Understanding All I Know About That: What did you discover about the harmonica as you played and read articles on the web? Did you find that blowing out generates stable pitches, and that drawing in breath generates unstable pitches?

Scale degree tendencies. Discussion: What drives Western music? Answer: Diatonic scale degree tendencies.

What drives Western music? The ebb and flow of scale degree tendencies, for one thing. Psychologically, music can be explained as a journey or a story, involving conflict and resolution, or dissonance and consonance, going away and coming home. Home, in Western music, is tonic and the stable scale degrees. (Next time, we will find out why those scale degrees are the stable ones).

Notice some things about how the major scale works:
Scale degrees 1, 5 and 3 (in that order) are stable,
And scale degrees 7, 4, 2, and 6 (in that order) are unstable.
The notes of a harmonica illustrate stable and unstable scale degrees perfectly. The notes played breathing out are stable, and the ones played breathing in are unstable.

Before we go any further, understand this: As we study worship music, we are studying pop music styles. Pop music is EAR music. Actually, all music is ear music. But in the case of pop, it might not ever be written down, and musicians find ways of describing what they are playing, based on patterns that they hear, not notes that they read. Some styles of jazz are based more on notation (such as big band charts), and almost all art music (classical) has some objective notation. But folk, worship and other pop styles are often more improvisatory and aural. So we are trying the impossible here; to write down and understand music that is aurally conceived and played.

Bass Law, very simply, is the tendency of the bass line to resolve by going up a fourth (or down a fifth, which is an inversion of the same movement). This movement is the strongest of bass movements, even stronger than going up a second or down a second, stronger than going up or down an octave, certainly stronger than an arpeggiation of the pitches of a triad. All of those movements make sense to a bass player or to a singer of a bass part, but none is as strong as going up a fourth. It can be understood several ways, but all point to the same phenomenon:

• The opening of many songs begin with a strong 5 to 1 melodic leap. (We can quickly recall 10 or 20 songs that begin this way). It’s a strong movement! Notice that the melody, while leaping up a fourth, is not going from tonic to 4, but is almost always going from 5 to 1.
• In the overtone series, the first non-root pitch is the dominant (the 3rd harmonic, or 2nd overtone). It strongly wants to move up to the tonic, too.
• In a Perfect Authentic Cadence, the bass note wants to go from 5 to 1.
• A forward motion through the circle of fifths is really moving to the left and going through a “circle of fourths.” That is actually a better way to think about the circle, and from now on in the class I want you to create the circle by going through fourths, so that they become automatic to you.
• Notice the tuning of the lower strings on a guitar (ALL the strings on a bass guitar) is in fourths. That’s in part because going up a fourth is the most natural movement for a bass to travel.
• Soon, we are going to see that the strength of this bass movement going up a fourth is enough to allow us to create not only a PAC, but to move away from tonic to other chords and to flow smoothly back to tonic. It’s a very strong movement.
• This, by the way, is how the plagal cadence comes to feel so final. We have PACs several times through a piece, and at last we arrive at the final one. How do we establish (especially in a hymn) that this is not just the end of another stanza, but the end of the last stanza? We continue the bass up one more fourth, overshoot the tonic, as it were, and then settle back down.

Let’s review our catechism: What is music theory? The theory of what makes music “work.”
What drives Western music? SDT + BL = PAC (Scale Degree Tendencies plus Bass Law generates Perfect Authentic Cadence)