The Digital Audio Vocabulary
There is little doubt that the world of digital audio can be intimidating to
newcomers. With that in mind, we thought it would be helpful to have an index of
terms and ideas to refer to during your journey into the digital realm. This is by no
means a one stop reference for all your digital audio questions, but we believe a
good jumping off point that will encourage your own self discovery. Immediately
following this index you will find a list of links that we find helpful and informative
regarding digital audio and themes discussed in this presentation.
A to D Conversion/Converter - Analogue to Digital conversion. A
converter is a piece of circuitry that achieves this. The quality of conversion
is highly dependent on the amount of bits used in the conversion process,
hence a 24 bit converter will achieve a much more accurate reproduction of
the sound than say, an 8 bit converter.
Analog (or analogue) recording - A technique used to store signals of
audio or video information for later playback. Analog recording methods
store audio signals as a continual wave in or on the media. The wave might be
stored as a physical texture on a phonograph record, or as a change in the
field strength of a magnetic recording. This is different from digital recording,
which converts audio signals into discrete numbers (1’s and 0’s).
Digital The use of Binary data to represent information, "Binary" meaning
that the highly complex data (audio, video, whatever) has been broken down
into many values which have one of two states, positive and non positive.
(Positive is represented by 1, and non-positive by 0) Each value is known as
DAW (Digital Audio Workstation) - A computer-based DAW has three
components: a computer, an Audio to Digital Converter, Digital to Audio
Converter, and digital audio editor. The computer acts as a host for the sound
card and software and provides processing power for audio editing. The
sound card acts as an audio interface, typically converting analog audio
signals into digital form, and for playback converting digital to analog audio;
it may also assist in further processing the audio. Most computer-based
DAWs have extensive MIDI recording, editing, and playback capabilities.
DSP (Digital Signal Processing) - Uses mathematics to change a digital
signal (such as a digital audio stream) in a way that fundamentally changes
the original sound. DSP is used heavily in software and hardware effects
processing. DSP chips are found on an increasing number of Sound Cards to
provide extra audio processing power and help relieve the computers CPU of
this type of work, much like a 3D graphics accelerator would for rendering
Envelope - The intensity of a sound is generally not a static quantity, but
changes over the duration of the sound. This change in the intensity of a
sound over time is called an envelope.
Frequency - The rate per second at which an oscillating body vibrates.
Usually measured in Hertz (Hz), humans can hear sounds whose frequencies
are in the range 20 Hz to 20kHz.
Gain - The level of amplification of a given signal. Sound professionals tend
to use this term where the layman may say "volume".
Latency - A short period of delay (usually measured in milliseconds)
between when an audio signal (sound) enters and when it emerges from a
system. Potential contributors to latency in an audio system include analog-
to-digital conversion, buffering, digital signal processing, transmission time,
digital-to-analog conversion and speed of sound.
Loop - At it’s most basic, a loop is a series of instructions (computing) or
beats/notes/chords (music) that is capable of constant repetition,
consistently having the same result. Musically this will usually be a short
piece measured in terms of a bar or more, which will seamlessly repeat
without any musical or tempo inconsistencies, annoying clicks, etc. due to
MIDI (Musical Instrument Digital Interface) - An industry-standard
protocol that enables electronic musical instruments (synthesizers, drum
machines), computers and other electronic equipment (MIDI controllers,
sound cards, samplers) to communicate and synchronize with each other.
Unlike analog devices, MIDI does not transmit an audio signal— it sends
event messages about pitch and intensity, control signals for parameters
such as volume, vibrato and panning, cues, and clock signals to set tempo. As
an electronic protocol, it is notable for its widespread adoption throughout
the music industry. Most MIDI keyboards and controllers are USB and
therefore take little to no setup to get them to work. They are "plug and
play" meaning the software should recognize its presence. USB is also hot
swappable, which means that in most cases a USB device can be plugged in
and unplugged without restarting the computer.
MIDI IN - Receives MIDI information from another device.
MIDI OUT - Transmits MIDI information to another device.
MIDI THRU - Allows data to pass through unaltered, which enables many
instruments to be connected in series.
(MIDI) Controller - A device, such as a keyboard, that transmits a midi
message to the computer and intern triggers a sound or note or control
(MIDI) Interface - A hardware interface that is either inserted into one of
the computer's internal expansion slots or plugged into a computer USB port.
It allows the computer to communicate with other MIDI instruments by
adding one or more MIDI input and output ports.
Mixer - A hardware or software device that combines multiple audio signals
into one destination signal. Mixers usually provide control over the volume
and/or stereo balance of each source signal.
Noise - In audio, recording, and broadcast systems audio noise refers to the
residual low-level sound (usually hiss and hum) that is heard in quiet periods
Patch - Refers to an instrument sound, program or setting on a synthesizer,
sampler or software program. This term comes from the roots of hardware
synthesis, where physical cables where used to connect and route signals to
create a unique sound (same concept as phone operators "patching" a call
Plug-In - A "client program" that is used to expand the functionality of a
"host program", such as a sequencer or digital audio editor. The host
provides the plug-in with some type of input data such as digital audio
samples, which is then processed to generate new output, such as effected
digital audio. A plug-in is often run seamlessly from within a host program
appearing to be part of the standard interface, a single plug-in can be used by
multiple host programs that share the same plug-in format. Two popular
plug-in formats used in computer music and audio are DirectX Plugin and
VST Plugin digital audio plug-ins. Apple also uses AU (Audio Unit) plug-ins.
