distortion synthesis
{{Short description|Set of electronic sound synthesis techniques}}
Distortion synthesis is a group of sound synthesis techniques which modify existing sounds to produce more complex sounds (or timbres), usually by using non-linear circuits or mathematics.Nb. Some authors refer to these techniques as 'modulation synthesis'; e.g. Chapter 6 of {{cite book|last=Roads|first=Curtis|title=The computer music tutorial|year=1996|publisher=MIT Press}}
While some synthesis methods achieve sonic complexity by using many oscillators, distortion methods create a frequency spectrum which has many more components than oscillators.
Some distortion techniques are: FM synthesis,Dodge 1997, pp.115-138 waveshaping synthesis,{{cite journal|last=Roads|first=Curtis|date=June 1979|title=A Tutorial on Non-Linear Distortion or Waveshaping Synthesis|journal=Computer Music Journal|publisher=MIT Press|volume=3|issue=2|pages=29–34 |jstor=3680281|doi=10.2307/3680281}}Dodge 1997, pp.139-157 and discrete summation formulas.Dodge 1997, pp.158-168
FM synthesis
Frequency modulation synthesis distorts the carrier frequency of an oscillator by modulating it with another signal. The distortion can be controlled by means of a modulation index.{{cite journal
| author = J. Chowning
| year = 1973
| title = The Synthesis of Complex Audio Spectra by Means of Frequency Modulation
| journal = Journal of the Audio Engineering Society
| volume = 21
| issue = 7
}}
The method known as phase distortion synthesis is similar to FM.
Waveshaping synthesis
Waveshaping synthesis changes an original waveform by responding to its amplitude in a non-linear fashion.Arfib, D. 1979. "Digital synthesis of complex spectra by means of multiplication of non-linear distorted sine waves." Journal of the Audio Engineering Society 27: 10.Marc Le Brun. "Digital Waveshaping Synthesis" in Journal of the Audio Engineering Society, 27(4), 1979, p250-266. It can generate a bandwidth-limited spectrum, and can be continuously controlled with an index.
Discrete summation formulas
DSF synthesis refers to algorithmic synthesis methods which use mathematical formulas to sum, or add together, many numbers to achieve a desired wave shape.Moorer, J. A. (November 1976). "The Synthesis of Complex Audio Spectra by Means of Discrete Summation Formulae". Journal of the Audio Engineering Society, 27(4), pp.717-727. This powerful method allows, for example, synthesizing a 3-formant voice in a manner similar to FM voice synthesis.{{cite journal|last=T Stilson|author2=J Smith|title=Alias-free digital synthesis of classic analog waveforms|journal=Proc. Int. Comp. Music Conf. (ICMC'96 Hong Kong)|year=1996|pages=332–335|citeseerx = 10.1.1.60.4437}} DSF allows the synthesis of harmonic and inharmonic, band-limited or unlimited spectra, and can be controlled by an index. As Roads points out, by reducing digital synthesis of complex spectra to a few parameters, DSF can be much more economical.C. Roads 1996, p.260-61.
Notable users
Jean-Claude Risset was one notable pioneer in the adoption of distortion methods.
References
- {{cite book|last=Dodge|first=Charles|title=Computer Music|url=https://archive.org/details/computermusicsyn00dodg_056|url-access=limited|year=1997|publisher=Schirmer Books|isbn=0-02-864682-7|pages=[https://archive.org/details/computermusicsyn00dodg_056/page/n134 115]–168|author2=Thomas A. Jerse|location=New York|chapter=5. Synthesis Using Distortion Techniques}}
- {{cite book
| last = Chowning
| first = John
|author2=Bristow, David
| year = 1986
| title = FM Theory & Applications - By Musicians For Musicians
| publisher = Yamaha
| location = Tokyo
| isbn = 4-636-17482-8
}}