A.D.S.R
Acronym for Attack, Decay, Sustain, Release.
AES
Acronym of the Audio Engineering Society
Aliasing
A type of distortion that occurs when digitally recording high frequencies with a low sample rate. For example, in a motion
picture, when a car's wheels appear to slowly spin backward while the car is quickly moving forward, you are seeing the effects
of aliasing. Similarly when you try to record a frequency greater than one half of the sampling rate (the Nyquist Frequency),
instead of hearing a high pitch, you may hear a low-frequency rumble.
Alpha Channel
Alpha is a fourth channel that determines how transparency is handled in an image file. The RGB channels are blended to determine
each pixel's color, and the corresponding alpha channel determines each pixel's transparency. The alpha channel can have up to 256
shades of gray: 0 represents a transparent pixel, 255 represents an opaque pixel, and intermediate values are semitransparent.
Amplitude
The level of a signal - often regarded as being the volume or loudness of a signal.
Analog
When discussing audio, this term refers to a method of reproducing a sound wave with voltage fluctuations that are analogous to
the pressure fluctuations of the sound wave. This is different from digital recording in that these fluctuations are infinitely
varying rather than discrete changes at sample time.
ASIO
Acronym of Audio Streaming Input / Output, an audio driver format introduced
by Steinberg to accomodate low-latency routing between audio hardware and ASIO-compatible
software.
Attack
In music, it is the period between the note being struck,
and its peak in terms of sound pressure level (the time taken for a
sound to achieve maximum amplitude). It could be described as being a sounds
initial transient.
Attenuate
To make lower in level.
Aux
Control on a mixing desk designed to route a proportion of a channel signal
to the effects or cue mix outputs.
Back-up
Safety copy of software or other digital data - songs, work files etc.
Personal recommendation is to use chronological nomenclature with regards to
working files.
For example, "essential mix_01", next save "essential mix_02" etc. This means you can always
revert back to a previous version if you decide you do not like recent decisions.
Balanced
An audio convention, most commonly a three pin "XLR" type mic cable, which
has two conduction channels surrounded by shielding. The conductors should have equal
potential (akin to signal amplitude) 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 "phase cancellation".
Bandwidth
When discussing audio equalization, each frequency band has a width associated with it that determines the range of frequencies that
are affected by the EQ. An EQ band with a wide bandwidth will affect a wider range of frequencies than one with a narrow bandwidth.
When discussing network connections, refers to the rate of signals transmitted; the amount of data that can be transmitted in a fixed
amount of time (stated in bits/second): a 56 Kbps network connection is capable of receiving 56,000 bits of data per second.
Band Pass Filter
A filter which allows only certain audio frequencies to pass, while rejecting
all others above and below the cutoff points.
Bi Directional Microphone
Microphone that will pick up sounds which are emanating from the front of the
microphone (on-axis), and the rear of the microphone (off-axis), and largely reject those to
the side. Also described as a "figure of eight" microphone.
Binary
Counting system based on a series of only 2 numbers - "0" and "1". All
digital data is comprised of binary.
Bit
A bit is the most elementary unit in digital systems. Its value can only be 1 or 0, corresponding to a voltage in an electronic
circuit. Bits are used to represent values in the binary numbering system. As an example, the 8-bit binary number 01111111
represents the unsigned value of 127 in the decimal system. In digital sampling, a binary number is used to store individual
sound levels, called samples
Bit Depth
The number of bits used to represent a single sample. Vegas software uses either 8, 16 or 24-bit samples. Higher values will increase
the quality of the playback and any recordings that you make. While 8-bit samples take up less memory (and hard disk space), they
are inherently noisier than 16 or 24-bit samples.
Bouncing
Process of mixing two or more recorded tracks together and re-recording these
onto another track.
BPM
Acronym for Beats per minute. A guide to the tempo of a piece of music.
Brightness
Adjusting brightness adds or subtracts values from the color channels in an image to make the image lighter or darker. The
maximum brightness setting adds 255 (pure white), and the minimum setting adds 0 (pure black). These numbers are based on the computer
RGB color space.