These are Apple specific and work within the Core Audio of Mac OSX.
Quantize - Sequencers ability to make notes or beats recorded conform to
the nearest subdivision of a bar. Subdivisions can be predetermined by the
user in increments such as 1/64, 1/16, 1/8 etc. A useful tool in the
correction of timing errors. However, overuse may result in the performance
having a somewhat "robotic" feel.
Sample - A sound or short piece of audio stored digitally in a computer,
synthesizer or sampler. A complete sound or digital audio stream made up of
a collection of individual samples.
Sequencer - A hardware device, software application or module used to
arrange (i.e. sequence) timed events into some order. In digital audio and
music, sequencers are used to record and arrange MIDI and/or audio events
into patterns and musical compositions.
Signal - In electronics/audio, a signal is a transmission of an electrical value
through a conductive medium. In music, this can either be an electronic
representation of an acoustic sound (piano, vocals, guitar etc.), or a sound
that has been originally generated though electronic means (synthesizer).
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.
(For example; Guitar -> Delay Pedal -> Mixing Board -> Speakers)
Sound Card - A hardware interface that is either built into a computer's
motherboard or inserted into one of the computer's internal expansion slots.
Sound cards allow the computer to play digital audio and/or musical
instrument sounds. Many sound cards also provide a MIDI Interface.
Universal Serial Bus (USB) - A connection that establishes
communication between devices and a host controller (usually a personal
computer) USB has effectively replaced a variety of interfaces such as serial
and parallel ports. USB can connect computer peripherals such as mice,
keyboards, digital cameras, printers, personal media players, flash drives,
network adapters, and external hard drives. For many of those devices, USB
has become the standard connection method. USB was designed for personal
computers, but it has become commonplace on other devices such as
smartphones, PDAs and video game consoles, and as a power cord. Many
devices connected by USB do not need a power source of their own.
The following is a list of the most commonly used effects that are used to alter
analogue and digital sound. Effects devices can be either hardware based (physical
machines) or software based (programs or plug-ins on a computer).
Chorus - An audio effect used to "expand" or "thicken" a sound by playing
multiple versions of the input signal with slightly different delays and
changes in pitch simulating an ensemble of the input sound.
Compression -"Squashing" sound so that the difference between highest
and lowest level of the sound is lessened. This usually means amplifying
lower level signals, resulting in a sound that is perceived as louder and more
Delay - An effect that is used to add depth or space to an audio signal by
repeating the input one or more times after a brief pause of a few
milliseconds to a few seconds. Delay is also often referred to as echo.
Distortion, Overdrive and Fuzz - Effects applied to the electric guitar, the
electric bass, and other amplified instruments such as the Hammond organ,
synthesizers, harmonica and even vocals by electronically clipping the signal.
This adds sustain and additional harmonics to the signal.
Equalizer (EQ) - A device used to cut and boost individual frequencies of
an audio signal using a number of filters. The name "equalizer" comes from
the original application of correcting distorted audio signals to sound closer
to the original source. Graphic Equalizer and Parametric Equalizer are
different types of equalizers used by audio equipment and software Plug-Ins.
Filter - A function that cuts off a specific frequency band to change a sounds
brightness, thickness and other qualities. A few common filter types are Low-
Pass Filter, High-Pass Filter and Band-Pass Filter.
Low-Pass Filter Used to eliminate high-range frequencies resulting in a
Hi-Pass Filter Used to eliminate low-range frequencies resulting in a crisper
sound, good for creating percussion sounds.
Band-pass Filter Used to eliminate high- and low-range frequencies around
a specific frequency, resulting in more distinctive sound.
Flanger - An audio effect created by varying a slight delay between two
identical audio signals that results in a sound similar to a jet airplane taking
off or landing.
Phaser - An audio signal processing technique used to filter a signal by
creating a series of peaks and troughs in the frequency spectrum. The
position of the peaks and troughs is typically modulated so that they vary
over time, creating a sweeping effect. For this purpose, phasers usually
include a low frequency oscillator.
Pitch Shifter - A sound effects unit that raises or lowers the pitch of an
audio signal by a preset interval. For example, a pitch shifter set to increase
the pitch by a fourth will raise each note four diatonic intervals above the
notes actually played. Simple pitch shifters raise or lower the pitch by one or
two octaves, while more sophisticated devices offer a range of interval
alterations. Pitch shifters are included in most multi-effect processors today.
Pitch Correction - The process of correcting the intonation of an audio
signal without affecting other aspects of its sound. Pitch correction first
detects the pitch of an audio signal by looking for a periodic repeating
waveform and then calculating the time difference from these periodic
waveforms. The widest use of pitch correctors is in Western popular music
on vocal lines.
Reverb - An effect that simulates natural reverberations (sound reflections)
that occur in different rooms and environments to create an ambience or
sense of spaciousness.
Richard Bogen MT-BC
Desktop Music Handbook Glossary
Audio Recording Terms Glossary/Index
Blaze Audio Glossary of Audio Terms
The Sonic Spot
Music Technology Dictionary
Ableton Live Tutorial Videos