and minor scales correspond to the ionian and aeolian modes respectively. So it seems that tonal music (most of the music written in the last 300 - 400 years) is based on only two of a number of possible scales, and it is interesting to note that while much European art music has confined itself to a thorough exploration of only these two modes, the rest of the world and European folk musicians have been quietly exploring all the rest and others. In defence of the apparent narrow mindedness of European art musicians, it must be said that the other modes do not easily lend themselves to the systematic and hierarchical structures beloved of them.

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. This resulted in a newer generation of synthesisers which had a more or less predetermined signal path, which were often less flexible but easier to use. There has recently been a revival of interest in modular synthesisers and there are still manufacturers making them.

Monophonic
The ability (or restriction depending on your viewpoint) of an instrument such as a clarinet or some types of synthesiser to play only one note at a time. Generally a monophonic synthesiser will follow a rule to deal with any occasion when two notes appear. It might play the most recently received (remember that in MIDI although you think you play a chord, the notes are sent individually one after the other sufficiently fast (usually) that you think they sound together), or it might play the note with the highest pitch. Some MIDI controllers require synthesisers that can work monophonically across a number of channels, six in the case of a MIDI guitar. Thus although the synthesiser may be polyphonic it is working monophonically on each channel (2). If you think about it a real guitar can be considered to be six monophonic string instruments.

Multistage Envelope Generator
See Envelope Generator.

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.

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

Waveform

Frequency Spectrum
Hear Me (8k)
There are some synthetic types of noise which are useful in sound synthesis and technical equipment alignment etc. These are called white noise, pink noise and (the author has heard) blue noise. White noise contains all frequencies in equal amplitude distribution (and the metaphor is from white light which has a similar attribute). Pink noise is filtered white noise (some frequencies removed) and other colours of the noise rainbow represent other filterings.

Panning
The process of controlling the relative position of a sound in a stereo field during mixdown or recording using a pan-pot. Usually this is not completely effective as the pan-pot alters only the relative amplitude of the sound left to right and not the crucial time aspect.

Partial
(1) A single frequency, sinewave component of any sound. all sounds are composed of a number of partials. There are two classes of partials. See also Harmonic and Inharmonic. (2) Used confusingly by Roland to refer to a basic sound generator in a number of its "LA Synthesis" products, beginning with their MT32.

Perfect Pitch
The ability possessed by some people to describe one or more heard pitches by their note names without error. This is sometimes regarded as a magical ability but is no more remarkable than the ability to name a colour, and like that skill can be learnt by most children and even some adults. It is a rarer skill simply because it is less practised. Some people have a more extreme form where they can not only name the note heard but tell you whether it is flat or sharp. Some even feel discomfort if it incorrect. This "gift" is occasionally described as absolute pitch. It seems to be common among children with autism.

Phon
A unit of apparent sound level or loudness which takes account of the variable human sensitivity to different frequencies.

Pitch
Broadly speaking the musical equivalent of the technical term "frequency", although they are not exactly synonymous. This is usually because pitch is also used as a synonym of note name. So one musician might ask another "What pitch is that?" and be satisfied with the answer "A", whereas the answer "440 Hz" would probably dismay.

Propagation
Movement through a material. e.g. the movement of sound waves through air.

Pulse Wave
A family of geometrical waveforms typically generated by an oscillator.

Waveform

Harmonic Structure
Hear Me (8k)
They are all rectangular in shape, i.e. the only angle which occurs is 90° between immediate, vertical transitions and horizontal "high" or "low" levels, but they have any possible mark/space ratio. Square wave is a special case of pulse wave where the mark/space ratio is 1:2. The harmonic partials present are determined by the mark/space ratio such that the harmonics which are multiples of the rightmost number in the ratio will be absent. Thus a pulse wave with a mark/space ratio of 1:3 will not have the 3rd., 6th. or 9th. etc. harmonics. Other harmonics will be present at varying amplitudes depending on their proximity to the "dead" or absent harmonics. When the ratio becomes very large i.e. the pulse becomes very narrow, the timbre becomes correspondingly thin and nasal, rather like an oboe or harpsichord. See also Ramp Wave, Sine Wave, Square Wave, Triangle Wave.