Brown Noise
The brown note, according to an urban legend, is an infrasound frequency that causes humans to lose control of their bowels due
to resonance. There is no scientific evidence to support the claim that a "brown note" (transmitted through sound waves in air) exists.
Buffer (especially computer audio)
A temporary storage location in memory, where data is stored until it is
ready for processing - it is also linked to latency.
Bus
A virtual pathway where signals from tracks and effects are mixed. A bus's output is a physical audio device in the computer where
the signal is routed. The configuration of busses is saved with the project whereas the routing of busses to hardware is saved with
the system. In this way, projects can be easily moved from one system to another without modifying the original layout of the project.
Byte
Refers to a set of 8 bits. An 8-bit sample requires one byte of memory to store, while a 16-bit sample takes two bytes of memory to store.
CCD
Charge coupled device - the sensor (image) in a digital camera / camcorder.
Cent
A musical cent is one hundredth of a semitone.
Chorus
Chorus: - Signal processing which creates an electronic simulation of a
chorus by combining a signal with a delayed copy of itself. Often, the delay time and level
of the copy is continuously varied in the interests of added "reality". This part of the
process is known as flanging, often used as an effect in itself.
Chroma
The values that convey chrominance information (color information).
Chromatic
Describes a scale of pitches rising in steps of one semitone.
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.
Codec
COder / DECoder - method used for compression of data. Can be lossless or lossy. An example of a codec is DivX.
Compressor
A device designed to reduce the dynamic range of audio signals by reducing
the level of high signals or by increasing the level of low signals.
Console
Alternative term for a mixer / mixing desk.
CPU
Central Processing unit
Cross-Over
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.
Crossfade
Mixing two pieces of media by fading one out as the other fades in.
Cut-off Frequency
Frequency above or below which attenuation begins in a filter circuit.
Daisy Chain
Term used to describe serial electrical connection between devices or
modules.
DAT
Acronym of Digital Audio Tape. A magnetic tape which is used to record a
signal digitally.
dB
Abbreviation of Decibel. A unit which is used to express the relative levels
of two electrical voltage, powers or sounds.
DC Offset
DC Offset occurs when hardware, such as a sound card, adds DC current to a recorded audio signal. This current causes the
audio signal to alternate around a point above or below the normal -infinity dB (center) line in the sound file. To visually
see if you have a DC offset present, you can zoom all the way into a sound file and see if it appears to be floating over the center line.
Decay
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 remains at this level until the trigger
is released, at which point the release phase is entered.
De-esser
A device for reducing the effect of siblance in vocal signals.
Dithering
System of adding low-level noise to a digitised audio signal in such a way as
to extend low-level resolution at the expense of a slight increase in overall noise level. This technique is used to hide quantization noise.
Dry
Signal to which no effects have been added. The opposite of this is wet
.
Ducking
Method of controlling one audio signal with another. For example, background
music can be made to duck whenever there is a voice-over.
Dynamic Range
Range in decibels between the highest signal that can be handled by a piece
of equipment and the level at which small signals disappear into the noise floor.
Dynamics
Method of describing the relative levels within a piece of music.
Effects Loop
Connection system that allows an external signal processor to be connected
into the audio chain.
Effects Return
Additional mixer input designed to accomodate the output from an effects
unit.
Enhancer
A device designed to brighten audio material using techniques such as
dynamics, equalisation, phase shifting and harmonic generation.
Equaliser
A device for selectively cutting or boosting selected parts of the audio
spectrum.
Exciter
Enhancer that works by synthesising new high-frequency harmonics.
Expander
A device 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.
Expander Module
Synthesiser with no keyboard, often rack mountable, or in some other compact
form.
Feedback
In short, it is the picking up of audio via a microphone that is then played
out the speakers, and then picked up by the microphone, then played out the speakers...Etc.
This happens several hundred or thousand times in a second, creating a sharp high pitched
tone, or low frequencies, or anything between. An issue that must be accounted for in all
live sound situations.
