Editing Tritone substitution (section)

===Classical===

Classical harmonic theory would notate the substitution as an [[augmented sixth chord]] on {{music|flat}}II (the augmented sixth being enharmonic to the dominant/minor seventh). The augmented sixth chord can either be the [[Augmented sixth chord#Italian sixth|Italian sixth]] It<sup>+6</sup>, which is enharmonically equivalent to a dominant seventh chord ''without'' the fifth; the [[Augmented sixth chord#German sixth|German sixth]] Gr<sup>+6</sup>, which is enharmonically equivalent to a dominant seventh chord ''with'' the fifth; or the [[Augmented sixth chord#French sixth|French sixth]] Fr<sup>+6</sup>, which is enharmonically equivalent to the Lydian dominant ''without'' the fifth but with a sharp eleven, all of which serve in a classical context as [[Predominant chord|predominant]] chords, functioning similarly to a ii chord in a [[Ii–V–I progression|ii - V - I]] chord sequence. This can also be seen as a substitute for the [[secondary dominant]] of V.<ref>Satyendra, Ramon. "Analyzing the Unity within Contrast: Chick Corea's ''Starlight''", p.55. Cited in Stein.</ref><ref>Stein, Deborah (2005). ''Engaging Music: Essays in Music Analysis''. New York: Oxford University Press. {{ISBN|0-19-517010-5}}.</ref>

Below is the original dominant-tonic progression, the same progression with the tritone substitution, and the same progression with the substitution notated as an Italian augmented sixth chord:

[[File:Tritone substitutions.png|thumb|center|400px|Original {{audio|Tritone substitutions V7-I.mid|Play}}, tritone substitution {{audio|Tritone substitutions bV7ofV-I.mid|Play|help=no}}, and augmented sixth chord {{audio|Tritone substitutions It6-I.mid|Play|help=no}}]]