Three Notes Is A Chord
When three different notes are sounding simultaneously they create the first instance of a chord. Chords can have many more than just three notes, but I would argue that they may have no less than three. Two notes is afterall an interval, is it not?
An interval can sometimes imply a chord, as when an artist creates the expectation musically of a particular chord but then only gives the two notes that define that chord most characteristically. The artist would be fulfilling most of the expectation of the listener, relying on cultural precedent to do the rest of the work filling in the missing tones.
So, there are lots chord combinations. To count them we have to think about the smallest interval, involving two different notes (the half-step). Then we need to count a half-step on top of another half-step as our first chord. A half-step with a whole-step on top of it would be our second chord. We’re “stacking” intervals here, to create chords. A half-step with a minor-third on top of it would be the fourth chord. But keep in mind that we have to exclude the unison and octave intervals as they are just a repeat of a note. Remember, a chord is defined as three different notes sounding simultaneously. That leaves eleven different intervals that can be stacked on top of eleven intervals, which makes 121 possible two interval chord combinations within each key. Multiplied by 12 keys, the number of possible two interval chord combinations jumps to 1,452. Remember also that chords can be composed of many more than three notes. For instance, if we consider all four-note combinations in the same manner there are 15,972 possibilities. Five note chords are very common. There are 175,692 possible combinations of 5 note chords.
Thank God there are a relatively small number of chords that are much more commonly used than the others. It helps also to name them in some systematic way. They’re much easier to reference in your memory once categorized.
There are four main types of triads. “Triad” is just another name for a three-note chord.
The four types are…
diminished
minor
major
augmented
A diminished chord is made by stacking two minor-third intervals. So diminished chords have the closest/smallest intervals of the four types.
An augmented chord is made of two major-thirds, stacked. It has the largest, or most largely separated, intervals of the four types.
Major and minor are easy to remember simply because a major-chord is a major-third with a minor-third stacked on top, conversely a minor-chord is a minor-third with a major-third stacked on top.
We’re only working with major and minor-thirds, stacking them in every permutation, and systematically naming discrete instances of chords when they appear.
There are only four possibilites for stacking major and minor-thirds.
minor-third, minor-third – diminished triad
minor-third, major-third – minor triad
major-third, minor-third – major triad
major-third, major-third – augmented triad
You could of course apply this process to all of types of intervals: seconds, fourths, fifths, sixths, sevenths. But seconds are too small, and sound very dissonant when played in triads…to most Western listeners. Fourths are pretty good, but a little too far apart. Chords in fourths are useful in certain musical situations, but used in excess fourths leave the music sounding empty. Our ears can discern notes at and above a fourth interval discretely a little too easily. Thirds are the happy medium.
So these triads in thirds are the basis for almost any chord you’ll see in common use.
For instance, an A-major triad is simply a major triad whose root note is an A. Likewise, an C-minor chord would be a minor triad whose root is C. In the triads we’ve been discussing thus far the root has always been the lowest note of the chord. However this will not always be the case, as when the intervals within a chord are inverted.
The root of the chord is the note in the chord against which all the others are compared. In theory, every note of a chord could be considered as the root, but the precedents of our musical culture create a situation where considering one chord tone over another as the root makes much more sense.
The notes comprising a chord are called “chord tones.” It is also common to distinguish these chord tones from one another by what interval separates each note in the chord from the root.
For instance, it’s common to talk about the 1, 3, and 5 of a chord. The 1 refers to the root. The first note in the chord, and a unison away from itself. The 3 is the second note in the chord, but it’s a third away from the 1. Similarly, the 5 is a fifth away from the root.
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