In a circuit - feedback can occur when the input is mapped to its output -
creating a loop.
Flanger
Short, pitch-modulated delay with feedback that, when added to the original
signal, produces a deep comb-filtering effect reminiscent of tape-phasing. An effect
certainly popular with guitarists...
FPS
Frames Per Second. See frame rate
Frame Rate
The speed at which individual images in the video are displayed on the screen during playback. A faster frame rate
results in smoother motion in the video. The television frame rate in the US (NTSC) is 29.97 frames per second (fps).
In many parts of Europe and Japan, the television standard is PAL at 25 fps.
Frequency
Indication of how many cycles of a repetitive waveform occur in one second.
A waveform that has a repitition cycle of once per second has a frequency of 1 Hz.
Frequency Response
Measurement of the frequency range that can be handled by a specific piece of
electrical equipment, or loudspeaker.
Frequency Spectrum
The Frequency Spectrum of a signal refers to its range of frequencies. In audio, the frequency range is basically 20 Hz
to 20,000 Hz. The frequency spectrum sometimes refers to the distribution of these frequencies. For example, bass-heavy sounds
have a large frequency content in the low end (20 Hz - 200 Hz) of the spectrum.
Fundamental
Any sound comprises a fundamental of basic frequency plus harmonics and
partials at ahigher frequency.
FX
Abbreviation of effects.
Gain
Amount by which a circuit amplifies a signal.
Gamma
Determines the brightness of the video and is used to compensate for differences between the source and output video and sometimes
needs to be calibrated to match the source or destination. Higher gamma values result in lighter or brighter video as displayed
on your computer's monitor.
Gamut
Gamut refers to the complete range of something. In video editing, you want to ensure that your colors are within the
acceptable range for your broadcast standard. When colors are outside the NTSC or PAL gamut, you can introduce image problems or
noise into the video stream.
Gate
A device designed to mute low-level signals, thus improving the noise
performance during pauses in the wanted material.
General MIDI
see MIDI.
Graphic Equaliser
Equaliser on which several narrow segments of the audio spectrum are
controlled by individual cut / boost faders. The name derives from the fact that the fader
positions provide a graphic representation of the EQ curve.
Group
Collection of signals within a mixer that are mixed and then routed through a
seperate fader to provide overall control. A useful working example, is when you have the
levels of a whole drumkit set up over several faders, and you want to adjust the level of the
entire kit easily.
By grouping them together, you can simply control the overal level with a single fader, as
opposed to trying to move several faders the same amount to maintain your 'perfect' mix.
GS MIDI
See MIDI.
Harmonic
High-frequency component of a complex waveform.
Harmonic Distortion
Addition of harmonics not present in the original signal.
Headroom
Safety margin in decibels between the highest peak signal being passed by a
piece of equipment and the absolute maximum level the equipment can handle.
Hertz
Unit of measurement for frequency or cycles per second. Abbreviated to Hz
High Pass, Low Pass, Band Pass
A high pass filter enables the passage of higher frequencies, and stops the
passage of lower frequency signals. Conversely, a low pass filter allows the passage of low
frequency signals, whilst blocking the higher frequency signals. A band pass filter,
is the rolling of frequencies both above and below the appropriate roll-off frequencies,
(similar to both low and high pass filter together) and useful for mid-range frequencies.
Hiss
Noise caused by random electrical fluctuations.
Hum
Signal contamination caused by the addition of low frequencies, usually
related to the mains power frequency.
Hz
Abbreviation of Hertz, the unit of frequency.
Infrasonic
Sound frequencies which are below the lowest frequency of human hearing (20
Hz)
Interface
An intermediary to two or more pieces of equipment. For example, a MIDI
interface enables a
computer to communicate with MIDI instruments and keyboards.
Inverse Telecine
Telecine is the process of converting 24 fps (cinema) source to 30 fps video (television) by adding pulldown fields.
Inverse telecine, then, is the process of converting 30 fps (television) video to 24 fps (cinema) by removing pulldown.
