A triad is a three-note chord (or, more generally, any set of three notes, pitches, or tones). There are four kinds of triads: |
| Triad | Root | 3rd | 5th |
|---|---|---|---|
| Major | 1 | 3 | 5 |
| Minor | 1 | b3 | 5 |
| Augmented | 1 | 3 | #5 |
| Diminished | 1 | b3 | b5 |
| The major is very consonant; the minor is a bit less so but still consonant for most purposes. The augmented is very dissonant and the diminished is extremely dissonant as it contains a tritone (augmented fourth or, in this case, diminished fifth). The major and minor triads may have their fifth omitted, although this is uncommon. If the third of a major or minor chord is omitted, the result is a fifth chord, which is often called a power chord when played on an overdriven guitar. Triads and Inversions If we look at a C major triad or three-voice chord it is based on combining a root voice (C) with two other voices at slightly different intervals of a third (E, a major third from C and G, a minor third from E). If we compare the key of C major to the C major chord using the names do, re, mi, fa, sol, la, si, to represent the scale degrees 1, 2, 3, 4, 5, 6, 7, the C major chord is constructed from the notes do, mi, and sol. This same relationship is true for all major triads in all corresponding major keys. Building a C Major Triad: |
| Note | Degree | Name |
|---|---|---|
| C | 1 | do |
| D | 2 | re |
| E | 3 | mi |
| F | 4 | fa |
| G | 5 | sol |
If we juxtapose these three notes (the root, major third and perfect fifth) they can be structured or 'voiced', C-E-G, E-G-C or G-C-E. No matter what order the three notes (called voices) are in they still create a C major chord. It does not matter if the voices are the singers in a choir or the instruments of an orchestra, if the notes are all either C, E, or G we simply have a gigantic sounding C chord. The two consecutive intervals produced by these voicings would be: C E G = major third, minor third (root position) If the root (C) is on the bottom this voicing is called root position. If the third (E) is on the bottom it is called first inversion. If the fifth (G) is on the bottom this voicing of the triad is called second inversion. Since there are only three possible voicings of a triad it is relatively easy to hear them in that they are a common feature of the past two centuries of traditional harmonic structures in Western music. The use of the exponentially more complex voicings arising from 4-voice, 5-voice and larger chords is more challenging. Some 4-voice chords are used in traditional, 'classical' and church music but others such as the diminished seventh were strictly forbidden in early sacred music as they contained the tritone interval; the mathematical halfway point in the octave which allegedly sounded Satanic. Other 4-voice chords were not used in symphonic and 'classical' music until the French Impressionist era and in modern jazz. All triads and 4-voice chords are built within the octave, or eight-note scale which encompasses the do-re-mi-fa-sol-la-ti-do of the major scale, for instance, or the scale steps 1-2-3-4-5-6-7-8; eight being the octave where the pattern starts over again. All triadic and therefore, common, chords can be constructed the same way : using the 1 3 5 formula. Take the C scale, for instance : Building Harmonizing Chords in the Scale of C Major |
| Degree 1 2 3 4 5 | Chord Name | 1-3-5 Triad | Rel. Name |
|---|---|---|---|
| C D E F G | C Major | C E G | I |
| D E F G A | D Minor | D F A | iim |
E F G A B | E Minor | E G B | iiim |
F G A B C | F Major | F A C | IV |
G A B C D | G Major | G B D | V |
A B C D E | A Minor | A C E | vim |
B C D E F | B Diminished | B D F | viidim |
This works for any scale, and whether the chord formed is minor or major depends on the scale: the I, IV, V chords are major, and the rest are minor, with the seventh being diminished. |
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