Onset refers to the beginning of a
musical note or other sound. It is related to (but different from) the concept of a
transient
ECHELON, originally a secret government code name, is a surveillance program ( signals intelligence/SIGINT collection and analysis network) operated by the five signatory states to the UKUSA Security Agreement:Given the 5 dialects that ...
: all musical notes have an onset, but do not necessarily include an initial transient.
Onset detection
In
signal processing, onset detection is an active research area. For example, the
MIREX annual competition features a
Audio Onset Detection contest
Approaches to onset detection can operate in the
time domain,
frequency domain,
phase domain, or
complex domain
In mathematics, a complex number is an element of a number system that extends the real numbers with a specific element denoted , called the imaginary unit and satisfying the equation i^= -1; every complex number can be expressed in the form a ...
, and include looking for:
* Increases in spectral energy
* Changes in spectral energy distribution (
spectral flux) or
phase
* Changes in detected pitch - e.g. using a
polyphonic
Polyphony ( ) is a type of musical texture consisting of two or more simultaneous lines of independent melody, as opposed to a musical texture with just one voice, monophony, or a texture with one dominant melodic voice accompanied by chords, h ...
pitch detection algorithm
* Spectral patterns recognisable by
machine learning techniques such as
neural network
A neural network is a network or circuit of biological neurons, or, in a modern sense, an artificial neural network, composed of artificial neurons or nodes. Thus, a neural network is either a biological neural network, made up of biological ...
s.
Simpler techniques such as detecting increases in time-domain amplitude can typically lead to an unsatisfactorily high amount of
false positives or
false negatives.
The aim is often to judge onsets similarly to how a human would: so
psychoacoustically-motivated strategies may be employed. Sometimes the onset detector can be restricted to a particular domain (depending on intended application), for example being targeted at detecting percussive onsets. With a narrower focus, it can be more straightforward to obtain reliable detection.
See also
*
ADSR envelope ADSR may refer to:
* ADSR envelope (attack decay sustain release), a common type of music envelope
* Accelerator-driven sub-critical reactor, a nuclear reactor using a particle accelerator to generate a fission reaction in a sub-critical assembly ...
*
Prefix (acoustics)
References
* Bello, J.P., Daudet, L., Abdallah, S., Duxbury, C., Davies, M., Sandler, M.B. (2005
"A Tutorial on Onset Detection in Music Signals" IEEE Transactions on Speech and Audio Processing 13(5), pp 1035–1047
* Bello, J.P, Duxbury, C., Davies, M., Sandler, M. (2004)
"On the use of phase and energy for musical onset detection in the complex domain" ''IEEE Signal Processing Letters''
* Collins, N. (2005
"A Comparison of Sound Onset Detection Algorithms with Emphasis on Psychoacoustically Motivated Detection Functions" Proceedings of AES118 Convention
Psychoacoustics
Synthesizers
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