IPS
Acronym of Inches Per Second, a measurement of the speed that a tape travels
when it is playing
ISRC Code
Industry Standard Recording Codes (ISRC) were designed to identify CD tracks.
The ISRC code is a 12-character alphanumeric sequence in the following format:
AA|BBB|CC|DDD|EE where A depits country of origin, B depicts first owner, C represents yars of recording, D is recordings serial number
and E is the recording item, which for example identifies tracks on a CD.
Jack Plug
Popular form of audio connector, available in stereo or mono formats.
A full sized Jack plug has a spur of a quarter of an inch (6.25mm), but there are also
smaller "mini" jack plugs - typically 3.5mm. This shape of connector is also identical to
a TRS connector.
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 explaination), leading to amplitude (signal level) errors.
The distortion is more pronounced at the higher end of the frequency spectrum. Jitter
also refers to timing errors where the word clock is an embedded part of the datastream
(self-clocking).
k / Kilo
Abbreviation of 1,000. Used as a prefix to other values to indicate
magnitude. For example, 10,000Hz can be expressed as 10kHz.
Latency
Delay between the time audio enters an audio system, and the time it becomes
audible at the
output. Latency is caused by the need to route audio via a CPU, where buffers are used to
ensure a constant stream of audio data. ASIO drivers minimise latency, but it can never be
completely eradicated. If latency is below 7ms, it isn't considered to be a problem.
Personal experience has shown me the following typical values. "Multimedia
drivers" in
a computer system - approx 750ms. "DirectX drivers" approx 40ms. Semi-pro equipment and
appropriate drivers approx 7ms. Professional equipment and appropriate drivers approx 2ms.
As an extra, you can get 0 latency monitoring solutions depending on manufacturer.
LFO
Acronym for Low Frequency Oscillator.
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 the protection of ears loudspeakers etc.
Line level
Mixers and signal processors tend to work at a standard signal level known as
line level. In practice there are several different standard line levels, but all are in a
similar range. A nominal signal level is around -10dBv for semi-pro equipment and +4dBv for
professional equipment.
Low Pass Filter
Filter that attenuates those frequencies that occur above its cut-off
frequency.
LSB
Abbreviation of Least Significant Byte. If a piece of data has to be
conveyed as two bytes, one byte represents high-value numbers and the other low-value numbers,
in much the same way as tens and units function in the decimal system. The high value, or
most significant part of the message, is called the most signicant byte, or MSB.
Luma
Conveys Lumincance information - which is the brightness of an image, without respect to its color content (chroma).
Master
A device which controls another device, known as the slave. The final mix of
a piece of music.
m / meg
Abbreviation of 1,000,000. For example 1,000,000Hz can be written 1MHz.
Mic Level
Low-level signal generated by a microphone. This must be amplified many
times to increase it to line leve.
MIDI
Acronym for Musical Instrument Digital Interface.
"General" MIDI (GM): - Standard set of sounds for use within MIDI system
(MIDI keyboards, MIDI compatable soundcards etc) which are designed to ensure compatibility
for the playback of MIDI files. A sound set of 128 sounds is the standard.
"GS MIDI": - An extension to the General MIDI system (see above) created by
the Roland corporation. Improvements over the standard GM include reverb / chorus effects,
panning controls, and the capability of expanding the standard GM set of 128 sounds up to a
maximum of over 16,000!
MIDI Clock
A MIDI device specific timing reference. It is not absolute time like MTC, instead it is a tempo dependent number of "ticks"
per quarter note. MIDI Clock is convenient for synching devices that need to do tempo changes mid-song.
MIDI Time Code (MTC)
MTC is an addendum to the MIDI 1.0 Specification and provides a way to specify absolute time for synchronizing MIDI capable applications.
Basically, it is a MIDI representation of SMPTE timecode.
"XG (MIDI)" : - An extension to the General MIDI system (see above) similar the
Roland "GS" system with extra sounds, effects etc, only this system was developed by Yamaha,
rather than Roland.
Mixer
A device for combining two or more audio signals.
