Modal Music
Modal music predates Tonal music. As Fretsource has pointed out, in the "medieval pop music" of the British Isles and Northern Europe, modes were keys. So depending on the "mood" the composer was striving for, a piece could have been written in C Ionian, C Aeolian, C Mixolydian or C Dorian.
To better understand the sound of a Mode as Key, we need to turn to our old friends One, Four and Five.
Ionian Mode: I IV V
Dorian Mode i IV v
Aeolian Mode i iv v
Mixolydian I IV v
In some modal tunes the bVII is used instead of the v.
This was a rigid structure. A specific mode, its diatonic harmonies and possibly counterpoint was all. No chromaticism, no modulation. In other words, strictly Diatonic.
Notice that only the Ionian mode has a V (Dominant Major). The other modes all have a v (Dominant Minor). The Dominant Minor does not provide the strong resolution to the tonic that the Dominant Major does. This is one of the prime reasons that the harmonic minor was developed.
The usage of modes in rock and jazz in the 20th Century to the present generally involves such things as extended one chord vamps (4, 8, 16 or more bars), two chord vamps (one bar each) or several different modes with the same root played over a pedal bass or power chords.
Tonal Music
In music theory, the key identifies the Tonic triad, the Major or Minor chord, which represents the final point of rest for a piece, or the focal point of a section. Although the key of a piece may be determined from the key signature, the establishment of key is actually brought about through functional harmony, a sequence of chords leading to one or more cadences.
Many musicians confuse key with scale, a scale is an ordered set of notes typically used in a key, while the key is the center of gravity, established by particular chord progressions.
The chords used within a key are generally drawn from the major or minor scale associated with the tonic triad, but may also include borrowed chords, altered chords, secondary dominants, and the like. All of these chords, however, are used in conventional patterns which serve to establish the primacy of the tonic triad.
Simple songs may stay in a single key throughout while more complex songs may modulate through one or more keys before returning to the original key.
Regards,
Monk
|