theory from Frank Singer.comExtensions and Tensions | print this page | close this window |


The basic tools of harmony are the triad and the seventh chord. Both structures are built in thirds or skips. This process uses the odd-numbered scale-degrees.

If this process is continued past the octave marker (scale-degree eight), with the scale being repeated at higher registers, then the odd-numbered tones nine, eleven, thirteen, fifteen, seventeen, nineteen, twenty-one, and twenty-three result. These tones are called scale extensions.

scale degree 1 3 5 7 9 11 13 15 17 19 21 23
example in C C E G B D F A C E G B D
application triad seventh most 7ths dim. 7ths 7sus4 23rd extensions

Like most chord tones, the tensions can be altered to fit the function, applying the formula change: b, #, bb, or in the case of 23rd chord extensions, (double-sharp).

The chord tones [1 - 3 - 5 - 7] and conventional tensions [9 - 11 - 13] are the typical tools of the American Musician. 23rd chord extensions are a logical outgrowth of the development of chromatic harmony in conjunction with jazz improvisational approaches involving a linear approach to chords [chord-tones and tensions]. This technique has been used in classical music and by some jazz improvisers, amongst them Eric Dolphy, David Murray, and Bruce Gertz.

 Imaj7 1 3 5 7 9 #11 13 #15 #17 #19 b21 #23
example in C C E G B D F# A C# E# G# Bb D#
application chord tones conventional tensions 23rd chord extensions
 IImin7 1 b3 5 b7 9 #11 13 #15 #17 #19 21 23
example in C C Eb G Bb D F# A C# E# G# B D
application chord tones tensions [ conventional 11 is natural ] 23rd chord extensions
 V79, 13 1 3 5 b7 9 #11 13 #15 #17 #19 21 #23
example in C C E G Bb D F# A C# E# G# B D#
application chord tones conventional tensions 23rd chord extensions
 IIm7b5 1 b3 b5 b7 9 11 b13 b15 17 19 bb21 b23
example in C C Eb Gb Bb D F Ab Cb E G Bbb Db
application chord tones conventional tensions [ can also take b9 ] 23rd chord extensions
 Io7delayed resolution 1 b3 b5 bb7 9 11 b13 b15 17 19 b21 b23
example in C C Eb Gb Bbb D F Ab Cb E G Bb Db
application chord tones conventional tensions 23rd chord extensions
 V7sus4 1 4 5 b7 9 #11 13 #15 17 #19 21 #23
example in C C F G Bb D F# A C# E G# B D#
application chord tones conv. 23rd conv. 23rd conv. 23rd ext.

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