Monitor
Reference loudspeaker used for mixing. Unlike normal HI-FI speakers,
monitors are designed to have a flat frequency response - so that they do not 'colour' the
sound of the mix.
Monitoring
The process of listening to a mix or a specific audio signal.
Monophonic
Relates to a Synthesiser (or other instrument) which is only capable of
playing one note at a time. See also polyphonic.
MTC
Acronym for MIDI Time Code. This is a MIDI sync implementation based on
SMPTE code.
Multi-timbral
Capability for an electronic instrument to play more than one sound / patch
at the same time.
Multi-tracking
Ability to record and process several separate streams or "tracks" of audio,
either together
or at different times, to be played back as a synchronous whole, then probably "mixed down"
to a stereo (two track) master for replay on ordinary systems.
Multiple Stereo
A mixer configuration that allows you to assign individual tracks to any number of stereo output busses. In single stereo
mode, all tracks go out the same stereo bus. Multiple stereo configuration allows you to keep your signals from the tracks
discrete if you want them to be.
Noise Floor
Amount of background noise produced by a piece of audio hardware, measured
in dB's.
Noise Shaping
System for creating digital dither so that any added noise is shifted into those parts of the audio spectrum where the human
ear is less sensitive. For example, in 44,100 Hz audio quantization noise is shifted towards the Nyquist Frequency of 22,050 Hz.
Nondestructive Editing
This type of editing involves a pointer-based system of keeping track of edits. When you delete a section of audio in a
nondestructive system, the audio on disk is not actually deleted. Instead, a set of pointers is established to tell the program
to skip the deleted section during playback.
Normalisation
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.
Nyquist Theorem / Frequency
Theorem which deals with the digital audio problem of "Aliasing". The Nyquist
theorem proves that the highest frequency recordable through digital sampling technology
(without the horrible distortion caused by aliasing) will be half that of the sampling rate
used. In practice, the sampling rate used should be @10% more than double. This is due to the
fact that the Anti Aliasing filters used in the Analogue to Digital conversion process,
despite having a very sharp roll off, do not reach their 0dB cutoff points until they are @10%
higher also.
An example of this is the "Red Book" standard which governs the production of
nearly all audio CD's. Here, in order to record "full frequency" audio up to 20 kHz the
specified sampling rate is 44.1 kHz, this allows for the problem that the anti aliasing
filters will have started rolling off at 20khz, finally reaching their cut off point @
22.05kHz.
Octave
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 eg
if A4 has a frequency of 440 Hz, then A5 (an octave above) will have a frequency of 880 Hz.
Oscillator
Circuit designed to generate a periodic electrical waveform.
Overdub
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 Multitrack Recording.
Overload
To exceed the operating capacity of an electronic or electrical circuit.
Pad
Resistive circuit for reducing signal level.
Pan pot
Control enabling the user of a mixer to move the signal to any point in the
stereo soundstage by varying the relative levels fed to the left and right outputs.
Parametric EQ
Equaliser with seperate controls for frequency, bandwidth and cut / boost.
Patch Bay
System of panel-mounted connectors used to bring inputs and outputs to a
central point from
where they can be routed using plug-in cords. It enables easy re-wiring of equipment from a
single and easily accessible area.
Patch Cable
Short cable uses with patch bays.
Peak
Maximum instanteneous level of a signal.
Highest signal level occuring in any section of material.
PFL
Acronym for Pre Fader Listen. A system used within a mixing console that
allows the operator to listen in on selected signals, 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
Timing difference between two electrical waveforms expressed in degree, where
360degrees corresponds to a delay of one cycle.
Phaser
Effect that combinesa signal with a phase-shifted version of itself to
produce a creative filtering effect. Most phasers are controlled by means of an LFO.
Phono plug
Hi-fi connector developed by RCA and used extensively on semi-pro, unbalanced
equipment. Note that its design means it can never be used for balanced purposes.
Pink Noise
Pink noise is a signal or process with a frequency spectrum such that the power spectral density is proportional to the reciprocal
of the frequency (1/f).
Pitch
Musical interpretation of an audio interface.
