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Faculty of Music, University of Oxford
FHS 2012 – Logic Pro for Composers
Tutors: Mr Chris Ferebee ,Dr Duncan Williams
Seminar: n/a
Duration: n/a
Glossary of terms used in this course
This glossary covers terminology used throughout the course. You may wish to
follow the references below for further detail.
Seminar 1 Glossary
ADC
Additive synthesis
ADSR
Amplitude
Amplitude Envelope
Audio
DAC
DAW
DSP
Fourier theorem
Frequency
Analogue-to-digital converter. Processor which
converts voltage to binary data for signal processing
within DAW (analogous to sound – converted from
‘real sound’ when sound pressure changes move coil
or charged backplate to induce corresponding
variation in voltage output in a dynamic or capacitor
microphone)
Method for generating complex waveforms by
combining several oscillators
Attack – Decay – Sustain – Release. A way of
illustrating traditional amplitude envelopes
Absolute loudness, usually measured logarithmically
in dB (x) where x is a reference value (eg in volts, or a
fraction of volts, sound pressure, watts, or some other
reference value)
The temporal dynamic variation in the onset of a
sound
Human perception of sound pressure changes (usually
loudness, frequency, and timbre).
Digital-to-analogue converter. Processor which
converts binary data to voltage (analogous to sound –
converted to ‘real sound’ when passed through
loudspeaker to generate movement of air and
corresponding change in sound pressure)
Digital audio workstation. Computer equipped with
DAC/ADC hardware, signal processing/sequencing
software, and MIDI hardware
Digital signal processing
Jean-Baptiste Fourier stated that any complex
waveform (ie, any sound) can be reproduced by
combining the correct number of dynamically varying
sine waves.
The number of cycles of a signal, measured in Hz,
inversely proportional to velocity/wavelength. Longer
wavelengths result in lower frequencies. Lower
frequencies are traditionally perceived as ‘bass’
frequencies. Typical human hearing range is usually
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Faculty of Music, University of Oxford
FHS 2012 – Logic Pro for Composers
Tutors: Mr Chris Ferebee ,Dr Duncan Williams
Gain
Harmonic
LFO
Loudness
Max
MIDI
Modifier keys
MSP
Object
Partial
Patcher
(and incorrectly) quoted as 20 – 20,000 Hz (see
Nyquist theorem)
Traditionally a voltage gain applied to signals to
amplify or attenuate their volume
Integer multiple of fundamental frequency component
of a signal (usually lowest prominent frequency, but
can vary dependent on signal type)
Low frequency oscillator. A particular and common
type of signal manipulation used in many synthesiser
designs. An oscillator with a low number of cycles per
second (typically <30 Hz) is connected to the
frequency or amplitude inlet of another signal
generator, to create vibrato and tremolo effects,
respectively.
Perceptual measure of volume. Product of sound
pressure and frequency (see References –
Fletcher/Munson equal loudness contour). Bass
frequencies appear more prominent when reproduced
at higher sound pressure level.
Data processing objects and pathways in Max/MSP.
Also debugging window in Max/MSP
Musical Instrument Digital Interface. Data format
which allows musical information (note on, note off,
pitch, loudness, pan, modulation etc) to be transmitted
between controller keyboards, synthesisers, drum
machines, and DAW for sequencing (amongst many
other types of hardware). Typically uses 5-Pin DIN
connector, cables are male-male. MIDI thru transmits
an exact copy of MIDI in on MIDI capable equipment.
Keys used to active shortcuts on Apple Mac computers.
Ctrl-Alt-Cmd (Control, Option, Command/Apple). Also
shift, tab. Ctrl-click usually corresponds to a ‘right
click’ on a Windows machine. Cmd-x usually
corresponds to equivalent shortcuts on Windows
machines (eg, Cmd-O opens a file, Cmd-P prints, Cmd-C
copies, Cmd-X cuts, Cmd-V pastes etc).
Signal processing objects, modules, and pathways in
Max/MSP. Can be connected to Max objects.
