Jazz is rooted ( no pun) in traditional European music theory, fused with afro-cuban rhythms, early American folk, gospel, and the blues. A central concept in all of this stuff is the 7th chord.
What is UP with that crazy 7th chord, anyway? Its talked about so much be cause of its many forms, and its central function in music. Major, minor, dimiished, “half” diminished ( Berklee grad’s HATE this term!), dominant, altered. And the extensions of the 7th chors: 9th, 11th, 13th’s. Then the accidentals: raised this, lower that. The sequence of 7th chords, is most often structured in fourths, that is, moving up in fourth intervals within the established 12 tone cycle. (You can also think of moving DOWN in the cycle, moving in fifths, and you’ll product the same result.)
What’s gets to the heart of the matter is not about music, but more metaphysical. Nature oscillates; things grow and evlove in cycles over a period of “time”. Cycles are a result of mounting tension and the need for release. You feel hunger for example, and the tension continues until you eat thus “relieving” the tension. An apple grows from a tree, hanging, to the point where gravity has more power than the root, making the apple fall, and “relieving” gravitational tension. We become sleepy, because of mounting tension from the wears of the day, until the tension is relieved at bedtime - and vice-versa!
Back to music now, the 7th chord, most particulary the “dominant” 7th chord, creates a very unstable feeling. In fact it is known as the most unstable chord in the series. The hanging feeling is then “resolved” by its following “tonic” chord, making a satisfying feeling for the listener. This is really, the tension felt by the composer, relieving emotional pressure. A clever composer will manipulate this idea to more advanced structures to really toy with the listener. The composer can expand a chord sequence of “sub-dominants” and “substitutions”. ( I’d love to open that one up, but out of the scope of this already lengthy post!)
Other chords, really every aspect of music application is based off this principle, too. But its the 7th chord that carries the most power. There are some noted exceptions to this, say the major 7th, which is mostly used as a resolver. Even the almighty dominat 7th, will function sometimes as a “tonic” rather than a “dominant”; this is partially what gives Blues music such a distinct feeling. Other ways to think of this relationship between the dominant and tonic: High- Low, heavy- light, weak-strong, painful-soothing, yin-yang, etc.
Be it a jazz piano player on a corperate event, or a soulful sax player in a dive bar, all the good musicians understand this stuff, and the student is best to learn from the start.
- Leland Thunes
jazz band san francisco