Pitch Shifter
A device for changing the pitch of an audio signal without changing its
duration.
Plug-In
An effect that can be added to the product to enhance the feature set.
Plug-In Chain
Plug-ins can stringed together into a chain so that the output of one effect feeds into the input of another.
This allows for complex effects that could not otherwise be created
Polyphonic
Ability for musical device (keyboard etc) to play more than one note at the
same time. If an instrument is say, 64 note polyphonic, it has the ability to play up to 64
notes at the same time.
Portamento
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.
Post Production
Work that is carried out on a recording once 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.
Post-Roll
Post-roll is the amount of time after the event. The time selection defines the pre- and post-roll when
recording into a selected event.
Pre-Fade
Aux signal taken from before the channel fader so that the channel fader has
no effect on the aux send level. Normally used for creating foldback or cue mixes.
Pre-Roll
Pre-roll is the amount of time elapsed before an event occurs. The time selection defines the pre- and post-roll when
recording into a selected event.
Pulse Code Modulation (PCM)
PCM is the most common representation of uncompressed audio signals. This method of coding yields the highest
fidelity possible when using digital storage.
Punch-In
Method of making a device automatically start recording once a certain point
in the track has been reached. Especially useful for those trying to record themselves.
Often involves the use of a marker, or similar reference point.
Punch-Out
Method of causing a device to end recording, but generally continue playing,
automatically.
Q
Measurement 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.
Also used with regard to EQ - where Q represent the width / bandwith of the EQ filter. For
example, the Q value could be 1 octave, or 3 octaves.
Quadraphonic
A mixing implementation that allows for four discrete audio channels. These are usually routed to two front speakers
and two back speakers to create immersive audio mixes.
Quantize
Sequencers ability to make notes / beats recorded conform to the nearest
subdivision of a bar. These subdivisions may be predetermined by the user (e.g. 1/64, 1/16
etc). A useful tool in the correction of timing errors, however overuse may result in the
performance having a somewhat "robotic" feel.
Quantization
The process by which measurements are rounded to discrete values. Specifically with respect to audio,
quantization is a function of the analog to digital conversion process. The continuous variation of the voltages of a
analog audio signal are quantized to discrete amplitude values represented by digital, binary numbers. The number of
bits available to describe these values determines the resolution or accuracy of quantization. For example, if you
have 8-bit analog to digital converters, the varying analog voltage must be quantized to 1 of 256 discrete values;
a 16-bit converter has 65,536 values.
Quantization Noise
A result of describing an analog signal in discrete digital terms (see quantization). This noise is most easily heard
in low resolution digital sounds that have low bit depths and is similar to a "shhhhh" type sound while the audio is playing.
It becomes more apparent when the signal is at low levels, such as when doing a fade out.
Real time
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.
Red Book standard
Standard set by the Phillips and Sony corporations which governs the audio
standard for virtually all audio CD production. Instituted to ensure compatabilty between CD's
and their players, it states that audio should be of a standard which is 16 bit,
uncompressed and recorded with a sample rate 44.1 kHz per second. On a computer, audio files
recorded at these rates are usually known as "WAV" files.
The Red Book defines the specifications for every audio compact disc throughout the world. Red Book specifications
define not only the information within the disc (digital audio recorded at 44.1 kHz), but also the disc size and the way
in which the audio is arranged. It is the Red Book standard — the foundation upon which all other CD standards are built — that
enables all audio compact discs to play in all audio compact disc players or drives. It is this interchangeability that has
fueled the rapid growth of the CD music industry.
Release
Time it takes for a level or gain to return to normal. Often used to
describe the rate at which a synthesised sound reduces in level after a key has been released.
Resample
The act of recalculating 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 points are removed from the sound file decreasing its size, but also
decreasing its available frequency range. When resampling to a higher sample rate, extra sample points in the sound file
are interpolated. This increases the size of the sound file but does not increase the quality. When down-sampling one
must be aware of aliasing.
Resolution
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.
Resonance
Characteristic of a filter that allows it to selectively pass a narrow range
of frequencies.