Graphical programming elements used by both Max
and MSP for a variety of tasks. Basis of all work in
Max/MSP. Connected via patch cords to ‘inlets’. Altclicking an object opens a ‘help’ patcher with
examples.
Inharmonic overtone (see harmonic and timbre)
A window allowing Max and MSP objects to be
connected to facilitate signal generation and
processing in Max/MSP. Cmd-clicking patcher ‘locks’
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Faculty of Music, University of Oxford
FHS 2012 – Logic Pro for Composers
Tutors: Mr Chris Ferebee ,Dr Duncan Williams
Pitch
Sawtooth
Sine wave
Square Wave
Timbre
Triangle Wave
Delay
Echo
Equalisation
Filtering
Noise
Q
Reverberation
or ‘unlocks’ the patcher for editing.
Perceptual measure related to frequency. Mel scale is
the just-noticeable-difference between one pitch and
another. Frequency (in Hz, Hertz), usually used as
shorthand.
More complicated signal type – a harsh signal with
even and odd harmonics with a ratio of 1/f
Basic signal type comprised of one oscillator at one
frequency. Also known as a sinusoidal wave.
Signal type with only odd harmonics at 1/f
Distinguishing element(s) of sound, apart from
loudness and pitch. Eg, A4 played on piano, with equal
loudness to A4 played on trombone, has a notably
different sound. This is usually characterised by
spectral shape (harmonic or inharmonic overtones aka
partials), but can also be due to temporal acoustic
correlations.
Signal type with only odd harmonics at 1/fn^2
Used in two contexts in Max/MSP programming. In
Max, a handy mathematical device to retrigger ‘bang’
objects. In MSP (and other audio contexts), an audio
effect which causes a repeat (echo, echo, echo). Usually
incorporates a ‘feedback’ control, which dictates the
number and type of repeats.
Laymans term which might mean delay or
reverberation, or a combination of both.
Developed by telephony engineers, practical
application of a series of filters to ‘equalise’ signals
which were not even across the frequency range. Can
now include linear-phase equalisation whereby phase
changes and unwanted frequency smearing is
compensated by subsequent phase adjustment in the
complete signal.
A process of deliberately adjusting the phase of
selected frequency components in a signal to amplify
or attenuate them by positive or negative phase
interference. Powerful sound shaping device.
Typically white noise, a signal which has equal
amplitude across the full frequency range. Also pink
noise (equal amplitude per octave, a commonly used
musical test signal)
See width
More traditional echo effect than delay – usually the
sound of a real acoustic space. Large spaces have long
decaying reverberation. Small spaces (tiled bathrooms
etc) have shorter reverberation, which might include
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Faculty of Music, University of Oxford
FHS 2012 – Logic Pro for Composers
Tutors: Mr Chris Ferebee ,Dr Duncan Williams
Subtractive synthesis
Width
Balanced line
Capacitor
microphone
Dynamic microphone
‘flutter’ echoes. Commonly now associated with
mathematical convolution – a multiplicative signal
processing device.
Alternative to additive synthesis, whereby complex
waveforms are created from noise using filtering. Good
for noisy signals, or useful if combined with some
additive synthesis to create hybrid signal types (eg
voice)
In conjunction with frequency and gain, the third
control used by a fully parametric equaliser. Width
specifies the spectral range around the target
frequency that will be amplified or attenuated by the
gain of the equaliser
Minimum 2 core connection which carries a copy of
the ‘hot’ signal out of phase. At receiver, ‘cold’ signal is
inverted, causing positive phase interference with the
original ‘hot’ signal, but negative phase interference
with any unwanted induced noise incurred across the
length of the cable run – effectively allows cable runs
to be longer, and carry cleaner signals. Used in all
professional audio contexts, including most
microphones (not used by most HI-Fi, eg Phono
connectors!).
Device for converting sound pressure changes into
voltage. Uses a charged backplate and moving front
plate to induce voltage changes when moved by sound
pressure. Typically associated with studio recording
and higher frequency response.
