Editing Power chord (section)

==Analysis==
When two or more notes are played through a [[Distortion (music)|distortion]] process that [[Nonlinearity|non-linearly]] transforms the audio signal, additional [[Harmonic series (music)#Partial|partials]] are generated at the sums and differences of the [[Audio frequency|frequencies]] of the [[harmonics]] of those notes ([[intermodulation distortion]]).<ref>Doug Coulter (2000). [https://books.google.com/books?id=QvM0jbfgTGkC&pg=PA293 Digital Audio Processing], p.293. {{ISBN|0-87930-566-5}}. "Any non-linearity produces harmonics as well as sum and difference frequencies between the original components."</ref> When a typical [[Chord (music)|chord]] containing such intervals (for example, a [[Major chord|major]] or [[Minor chord|minor]] chord) is played through distortion, the number of different frequencies generated, and the complex ratios between them, can make the resulting sound [[Roughness (psychophysics)|messy and indistinct]].<ref>[https://www.bbc.co.uk/dna/h2g2/A33659319 "Distortion – The Physics of Heavy Metal"] {{webarchive|url=https://web.archive.org/web/20091128181402/http://www.bbc.co.uk/dna/h2g2/A33659319 |date=2009-11-28 }}, ''BBC''</ref> This effect is accentuated as most guitars are tuned based on [[equal temperament]], with the result that minor thirds are narrower, and major thirds wider, than they would be in [[just intonation]].

However, in a ''power chord'', the ratio between the frequencies of the root and fifth are very close to the [[just intonation|just]] [[Interval (music)|interval]] 3:2. When played through distortion, the intermodulation leads to the production of partials closely related in frequency to the harmonics of the original two notes, producing a more coherent sound. The intermodulation makes the [[Frequency spectrum|spectrum]] of the sound expand in both directions, and with enough distortion, a new [[fundamental frequency]] component appears an octave lower than the root note of the chord played without distortion, giving a richer, more [[Bass (music)|bassy]] and more subjectively "powerful" sound than the undistorted signal.<ref>Robert Walser (1993). ''[https://books.google.com/books?id=YKPDF0I5p3kC&pg=PA43 Running with the Devil]'', p.43. {{ISBN|0-8195-6260-2}}.</ref> Even when played without distortion, the simple ratios between the [[harmonic]]s in the notes of a power chord can give a stark and powerful sound, owing to the [[resultant tone]] (combination tone) effect. Power chords also have the advantage of being relatively easy to play {{xref|(see {{slink||Fingering}})}}, allowing fast chord changes and easy incorporation into [[melody|melodies]] and [[riff]]s.