The term used to describe the natural frequency of an object - in which when
the object is subjected to such a frequency, the object will vibrate in harmony.
Reverberation
Gradual decay of a sound due to multiple echos reflecting from the many
surfaces of an acoustic environment.
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 signals but instead comprises new
frequencies based on the sum and difference of the input signals' frequency components. The
results may be either musical or extremely dissonant, depending on the relationships between
the input signals. For example, ring modulation can be used to create bell-like tones.
Sample
The word sample is used in many different ways when talking about digital sound. For example:
A discrete point in time that a sound signal is divided into when digitizing. An audio CD-ROM contains 44,100 samples per second.
Each sample is really only a number that contains the amplitude value of a waveform measured over time.
A sound that has been recorded in a digital format; used by musicians who make short recordings of musical instruments to be
used for composition and performance of music or sound effects.
Sampling Rate
Number of times that an A / D converter samples the incoming waveform each
second. There are a few standards within the industry. The common CD standard,Red Book
specifies 44,100Hz. Professional equipment tends to be 48,000Hz. Modern equipment is
showing a tendancy towards 96,000Hz, and some manufacturers offer the ability of 192kHz.
Storage requirements increase vastly as higher rates are used.
Sampler
Device which has the ability to record sounds digitally, then assign a
musical pitch value to that sound so that it may played as musical notes on a compatible
instrument (usually a keyboard).
Shock Mount
Device for holding a microphone, which is designed to provide shock
absorbtion / insulation from any vibrations which may be transmitted through a microphone
stand. Usually used with particularly sensitive condenser microphones.
Sibilance
High-frequency whistling or lisping sound that affects vocal recordings due
either to poor mic technique, or excessive equillisation.
Side Chain
Part of a circuit that splits off a proportion of the main signal to be
processed in some way.
Compressors use a side-chain signal to derive their control signals.
Signal Chain
Path taken by a signal. This can either be from the input to the output of
one device, or the path taken through many different devices (eg from microphone to mixing
desk / signal processing devices then amplifier(s), speakers etc).
Signal to Noise ratio
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.
Slave
SMPTE
Time code developed for the film industry but now extensively used in music
and recording. SMPTE is a real-time code and is related to hours, minutes, seconds and film or
video frames rather than to musical tempo. SMPTE stands for the Society of Motion Picture and
Television Engineers.
SPL
Acronym for Sound Pressure Level, measured in decibels.
A device which is controlled by another device, which is referred to as the
master.
Stereo
Two-channel system feeding left and right loudspeakers.
Sub-Bass
Bass frequencies which are below the point where sound is directional (@
150Hertz) and above the point where it can no longer be heard (@20 Hertz). below this, it is
known as "infra bass".
It is the fact that sound is not directional below 150 Hz (you dont need a stereo pair to
recreate its position in space) which enable the design of loudspeaker systems with solitary
sub bass units which may be tucked away behind sofa's etc!
Subcode
Hidden data within the CD and DAT format that includes such information as
the absolute time location, number of tracks, total running time etc.
Surround
5.1 surround is a mixer implementation that includes six discrete channels
Sustain
Part of the ADSR envelope that 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.
Refers to the ability of an instrument, such as guitar, to hold notes that
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.
Sync
System for making two or more pieces of equipment run in synchronisation with
each other.
Telecine
The process of creating 30 fps video (television) from 24 fps film (cinema).
Tempo
Rate of the beat of a piece of music, measured in BPM.
Test Tone
Steady, fixed-level tone recorded onto a multitrack or stereo recording to
act as a reference when matching levels.
THD
Acronym of Total Harmonic Distortion.
Timbre
The harmonic qualities of a sound. Tonal 'colour' of a sound.
Track
A discrete timeline for audio data. Audio events sit on audio tracks and determine when a sound starts and stops.
Multiple audio tracks are mixed together to give you a composite sound that you hear through your speakers.
Transpose
To shift a musical signal by a fixed number of semitones.
