Editing Heavy metal music (section)

====Typical harmonic structures====
Heavy metal is usually based on riffs created with three main harmonic traits: modal scale progressions, [[tritone]] and chromatic progressions, and the use of [[pedal point]]s. Traditional heavy metal tends to employ modal scales, in particular the [[Aeolian mode|Aeolian]] and [[Phrygian mode]]s.<ref>Walser (1993), p. 46</ref> Harmonically speaking, this means the genre typically incorporates modal chord progressions such as the Aeolian progressions I-♭VI-♭VII, I-♭VII-(♭VI), or I-♭VI-IV-♭VII and Phrygian progressions implying the relation between I and ♭II (I-♭II-I, I-♭II-III, or I-♭II-VII for example). Tense-sounding [[chromatic]] or [[tritone]] relationships are used in a number of metal chord progressions.<ref>Marshall, Wolf. "Power Lord—Climbing Chords, Evil Tritones, Giant Callouses", ''Guitar Legends'', April 1997, p. 29</ref><ref name=MH>Dunn, Sam (2005). {{usurped|1=[https://web.archive.org/web/20180807081407/http://metalhistory.com/ "Metal: A Headbanger's Journey".]}} Warner Home Video (2006). Retrieved on 19 March 2007</ref> In addition to using modal harmonic relationships, heavy metal also uses "[[Pentatonic scale|pentatonic]] and blues-derived features".<ref name="Lilja 2009">{{cite journal |last=Lilja |first=Esa |date=2009 |title=Theory and Analysis of Classic Heavy Metal Harmony |journal=[[Advanced Musicology]] |publisher=IAML Finland |volume=1 }}</ref>

The tritone, an interval spanning three whole tones – such as C to F# – was considered extremely [[dissonant]] and unstable by medieval and Renaissance music theorists. It was nicknamed the ''diabolus in musica –'' "the devil in music".<ref>The first explicit prohibition of that interval seems to occur with the "development of [[Guido of Arezzo]]'s [[hexachord]]al system which made B flat a [[diatonic]] note, namely as the 4th degree of the hexachordal on F. From then until the end of Renaissance the tritone, nicknamed the 'diabolus in musica', was regarded as an unstable interval and rejected as a consonance" (Sadie, Stanley [1980]. "Tritone", in ''The New Grove Dictionary of Music and Musicians'', 1st ed. MacMillan, pp. 154–155. {{ISBN|0-333-23111-2}}. See also Arnold, Denis [1983]. "Tritone", in ''The New Oxford Companion to Music, Volume 1: A–J''. [[Oxford University Press]]. {{ISBN|0-19-311316-3}}</ref>

Heavy metal songs often make extensive use of [[pedal point]] as a harmonic basis. A pedal point is a sustained tone, typically in the bass range, during which at least one foreign (i.e., dissonant) harmony is sounded in the other parts.<ref>Kennedy (1985), "Pedal Point", p. 540</ref> According to Robert Walser, heavy metal harmonic relationships are "often quite complex" and the harmonic analysis done by metal players and teachers is "often very sophisticated".<ref>{{cite book |last1=Walser |first1=Robert|date=2014|title=Running With the Devil: Power, Gender, and Madness in Heavy Metal Music|page=47 |publisher=Wesleyan University Press}}</ref> In the study of heavy metal chord structures, it has been concluded that "heavy metal music has proved to be far more complicated" than other music researchers had realized.<ref name="Lilja 2009"/>