Chord Construction : 5) Intervals and Chords
Bernard McDonagh

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All chords come from scales; from the Major scale yes, but also from other scales. Some are Minor scales, and the diminished scale, and whole-tone scale are other examples.

Even though chords can be formed from various scales, all of the reference points for identifying chords, and in fact for music theory generally, relate back to the Major scale. By this, I mean that even in something quite removed from the major scale, the diminished scale for example, we still refer to the major scale for the means to categorize and name everything.

Each note below is named firstly in terms of it's distance from the root (the name we give it as an ‘interval'). Secondly, we see what quality or harmonic characteristic it will bring to any chord formed from that root. ( i.e. The name it has when it is part of a chord.) The example root here is C.

Let's take a brief example or two using the above information. In the key of C Major, an ‘A' note will most often be called a 6th, but at other times it would be called a 13th; depending on other notes present in the chord. The next article in this series will address these things.

The basic triad at the heart of most chords will of course take first consideration in naming chords. These are of course the root, 3rd and 5th. So for example, if a chord with a C root has an E in it, then this major 3rd will take priority over an Eb or D# that may also be present in the chord. The Eb or D# will then be considered a #9.

The distance from C to G# is an interval of an ‘augmented fifth', but if a G# or an Ab was a part of any C chord, we'd call either of them a #5. However, if there was a perfect 5th (G) already in the chord, then b13 would be the correct name for a G# or an Ab also present .

Some areas are open to debate. If there was a Gb or F# present, and an Ab or G#, then you'd have to decide whether one was b5 (Gb ) and the other was a b13 (Ab ), or whether one was a #11 (F#) and the other a #5 (G#). Confusing? Well, it can be difficult to decide at times.

Here's another example. The interval from C to D b is a semitone, or a ‘Minor Second'. But if a Db , or a C#, were a part of any chord with C as the root, we'd call it a ‘ b9' (Flat 9). As always, each of these examples applies universally, and not just when we talk about ‘C' chords.

Note: Even though this table is quite comprehensive, there are other intervals not named here. There are, for example, intervals that are theoretically possible, such as a diminished 2nd, i.e. C to D bb . Now we know that ‘D double flat' is quite theoretical, and that it is known as just a ‘C' the overwhelming majority of the time. It is unnecessary then, to list the Diminished 2nd, 3rd, 6th intervals here. They are rare as melodic intervals in music, and are never used where harmony and chords are concerned.

* The diminished 7th interval listed above is the one case when a diminished interval is also used as diminished in chord construction. It is the same in pitch as a 6th or 13th, and would in all other cases be thought of that way, but in the case of the diminished 7th chord this note is in fact a diminished 7th, and not a 6th or 13th.

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© 2004 Bernard McDonagh
Email : author@gsus.biz
http://www.gsus.biz

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