Choral Public Domain Library

The octatonic scale/mode produces some lovely and interesting sounds, especially in choral music. The Wikipedia article on the Octatonic scale is an excellent (and accurate) resource.

[ Edit Another resource which has good musical examples is Kenneth Rumery's Octatonic scale page. ]

A few comments:

The 1st, 3rd, 5th, and 7th tones form a diminished chord - and likewise the 2nd, 4th, 6th, and 8th tones form a diminished chord. Interestingly enough, when the tones of the octatonic scale are subtracted (removed) from the chromatic scale, the four tones which remain also form a diminished chord.

Thus if one considers the octatonic scale:

... C=B# C# D# E F# G A Bb C=B# ...

then the omitted tones form the diminished chord:

... D F G#=Ab B D ...

Of the three distinct octatonic series (which could now be characterized by the omitted diminished chord), the one given above has two additional "reflective" (or "inversive") symmetries with respect to the keyboard (which, in my view makes this particular octatonic series the "preferred" one):

D lies between the black-key pair C# D#, and G#=Ab is the center of the black-key triplet F# G#=Ab Bb. Reflecting the octatonic series about either D or G#=Ab pairs off the tones

C# --- D#
B#=C --- E
Bb --- F#
A --- G

in a way that is visually evident if one looks at them on a keyboard.

Another harmonically satisfying progression (creating a hauntingly beautiful effect when sung by a cappella voices) is the ascending sequence of chords:

C E G C ... root C major
C# F# A C# ... 2nd inversion F# minor
Eb G Bb Eb ... root Eb major
E A C E ... 2nd inversion A minor
F# A# C# F# ... root F# major
G C Eb G ... 2nd inversion C minor
A C# E A ... root A major
Bb Eb Gb Bb ... 2nd inversion Eb minor
C E G C ... and back to root C major

Singing this sequence a a cappella as a warn-up exercise is a great aid to learning the octatonic series and tuning the chords, while learning something of the tonal modality of the octatonic series.

Chuck Giffen

Chuck,

What interesting stuff! - although I'm sure my church choir would think I'd gone mad if I suggested any of it.

Thinking of someone else who did, er, unusual things to church choirs, what about the following sequence of 3-part chords for STB:

Going up:

C G Eb
Db Bb F
Eb B G#
F# C# A
G E B
A F D
C G Eb

and then the same in reverse going down again. The interesting thing is that while all the parts are going up in a series of seconds of various kinds (or their enharmonic equivalents), the tonality of each chord is a major second lower than the previous one: C minor, Bb minor, G# minor, F# minor, E minor, D minor, C minor. And so on up the whole-tone scale again.

Have you recognised the work of your greatest musical countryman yet? Yup, it's the "So teach us to number our days" verse of Ives's Psalm 90. Also very hauntingly beautiful and satisfying.

DF