Chords and their names
A chord is three or more notes sounding together. Most chords in the music you know are built the same way: start on a note, the root, and stack thirds on it, skipping every other note of the scale. C, skip D, E, skip F, G: the chord of C.
This chapter goes through the chords, how their names are written, and how Ferrous Lineup names what it hears.
Triads
Three notes stacked in thirds make a triad: the root, the third above it and the fifth above that. A third is either major (four semitones) or minor (three), so there are four ways to stack two of them:
| Triad | Thirds, from the bottom | On C | Written | Sounds |
|---|---|---|---|---|
| Major | major, then minor | C E G | C | bright, settled |
| Minor | minor, then major | C E♭ G | Cm | darker, still settled |
| Diminished | minor, then minor | C E♭ G♭ | Cdim, C° | tense, wants to move |
| Augmented | major, then major | C E G♯ | Caug, C+ | unsettled, floating |
Major and minor triads have a perfect fifth between root and fifth (seven semitones). The diminished triad squeezes it to six, a tritone; the augmented one stretches it to eight.
A key gives each of its notes a triad from its own notes. In a major key they come out major on the 1st, 4th and 5th notes, minor on the 2nd, 3rd and 6th, and diminished on the 7th: C, Dm, Em, F, G, Am, Bdim in C major. In harmonic minor, the raised seventh gives an augmented triad on the 3rd note too:
To hear them, open the piano roll, pick Draw > Chord in key (triad), and click a note: it draws the triad the key gives that note. The chord buttons above the grid play each one.
Suspended chords
A sus chord leaves the third out and puts the note next to it in its place: Csus4 is C F G, Csus2 is C D G. With no third it is neither major nor minor, and the fourth of a sus4 pulls down to the third: Csus4 to C is one of the oldest sounds of a cadence.
Seventh chords
Stack one more third, and the chord gets a seventh above the root. Jazz and most popular music use sevenths all the time:
| Chord | Notes on C | Written | Where it lives |
|---|---|---|---|
| Major seventh | C E G B | Cmaj7, CM7, CΔ | on the 1st and 4th notes of a major key: soft, dreamy |
| Dominant seventh | C E G B♭ | C7 | on the 5th note of a key (G7 in C): pulls home |
| Minor seventh | C E♭ G B♭ | Cm7, C-7 | on the 2nd, 3rd and 6th notes of a major key |
| Half-diminished | C E♭ G♭ B♭ | Cm7♭5, Cø | on the 7th note of a major key, the 2nd of a minor one |
| Diminished seventh | C E♭ G♭ B♭♭ (A) | Cdim7, C°7 | on the raised 7th note of a minor key |
| Minor-major seventh | C E♭ G B | Cm(maj7) | on the 1st note of harmonic minor |
The dominant seventh is called that because it is the chord on the dominant, the fifth note of the key. Its third and seventh (B and F in G7) are a tritone apart and want to move by a semitone each, to C and E: that pull is why G7 leads to C. What chords do explains it.
Two sixth chords add a sixth instead of a seventh: C6 (C E G A) and Cm6 (C E♭ G A).
Ninths, elevenths and thirteenths
Stacking further thirds gives the ninth (the second, an octave up), the eleventh (the fourth) and the thirteenth (the sixth):
| Written | Notes on C | |
|---|---|---|
| C9 | C E G B♭ D | a dominant seventh with a ninth |
| Cmaj9, Cm9 | C E G B D, C E♭ G B♭ D | the major and minor sevenths with a ninth |
| Cadd9 | C E G D | a triad with a ninth, but no seventh |
| C6/9 | C E G A D | a sixth with a ninth: a bright ending in jazz |
| C7♭9, C7♯9 | C E G B♭ D♭, C E G B♭ D♯ | altered dominants, sharper still |
| C11, Cm11 | C E G B♭ D F, C E♭ G B♭ D F | with an eleventh |
| C13, Cmaj13 | C E G B♭ D A, C E G B D A | with a thirteenth |
Players rarely play all of these notes: they leave out the fifth, and in a thirteenth chord the eleventh, which clashes with the third (the app’s C13 has no eleventh either).
Writing chord names
A chord name is the root and a few letters for its kind. Musicians write the same chord in several ways, and Ferrous Lineup reads them all; it writes each back in one way:
| Kind | Ferrous Lineup writes | Also reads |
|---|---|---|
| major | C | Cmaj, CM |
| minor | Cm | Cmin, Cmi, C- |
| diminished | Cdim | C°, Co |
| augmented | Caug | C+ |
| suspended | Csus4, Csus2 | Csus |
| major seventh | Cmaj7 | CM7, Cma7, CΔ, CΔ7 |
| minor seventh | Cm7 | Cmin7, Cmi7, C-7 |
| half-diminished | Cm7b5 | Cø, Cø7, C-7b5 |
| diminished seventh | Cdim7 | C°7, Co7 |
| minor-major seventh | Cm(maj7) | CmM7, C-maj7, CmΔ7 |
| augmented seventh | C7#5 | C7+5, C+7, Caug7 |
| six-nine | C6/9 | C69 |
Sharps and flats in a name are typed with # and b: F#m7, Bb13. A
name is case-sensitive where it matters: CM7 is a major seventh,
Cm7 a minor seventh.
Slash chords and inversions
A chord’s notes can be stacked in any order. The note at the bottom, the bass, changes how it sounds:
- with the root at the bottom, the chord is in root position: C E G;
- with the third at the bottom, it is in first inversion: E G C;
- with the fifth at the bottom, second inversion: G C E;
- a seventh chord has a third inversion, with the seventh at the bottom.
A chord name shows the bass after a slash: C/E is C major with E in the bass, and G7/F is G7 in third inversion. When the note after the slash is not in the chord, as in F/G, it is a chord over a bass note, a sound of its own (F/G is a softer way to play G11).
The Roman numerals under the chords show inversions as classical harmony does, with the numbers of figured bass: I⁶ for a first inversion, I⁶₄ for a second, and V⁶₅, V⁴₃ and V⁴₂ for the inversions of a seventh chord.
In the piano roll, the list next to Draw picks the inversion of the chords you draw (Root position, 1st inversion and so on), and Tools > Invert chords up or down turns the chords you already have. Inversions make a smoother bass line: C, G/B, Am, G steps down the scale instead of jumping.
Two chords at once
An orchestra can play two chords at once, one over the other: a polychord. Ferrous Lineup writes it with the upper chord first and a bar between them. The chord that opens Stravinsky’s Augurs of Spring, which the strings hammer for pages, is E♭7|F♭: E♭7 above, F♭ major below.
Type a polychord on the chord sheet the same way: Eb7|Fb.
How the app hears chords
The piano roll names chords in two rows over the grid: the chord the channel plays, and under it, on All, the chord all the channels make together. The chord sheet, the harmony keys and Write the chords the song plays name them the same way.
The app listens as a musician does, over a stretch of music rather than note by note:
- an arpeggio, a chord played one note at a time, is heard as its chord;
- a tune counts for less than the chords under it, so a melody note passing over C doesn’t turn it into Cadd9;
- a bass note between two chords counts as a passing note, so a walking bass doesn’t change the chord on every beat;
- where no chord name fits, as in much music of the 20th century, the notes are named as a pitch-class set instead (see Beyond keys: sets, rows and micromodes).
Pointing at a step tells you more, as in “Am: A minor, chord vi of C major”: the chord, its full name, and what it does in the key.