At the Monterey Jazz Festival this year I went over to the Coffee House on Sunday night to see Viijay Iyer Trio. I got there when they were doing sound check, so then I was able to sit in the front row directly in the middle, where I could still see Viijay playing piano.
It was a sweet show.
Before they started playing, the announcer said something that Viijay had used to describe music- he called it “mathematics in action”. I liked then, but then again, I’m in physics.
The notes in music have letters as names, but they are really based on numbers. Pitches are frequencies- which are numbers of vibrations per time.
The notes of a scale are related by numbers- 2nd, 3rd, 4th, etc.
And chords can be thought of in terms of numbers that relate to a key- the I, IV, V of the blues, the ii V7 I, and more.
Thinking in terms of numbers allows you to move music into different keys much more easily. And that lets you play what you want in more situations.