Ramp Wave
A geometrical waveform typically generated by an oscillator.

Waveform

Harmonic Structure
Hear Me (8k)
It resembles a series of ramps placed nose to tail. It has all possible harmonic partials (odd and even numbered). The amplitude of each harmonic is the reciprocal of its number in the series (i.e. the 5th. harmonic is a 5th. the amplitude of the 1st.) It has a very powerful and brassy timbre. It sounds the same whether the ramp rises left to right or falls left to right. Sometimes called sawtooth. See also See also Pulse Wave, Sine Wave, Square Wave, Triangle Wave.

Reverberation
A complex of many reflected sounds occurring in an enclosed space such as a building or cave. The effect is often confused with echo which, strictly, is a discrete repeat of a sound event. Reverberation occurs to some extent in any place where a sound can occur, but is most noticeable in very large places with many hard reflective surfaces which are at complex angles to one another, such as large churches etc. Most people are able to recognise particular types or reverberation and can associate these with imaginary rooms of varying sizes. Devices for the artificial creation of reverberation ( sometimes called "room simulation") have been available for some time. Initially based on electromechanical devices such as reverb springs or reverb plates, these are now usually digital devices. Several distinct phases are observed in the evolution of a reverberative sound and these include pre delay, early reflections, high & low frequency damping, decay.

Reverberation Time
Also call Rt60. In a reverberant environment, this is the time a sound event will take to decrease in amplitude by 60 dB(SPL). In general bigger spaces will have longer Rt60 times than smaller spaces, however there are a number of other factors to be taken into account such as the damping effect of furniture, curtains or even people.

Sawtooth Wave
See Ramp Wave.

Sine Wave
A geometrical waveform having a curve defined by the function y= sin x.

Waveform

Harmonic Structure
Hear Me (8k)
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. See also See also Pulse Wave, Ramp Wave, Square Wave, Triangle Wave.

Sound Wave
See Wave.

Spectrum
The range of frequencies or partials of an audio signal.

Spectrum Analyser
A device for displaying the relative amplitudes of a range of frequencies or partials in an audio signal.

Square Wave
A geometrical waveform typically generated by an oscillator.

Waveform

Harmonic Structure
Hear Me (8k)
It is a special case of pulse wave, where the mark/space ratio is 1:2. It has only the odd numbered (1, 3, 5, 7, etc.) harmonic partials. The amplitude of each harmonic is the reciprocal of its number in the series (i.e. the 3rd. harmonic is a 3rd. the amplitude of the 1st.). It has a buzzy but mellow timbre very similar to that of a clarinet. See also Pulse Wave, Ramp Wave, Sine Wave, Triangle Wave.

Synthesiser
(1) An electronic device for making sounds, in which the shape and method of construction have little effect on the nature of the sound produced. This wide definition includes: Electronic organs, samplers, drum machines even radio sets etc. as well as those devices which are more immediately recognised as synthesisers. Some devices, such as the Thérémin do owe their sound, in part, to their construction, and may be considered somewhat "grey" in respect of this definition. (2) A specific case of (1) above, equipped with oscillators, filters, amplifiers as well as modulation sources. Either with a predetermined or more or less programmable audio and control signal path, which can be used as a musical instrument or for sound effects. The oscillators may include the ability to replay digital recordings of sounds, and the whole or part of the system may be implemented using digital or analogue technologies.

Timbre
The quality of a sound determined by its partial structure, that is the relative frequencies and amplitudes of the various sinewaves 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 a flute and an oboe playing the same pitch at the same volume.

Triangle Wave
A geometrical waveform typically generated by an oscillator.

Waveform

Harmonic Structure
Hear Me (8k)
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.

Wave Waveform
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.

White Noise
A signal which contains all possible audio frequencies in equal average amplitudes. Useful for testing equipment.

http://www.musonix.co.uk/books-smj.htm Godric Wilkie