A Player's Guide to Chords and Harmony by Jim Aikin Page A

toward the tonic or away from it.
    This fact opens up some interesting compositional possibilities. A composer can add tension to a chord progression by violating our expectations with respect to the tonic. For instance, a piece might not begin on the tonic. As a young man, Beethoven served notice to the audiences in Vienna that he was a force to be reckoned with by beginning his Fitst Symphony not on the tonic but on a somewhat distant chord. In the pop realm, the jazz standard "Autumn Leaves" uses the same technique.
    Next to the tonic, the most important diatonic chord is the dominant - the V chord. From the 18th century onwards, the chord progression V-I - a dominant followed by a tonic - has been the most important progression in European/ American music. This progression strongly emphasizes the tonic as a point of rest. Consequently, the dominant chord is felt to provide a kind of tension that demands resolution through movement to a tonic. Many classical symphonies in the late 18th and early 19th centuries ended with a string of dominant-tonic progressions; a typical example is shown in Figure 4-9. This type of ending hammered home the tonic as the final resting point in the piece.

    Next in importance to the dominant and tonic is the subdominant. Looking at Figure 4-9, you might think this note/chord gets its name from the fact that it's the scale step below the dominant ("sub-" is a Latin prefix that means "below"). But in fact the name is derived from the fact that the dominant is a 5th above the tonic, while the subdominant is a 5th below the tonic.

    Figure 4-9. The dominant-tonic (V-1) progression is the most important progression in the classical music of the late 18th and early 19th centuries. The progression shown here, which alternates V and I chords in the key of C, illustrates how a symphony written in this period might come to its thrilling conclusion.
    In music of the late 18th and early 19th centuries (the so-called Classical period in classical music), the subdominant was often deployed just before the dominant in a progression leading back to the tonic. This IV-V-I progression is shown in Figure 4-10. This progression is still used in many modern pop tunes, especially in country and folk music, which tend to use relatively simple changes. In jazz and jazz-derived styles, however, the IV has been largely supplanted by the minor II chord, also shown in Figure 4-10. If you play these progressions, you should be able to hear that the IV chord (the subdominant) and the minor II chord are similar in sound, and perform a similar harmonic function. The minor II chord in first inversion was often used in place of the IV chord in Classical progressions as well.

    Figure 4-10. The IV-V-I progression, used in traditional classical music, and the II-V-I progression, used more often in jazz, are similar.

     

PHRASES & CADENCES
    It's useful to look at a piece of music of any significant length not as a single seamless entity, but as a series of phrases. The end of each phrase flows into the beginning of the next, usually without a pause. The most common lengths for phrases are four and eight bars, but odd-length phrases, such as five or ten bars, are by no means unusual.
    The division of a longer piece into phrases usually feels very natural. As you listen to music, you'll probably be able to identify phrases without trouble. If you're in doubt, when looking at sheet music, about where one phrase ends and the next begins, try counting out groups of four or eight bars. Chances are, you'll be able to find the phrases this way.
    The portion of a chord progression that ends a phrase is called a cadence. As you can probably anticipate from the section above on "The Importance of the Tonic," many cadences end on the I chord. A cadence in which the I is preceded by a V (for an example, see Figure 4-9) is called a full cadence or an authentic cadence. But not all cadences are full cadences. For that matter, not all V-I