Types of Triads

Triads are the basic building blocks of music harmony. Triads consist of a series of three notes separated by an interval of a major or minor 3rd. A musician must know these two intervals to build triads. A minor third spans three half steps, while a major third spans four half steps. Determining an interval requires knowledge of the chromatic scale, which consists of the following notes: C, C#(Db), D, D#(Eb), E, F, F#(Gb), G, G#(Ab), A, A#(Bb), B. The notes in parentheses are called enharmonic notes, having different names but the same pitch. For example, if you wanted a major third above D, you would count to F# instead of Gb since F# is both four half steps away from D and alphabetically three notes away.

Major

Major triads are built with a major third followed by a minor third from bottom to top. In a major scale, triads built on the 1st, 4th, and 5th scale degrees are major. Major triads often occur in music that is intended to sound consonant or free of dissonance. While all music contains a mixture of major and minor chords, the emphasis is on major chords in a major piece.

Minor

Minor triads are built with a minor third followed by a major third from bottom to top. In a major scale, triads built on the 2nd, 3rd, and 6th scale degrees are minor. Pieces written in the minor often sound spooky, scary, or sad to the listener. Bach’s “Toccata and Fugue in D Minor” is in a minor key.

Diminished

Diminished triads are constructed with two minor thirds. Only the triad built on the 7th scale degree is diminished in a major scale, so in the case of a C major scale, the B triad would be diminished. You cannot write a piece in a diminished key, as it is only a type of chord. Major and minor chords are the basis for western tonal harmony, and they are also associated with scales and keys.

Augmented

The augmented triad is built on two major thirds, which creates an unusual chord that is only found on the 3rd scale degree of the harmonic minor scale. Augmented chords rarely appear in classical music. Music is not written in an augmented key, as it is only a chord quality. A famous modern piece by Arnold Schoenberg, entitled “Pierrot Lunaire,” makes extensive use of augmented triads in the opening exposition of the composition.