Harmonic function: tonic, subdominant, and dominant chords

Harmonic function is the job a chord does in a key: the tonic rests, the subdominant prepares a move, and the dominant leads back to the tonic. In C major those chords are C, F, and G; in A minor they are Am, Dm, and E or E7.

The tonic in C major

The tonic in C major is C, spelled C E G. Play C and stop on it.

Am and Em can take that resting role for a bar. Am is A C E, so it shares C and E with C E G. Em is E G B, so it shares E and G with C E G. Play C, Am, C. The middle chord keeps C and E, and the return supplies G. Play C, Em, C. The middle chord keeps E and G, and the return supplies C.

The subdominant and the other preparation chord

The subdominant in C major is F, spelled F A C. Play C, F, C and stop on the second C. That cadence is plagal, IV to I: F A C returns to C E G.

Dm, spelled D F A, prepares the dominant. Play C, Dm, G, C. F does this same job in C, F, G, C, where F A C moves to G B D. Dm and F are predominant chords.

The dominant in C major

The dominant is G, spelled G B D. B is a half step under C. Play G, then C, and let B rise to C. G7 adds F, spelled G B D F. On the way into Cmaj7 (C E G B), F falls to E and B rises to C. Play G7, Cmaj7 and listen for both of those half steps at once.

Bdim, spelled B D F, is the leading-tone triad. Play B D F, then C E G, with B moving to C, D to E, and F to G.

Four cadences in C major

An authentic cadence is dominant to tonic. Play C, F, G, C and stop on the last C. The last two chords are G (G B D) into C (C E G).

A plagal cadence skips the dominant. Play C, F, C and stop on the second C. The move is F A C into C E G.

A half cadence ends on the dominant. Play C, F, G and stop on G (G B D). B is a half step under C, and you stop before B goes to C.

A deceptive cadence sends the dominant to Am. Play C, F, G, Am. B still rises to C, and C is the third of Am (A C E), so the landing chord is vi.

D7 is the dominant of G, labeled V of V, and it fits inside a C major phrase. D7 is D F# A C. F# sits outside the C major scale C D E F G A B. Play D7, G. F# rises to G, and C falls to B, the third of G (G B D). Then play G7, C: B rises to C, and F falls to E.

Tonic, subdominant, and dominant in A minor

A natural minor uses A, B, C, D, E, F, G. The triads on those notes are Am (A C E), Bdim (B D F), C (C E G), Dm (D F A), Em (E G B), F (F A C), and G (G B D).

The tonic is Am, A C E. The subdominant is Dm, D F A. Play Am, Dm, Am. That is a plagal cadence in minor, iv to i. F in Dm falls to E in Am.

Em, spelled E G B, is the dominant you get when the seventh stays G. G is a whole step under A. Play Am, Em, Am and listen to G moving up a whole step to A.

Raise G to G# and the dominant is E, spelled E G# B, or E7, spelled E G# B D. G# is a half step under A. Play Am, E7, Am. G# rises to A, and D, the seventh of E7, falls to C, the third of Am. G#dim, spelled G# B D, uses that same G#: play G#dim, Am and G# rises to A.

Preparation and the other landing chords in A minor

Bdim, spelled B D F, is degree 2 in natural minor. The half-diminished seventh on that degree is Bm7b5, spelled B D F A. It prepares E7. Play Am, Bm7b5, E7, Am. F in Bm7b5 steps down to E, the root of E7.

C, spelled C E G, is III, the relative major of A minor. Play Am, F, C and hold C for a bar. F is VI, spelled F A C. Follow C with E7, Am and G# rises to A.

A deceptive cadence in A minor sends E7 to F. Play Am, Dm, E7, F. G# rises to A, and A is the third of F (F A C), so the dominant lands on VI.

G, spelled G B D, is VII, the triad on the unraised seventh. Play Am, G, Am, then play Am, E7, Am. In the first pair, G moves to A by a whole step. In the second, G# moves to A by a half step.

Match the numerals to what you hear

In Cymasphere, set the key, drag the chords from PALETTE onto the progression timeline, and switch the block display format to numeral. Numeral display shows Roman numerals: match C to I, F to IV, and G to V. In A minor, match Am to i, Dm to iv, and E or E7 to V. Letter display shows the chord name. Use it to check that the dominant reads E or E7, then play E G# B or E G# B D. Solfege display names the degrees Do, Re, Mi, Fa, Sol, La, and Ti.

Generate Progression can bias a draft toward harmonic functions before you label the blocks. Build that draft from the chord progression generator, then walk the timeline with the numeral display on.

Fm in a C major phrase is F Ab C. Play C, Fm, C and Ab falls a half step to G in C E G. Ab, Bb, and Eb, and the chord each one moves to, are in borrowed chords.

Play the minor cadence, then connect the notes

Put Am, Dm, E7, Am on the timeline, one bar each, and listen for G# in E7 (E G# B D) rising to A. Then open voice leading and play B in G7 rising to C in Cmaj7, a half step into the tonic the way G# rises to A.