Tonality and Modality
This long chapter, sections A through R (18 pages in all), covers all the essential information regarding tonal, or functional, harmony. Chapter 6 applies that information to the actual task of part writing and composition.
To begin, we must further clarify the distinction between what we refer to as modality and what we refer to as tonality.
Distinguishing Modality from Tonality
Tonality, on the one hand, could be broadly defined as any musical system for which a single note serves as a central or unifying tone. From this definition, clearly all the music we have studied to date, including Indian classical music, is tonal, because even modal musics and the chants and ragas have a central tone around which all the other notes are arranged, sometimes represented by an ever-present drone.
But for the purposes of this class, a more narrow version of tonality is implied. For our purposes, tonality is the system of 12 related major and minor scales that serve as a basis for the creation of triads and seventh chords above and below a central tonic. These chords then relate to each other in progressions that define a central key.
In Western music, modality is the more ancient system of organized scales based on the displacement of the tonic note along a arrangement of seven natural tones, as codified by the seven "church modes." In other cultures, such as the Indian system, modality is seen as the bringing together of a great many different scales (ragas), all based on the same central tonic.
In modern composition and in rock and jazz music, modality has come to mean the use of scales that are not the standard major scale and its paired relative minor. "Modal jazz" for example is jazz that emphasizes the Dorian mode, or perhaps the Phrygian. (Recall the soundfile of "So What" from the first chapter). In this way, modern modality is closer to the Indian music system than it is to the system of the church modes, and is in fact why jazz music and Indian classical improvisational music have much in common.
In this way, modality is seen as a melodically based system, whereas tonality is based around the creation and employment of chords. The reason tonality, the major-scale/minor-scale system, came to dominate music is because of the ease at which a balanced system of chords can be created using the notes of the major scale. This sections of this chapter are dedicated to exploring the "balance" of the tonal system.
What, then, distinguishes the melodic aspect of modality from the harmonic aspect of tonality? It is the construction of triads, or three-note chords, above and below a central tone. While there will be much more to say about chords in future pages, let us begin by looking at chords from the standpoing of harmonic polarity.
Contrasting Major and Minor
Historically, in Western music, the system of church modes became consolidated during the 17th century into a system based on just two of them: the major (Ionian) and the minor (a conflation of Aeolian and Dorian with some Phrygian). This evolved into a system we call tonaiity, which can also be called the major-minor system. In such a system, scales based around a root note give birth to chords of major and minor quality.
The polarity of major and minor is demonstrated in two ways. One is the polarity of the Major and the Phrygian modes, and the other is the polarity of the Major and the Relative minor (which is the same as the Aeolian).
The symmetry of Major and Phrygian
The fundamental polarity of major and minor is reflected in the major scale and its symmetrical cousin, the phrygian mode. The arrangement of whole tones and semitones for the ascending major scale is precisely mirrored by the descending version of the Phrygian scale: WWHWWWH. Check this out for yourself to make sure.
One excercise I always give music majors is to play the major scale ascending and the Phrygian scale descending, around the cycle of fifths. If you are a music major, you may just want to do this right now on your instrument. It's an excellent excercise!
The pairing of Major and Aeolian (relative major and minor)
Another polarity, which more directly informs the major-minor system, is the polarity between the major mode and the natural minor, which we can now easily see as the relationship between the Ionian and Aeolian mode:
Upon this fundamental polarity of related major and minor scales, the entire system of functional harmony has been founded. Historically, music theory and musical practice coelesced around the pairing of the Ionian mode and Aeolian mode, with the observation that the two scales share the same key signature.
We have already seen, when studying key signatures and the cycle of fifths, how relative major and minor keys share the same key signature. This concept then carries over to the pairing of a major scale with that of its relative minor. C major and A minor share the same key signature, and the scales are closely related to each other for this very reason. This holds true around the cycle of fifths: F major/D minor, G major/E minor and so on.
Now that you have learned the cycle of fifths and the system of key signatures, it is easy to see how the set of 24 major and minor scales are based on this set of 12 major key signatures, with their relative minors.
NEXT: 5B Introduction to Harmonic
Polarity