Tremolo
Modulation of the amplitude of a sound using an LFO. Often incorrectly used
to describe a variance, or 'wobble' in pitch - especially with regards to guitars (even the
manufacturers call the 'whammy bar' a tremolo bar - although this trend is dying slowly).
Trim
Controls the level of input on a mixing desk.
TRS jack
Stereo-type jack with tip, ring and sleeve connections.
µ-Law
µ-Law (mu-Law) is a companded compression algorithm for voice signals defined by the Geneva Recommendations (G.711).
The G.711 recommendation defines µ-Law as a method of encoding 16-bit PCM signals into a non-linear 8-bit format. The algorithm is
commonly used in European and Asian telecommunications. µ-Law is very similar to A-Law, however, each uses a slightly
different coder and decoder.
Ultrasonic
Sound frequencies which are above the highest frequency of human hearing (20
kHz). See also Infrasonic.
Unison
To play the same melody using two or more different instruments or voices.
Unity gain
The term given to devices that are set to '0' - meaning that the device is
neither amplifying or attenuating signal level.
Velocity
Rate at which a key is depressed. This may be used to control loudness (to
simulate the response of instruments such as pianos) or other parameters on later
synthesisers.
Vibrato
Pitch modulation using an LFO. The correct term for gentle pitch bending on
instruments such as guitars (technically the fretting finger acts as a LFO).
Virtual MIDI Router
A software-only router for MIDI data between programs. No MIDI hardware or cables are required for VMR, so routing can only be
performed between programs running on the same PC.
Vocoder
Signal process that imposes a changing spectral 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.
Voice
Capacity of a synthesiser to play a single musical note. An instrument capable of playing 16
simultaneous notes is said to be a 16-voice instrument.
VST
Acronym of Virtual Studio Technology, a Steinberg (think Cubase...) protocol
that allows a common range of plug-in effects and instruments to be used with VST-compatible
host software.
Wah-wah pedal
Guitar effect device in which a bandpass filter is varied in frequency by
means of a pedal control.
Warmth
Subjective term used to describe sound in which the bass and low-mid
frequencies have depth
and the high frequencies are smooth sounding, rather than aggressive or fatiguing.
WAV
"Windows" Digital file format which is usually 16bit (although it can be 8)
and mostly uses a sample rate of 44.1 kHz (although this too may vary).
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
Graphical representation of the way in which a sound wave or electrical wave
varies with time.
Wet signal
A signal which has been processed in some way (by reverb, eq, or whatever).
Opposite of "dry" signal.
White Noise
Random signal with an energy distribution that produces the same amount of
noise power per Hz. Other noise patterns include Pink Noise and Brown Noise.
Wow and Flutter
More from the old days of tape machines, turntables etc than the modern,
"digital" age. 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.
XG
See MIDI.
XLR
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 / outputs.
Another definition is "Ground Live Return" (in electrical schematics the
ground signal can be represented with an "X"). As part of a balanced line, you have a send /
live and the return.
Y Connector
Where two connectors are fed into one connector of the same type, enabling a
signal path to be split into two.
Yellow Book standard
Originally devloped by the Phillips and Sony corporations, and similar to the
"Red Book" standard (see above). However it is slightly less strigent, in order to accomodate
the CD ROM drives found in most Personal Computers.
Zero level
The level of 0dBV. This is NOT the lowest level, but rather, it is (usually)
the optimum level for recording and broadcast purposes, getting the best signal to noise ratio
without "going into the red", and the distortion that entails. See also Unity Gain.
Zero Crossing Point
Both sounds and electrical signals are primarily oscillations, and they
oscillate around around an equilibrium or axis known as the "zero crossing point", where a
negative signal crosses over into being a positive signal, or vice versa. It is also sometimes
referred to as the "null point".
In recording / sampling / loops etc, the start and end points of an edit
should conform to the zero crossing point of the signal, in order to avoid irritating "clicks"
which are the result of two conflicting signal amplitudes (level of signal).
Zipper Noise
Audible steps that occur when a parameter is being varied in a digital audio
processor.
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