Al's Music Tidbits - Volume 5
by Al Shank
Last week I promised you chords, and chords ye shall have; but, first, there’s another fact about intervals we should cover. We have been illustrating intervals as one note above another, c to g being a perfect fifth, etc. However, we can also, and will, talk about a note some interval below another note. When we turn an interval upside down, we call it “inverted”, and there are rules, of course, for inverting intervals. The inversion of interval n is (9 – n), so if we invert a fifth we get a fourth, if we invert a sixth we get a third, etc. This is easy, but also remember that all the intervals come in different sizes, depending on the number of semitones between the notes. Here are some rules:
- the “perfect” intervals (unison, octave, fourth and fifth) stay “perfect” upon inversion
- the “major” intervals (second, third, sixth, seventh) become “minor” on inversion, and vice versa
- the “diminished” intervals (fifth, rarely seventh) become “augmented’ on inversion, and vice versa
The important thing about this is that the dominant note of a key (the fifth degree, remember?) can be found a perfect fifth above the tonic, or a perfect fourth below. The subdominant is a perfect fourth above or a perfect fifth below. The major third degree is also a minor sixth below the tonic, etc.
The combination of two or more harmonic (vertical) intervals makes a chord. In our Western music, including Bluegrass, chords are normally formed by superposing (stacking) thirds. If we take our major scale, select the tonic note and skip one, we come to the note a major third above the tonic (c to e, for example). If we stack another third on top of the third degree, we get the fifth degree (e to g). So now we’ve got a triad, built on the tonic, containing the tonic, the 3rd and the 5th. The intervals are:
tonic to third – major 3rd
third to fifth - minor 3rd
tonic to fifth - perfect 5th
So, you are actually hearing three intervals, which make up the “tonic triad”. I generally use arabic numbers for the notes of a scale and Roman numerals for the chords. So,:
I = 1, 3, 5 (c e g in the key of C)
We call the note upon which we are building the chord the “root” of the chord, the other two the “third” and “fifth”, for obvious reasons.
We can construct a chord on each degree of the scale in the same manner, getting:
II = 2, 4, 6 (d f a)
III = 3, 5, 7 (e g b)
IV = 4, 6, 1 (8 is the same as 1) (f a c)
V = 5, 7, 2 (9 is the same as 2) (g b d)
VI = 6, 1, 3 (10 is the same as 3) (a c e)
VII = 7, 2, 4 (11 is the same as 4) (b d f)
If you play these chords on your “Bluegrass piano”, you will notice that they do not all sound the same; besides, of course, being at different pitch levels, they have different “flavors”. You might perceive some of them as “sad”, others as “happy” and one of them sounds dissonant, although this is very subjective. The reason they sound different is because those pesky half-steps between scale degrees fall in different places, which creates different intervals between the root and the other chord tones. If the third above the root is a major third, we call the chord a “major triad”, made up of a major third and a perfect fifth over the root. If this first interval is a minor third, we call the triad “minor”, made up of a minor third and perfect fifth above the root. In this chord, the interval between the 3rd and 5th is a major third. So, we have:
Major triads I IV V
root to third – major 3rd
third to fifth - minor 3rd
root to fifth - perfect 5th
Minor triads II III VI
root to third – minor 3rd
third to fifth - major 3rd
root to fifth - perfect 5th
That leaves the triad on the 7th degree, which is the only one built from the major scale that has two minor thirds stacked up, yielding what is called a “diminished” triad; the fifth between the root and 5th is a diminished fifth. This chord is rarely, if ever, used in Bluegrass, but sounds like a dominant seventh chord, which is used all the time and about which we will learn more next month.
The harmony used in most Bluegrass, Country and folk songs is pretty simple, consisting of the tonic, subdominant and dominant chords, or I, IV and V in our numbering system. If you learn your intervals, you can easily find those chords, and their notes, in any key, since they are always based on the tonic, the note a perfect fourth above the tonic and the note a perfect fifth above it, and they are all major triads, consisting of a major third and a perfect fifth above the root.
We go back to our chromatic scale and the “shape” of our major scale:
c c# d d# e f f# g g# a a# b c c# d d# e f f# g g# a a# b c
db eb gb ab bb db eb gb ab bb
1 – 2 – 34 – 5 – 6 – 71
Let’s pick the key of G, which is probably the most popular key in Bluegrass. For the tonic triad, we need a major third above g; remember that a major third is 4 semitones, so g to g# to a to a# to b. Next, we need a minor third (3 semitones) above the b, so b to c to c# to d. So g b and d make the tonic triad. The IV chord is built on the 4th degree, a perfect fourth above the tonic, or 5 semitones; if 4 semitones above g is b, then 5 must be c. Now we have the root of the IV chord, and we build the triad the same way, 4 semitones above c is e, and 3 above e is g, giving us c e and g for the IV chord.
See whether you can construct the V chord for yourself. Answer next week, along with more about chords.
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