Music Theory Basics
Naming the notes
Start out with do-re-me: the notes of the diatonic scale are the notes that are used in the European musical tradition. Think of these as the white notes on the piano. The seven notes of do-re-me represent a neat mathematical relationship. All sounds are made of frequencies of vibrating air that hit you ear and stimulate little hairs that send messages to you brain. The cool thing about the ear is that it can recognize when sounds have certain mathematical relationships. Without going into the actual relationship, the notes of the diatonic scale have common denominators so that to the human ear, they have similar or compatible sounds.
The diatonic, or major scale is made up of notes that sound right together and the basis of this is mathematics. (Did you ever noticed that musicians usually do good in the Math SAT's, yet seem to be losers otherwise?)
The diatonic scale is not based on any key. It is mathematical relationship between notes. Each note has it's own number starting with the Roman numeral I and going to VII. The I note in the key of C is C and the II is D. The I note in the key of G is G and the II is A. C is related to D in the key of C as G is related to A in the key of G. They are the same note - only the key is different.
Harp players "get" this, because they change harps for each key. Harp players don't have to do fancy mathematics to figure where the sharps and flats are, because they always play the same notes, they just vary the key.
The basic chords are Triads, or three notes. We add color an interest by varying this, but the basic chord is: three notes together in a pattern of every other note. A Major chord is I, III and V. The mathematics of this arrangement makes it a very pleasant combination of notes. This major chord is the building block of all European music. If you choose the II, IV, and VI notes then you get a minor chord. Aristotle and his homies spent a lot of time working out all the combinations and naming them.
Note: Actually, when you take into account all the sharps and flats which make up the half steps the interval is not every other note, but from the first note, go up four half steps and then three half steps. This is way too confusing to conceptualize, but if I don't mention it, I will get mail from experts explaining just where I screwed up.
The big leap here, for the harp player, is to jump from thinking of holes to thinking of the Roman numeral numbers of the diatonic scale. This jump is not hard. Most of you are already there. The blues is I, IV, V and you've been thinking in those terms for a while.
Three Little Chords
Each triad is named after it's starting note. So the I chord starts at the I note. The IV chord starts at the IV note and the V chord starts at the V note. After that it goes up every other note (see caveat above).
The I chord is called the Tonic, the IV chord is the Subdominant and the V chord is called the Dominant. There are other chords with neat names like Mediant and Supertonic, but we don't concern ourselves with them. Us blues guys use the three main chords. There's a joke: How do you teach a Swing musician to play blues? Take away a chord. How do you teach a Jazz musician to play blues? Take away 437 chords. How do you teach a rock star to play blues? I don't know.
I've laid out the basic blues progression in another section (Picking up Blues Harp). If you don't know the I-IV-I-V-IV-I progression then you should review this section and listen to blues a little until it becomes natural to you. I usually spend a session or two in my blues harp class playing blues with the class and getting them to hear the changes from chord to chord. It's OK to understand the blues progression, but you should be able to hear it. It should be natural to you and the only way to do this is to listen to blues.
How does this relate to the Diatonic Harmonica?
The harmonica was made in Germany to play German folk music. I am told that Oom-pah bands are still called Harmonicas in Germany. Blow-Draw, Blow-Draw is oom-pah, oom-pah. This is the I-V chord combination. The harmonic plays a I chord on the Blow and a V chord on a blow. In cross-position the Draw is the I and the blow is the IV. This is the magic of mathematics.
The blow notes in a C harp are C, E and G. This is a triad and happens to be the C chord. The draw notes are G, B, D and F. This is called a G7dim chord. (there's an A there, but it doesn't help us much, cross harp players don't play that 6 hole much.). We know that the G is the V chord because if we count up from the C: C, D, E, F, and G, that's 5 notes. So if C is the I then G is V. If we start the counting from G, the way we do in cross harp, then it's G, A, B, C to get to C. Notice that there are only 7 notes and that after the G we have to start over again with A. If we start with G as the I then C is the IV.
Circle of Fifths
Theory books make a big deal about the circle of fifths. If you start at C and go up 5 the next key is G. 5 more notes and the next is D and then 5 more is A, etc. Our three blues chords are the I, IV and V. The V is the next chord in the circle of fifths and the IV chord is the chord previous to I in the circle.
Blues harp players use the circle of fifths to name the position. If we play a C harp in the key of C then we are in First position. If we play G on a C harp then we've gone up on the circle of fifths and we are playing second position. If we go up to the next position (another 5 steps) then we are in D and you know that playing D on a C harp is third position. Some people can play 4th and higher and 12th is not supposed to be that bad, but they don't sound all that great. The only one I ever heard do the higher positions well is Howard Levy and it's well know that he wasn't even born on this planet.