The chord types shown in Example 4 occur on steps 1, 3, 5 and 7 of
Mode 2 (or steps 2, 4, 6 and 8 of Mode 1). There are more chords
possibilities here, especially for more complex tertian chords.
Chords containing tritones and dominant funtioning chords are
common in this group. Note the polychord made of two diminished
seventh chords (the last chord). Not all complex chord possibilities were
included in this example.
Example 4: Chords on Steps 1, 3, 5 and 7 of Mode 2
There are only two transpositions that produce a true key change
(i.e., a new collection of pitches), up a minor second or up a
major second. The melodic inversion of these intervals produces the same transposition. All other transpositions produce the original
collection of notes.
The recurring or redundant features discussed above tend to limit
how long octatonic passages can be used to sustain interest. On
the other hand, an octatonic passage adds fresh harmonies and
stresses that give relief to more conventional materials. It can
be used to good poetic effect.
Because minor thirds and tritones recur so frequently, octatonic
passages always carry the tint of the tritone. Moreover, the
underlying harmonies of octatonic passages tend toward tritone
bearing chords, especially the hues of altered dominant and
leading tone chords.