Device for converting sound pressure changes into
voltage. Uses a moving coil wrapped around a semipermanent magnet to induce voltage changes when
moved by sound pressure. Typically associated with
live recording or higher SPL recording tasks in studio
recording (kick drums and other percussion shells,
distorted electric guitar, rap vocals)
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Faculty of Music, University of Oxford
FHS 2012 – Logic Pro for Composers
Tutors: Mr Chris Ferebee ,Dr Duncan Williams
Compression
De-esser
Expansion
Nyquist theorem
Plosives
Sampling
Sibilance
Method for reducing the dynamic range of an audio
signal by automatically reducing the level of signals
beyond a threshold
A combined dynamic and frequency sensitive signal
processing routine which reduces the level of signals
above a threshold only in specified frequency range
(usually used to target the sibilant frequency of female
vocal recordings, but also used to reduce overly bright
recordings in mastering process)
Method for increasing the dynamic range of an audio
signal by automatically increasing the level of signals
beyond a threshold (often used as a ‘noise gate’ for
silencing amplifier hiss, unwanted background noise
and so on)
Theory which states that frequency of sampling (aka
sample rate or the number of samples taken per
second) should be at least twice the frequency of the
highest frequency being sampled. Eg, a bass note at
1000 Hz should be sampled at least 2000 times per
second. Failure to follow this rule can cause aliasing
distortion, an unpleasant ‘folding over’ of the
uncaptured frequencies.
Bassy-thud caused by ‘b’ and ‘p’ consonants, usually in
male vocal recording
Part of the ADC process, wherein a series of measures
of amplitude, frequency, and phase are taken of an
input signal, to represent the signal in a given number
of binary data. More samples equates to a better
representation of the orginal signal (analogous to dotmatrix printers and painting – more dots looks
smoother).
Snake-like hiss sound, often in female vocals, on ‘s’ and
‘t’ consonants.
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Faculty of Music, University of Oxford
FHS 2012 – Logic Pro for Composers
Tutors: Mr Chris Ferebee ,Dr Duncan Williams
Analysis
FFT
FT
Morphing
Phase
Resynthesis
STFT
Vocoding
Wavelets
Usually a Fourier analysis – assesses in input signal to
establish its frequency, amplitude, and phase
components
Fast Fourier Transform – a quick STFT
Fourier Transform (aka fourier analysis) – establishes
all of the frequency components in a signal, and their
relative magnitudes
A technique for creating a hybrid sound, with
characteristics derived partly from a source and target
sound
Measure of position in a cycle. Can cause positive
interference – increase in volume, or negative
interference – decrease in volume, if two signals with
the same frequency and differing phase are combined.
Sometimes used for this purpose to create ‘swirling’
sound effects.
Strictly this is usually combined with analysis, and
should just be synthesis, but is called resynthesis to
clarify that an input signal has been generated as
closely as possible by synthesis rather than sampling.
Short time Fourier Transform –a FT over a short
period of time
Sound hybridisation system for
bandwidth reduction in telephony, in which
a hybrid sound is generated by combining
properties derived partly from the target sound
(the spectral envelope of speech, or tonal properties),
and partly from the source sound
(the noise being filtered).
Series of independent signals with independently
varying amplitude, frequency, and phase envelopes.
Used for variety of signal processing tasks and novel
sound manipulation (eg morphing).
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Faculty of Music, University of Oxford
FHS 2012 – Logic Pro for Composers
Tutors: Mr Chris Ferebee ,Dr Duncan Williams
References
Analysis, Synthesis, and Perception of Musical Sounds: The Sound of Music
(9781441921864): James W. Beauchamp
Computer Music: Synthesis, Composition, and Performance (9780028646824):
Charles Dodge, Thomas A. Jerse
Psychoacoustics: Facts and Models: Eberhard Zwicker, Hugo Fastl, Springer
2002
Lee, K.H., Davies, P. & Surprenant, A., 2003. Methodology for quantifying the
tonal prominence of frequency modulated tones. Journal of the Acoustical
Society of Americal, 114(4), 2352-2352.
Serra, X. & Bonada, J., 1998. Sound Transformations Based on the SMS High Level
Attributes. In International Conference on Digital Audio Effects. Barcelona.
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