Chord Types

Depending on how you think about them chords can be many things. Some basic notions and assumptions that one might come up with at first hand:

We can thus maybe say that:

In essence a chord is multiple notes sounding together.

The normal definition of a chord then imposes further restrictions on this rather free definition. Among things it usually puts the lower limit of different notes at three. Many times it is also defined as having to contain the intervals of a third and a fifth. These are however rather limiting.

Overview

Chords with only three notes (triads) none of which extending beyond the fifth, we shall call simple chords.

Chords with additions consisting of specific intervals will be called added tone chords.

Lastly, extended chords denote chords with added notes that include exotic intervals below the one being added as well.

Simple chords

To construct triadic chords using intervals below or at that of the fifth limits the possible combinations greatly, and only allows for certain possibilities:

  1. 3rd + 5th
  2. 2nd + 5th
  3. 4th + 5th

The first type make chords with minor or major tonality. Type two and three are called suspended chords.

Since the diminished and augumented chords modify the fifth degree only, they still have minor and major tonality in them. The suspended type chords however, do not since the third degree is all but replaced with a perfect interval.

Major and Minor

Using thirds as the second note in the chords and a perfect fifth as the third note, makes for chords made by stacking a minor/major third after each other:

Intervals Steps Name Notation
m3, P5 m3, M3 Minor Xm, Xmin
M3, P5 M3, m3 Major X

Diminished and augumented

Stacking a minor third on a minor third or a major third on a major third makes the fifth diminished or augumented respectively.

Intervals Steps Name Notation
m3, d5 m3, m3 Diminished Xdim, X-, X°
M3, A5 M3, M3 Augumented Xaug, X+

Suspended

Having exhausted the possibilities using thirds, we look to other intervals: seconds and fourths. These add up to a fifth

Intervals Steps Name Notation
P2, P5 P2, P4 Suspended 2nd Xsus2
P4, P5 P4, M2 Suspended 4th Xsus4, Xsus
P2, d5 P2, d4 Diminished suspended 2nd Xsus2aug?
P2, A5 P2, A4 Augumented suspended 2nd Xsus2aug?
P4, d5 P4, m2 Diminished suspended 4th Xsus4aug?
P4, A5 P4, A2 Augumented suspended 4th Xsus4aug?

Among these the only normal ons is the sus4 chord, which is often just named sus.

Some of the aug/dim sus chords emerge naturally as sus chords in the normal modal scales, but they seem exceedingly rare to me.

Added tone chords

These are like a piece of English toast: the base triad is the bread and then you just add some things on top.

Sixth chords

Intervals Steps Name Notation
M3, P5, M6 M3, m3, M2 Sixth X6, XM6
m3, P5, M6 m3, M3, M2 Minor sixth, minor major sixth Xm6, XmM6

I suppose chords with an added minor sixth are rare because of the highly dissonant minor second that occurs between the fifth and the sixth for such chords.

Added ninth chords

Xadd9, X(9)

These correspond to sus2 chords but with the second one octave up.

6/9 chord

X6/9, X6,9

The bossa nova chord.

A major triad with a major sixth and a (major)ninth (but no seventh). It is in a way a combinantion of the above mentioned sixth and ninth chords.

Extended chords

These are like “Sandwich chords” in the sense that they contain the root and the named interval; the bread around the sandwich, and the relevant intervals in between these intervals; everything in between the bread - the filling.

Seventh chords

Modifying the simple chords by adding the interval of a seventh we get the following variations:

Intervals Steps Name Notation
m3, P5, m7 m3, M3, m3 Minor seventh Xmin7, Xm7
m3, P5, M7 m3, M3, M3 Minor-major seventh Xmmaj7, XmM7, XmΔ7
M3, P5, m7 m3, M3, m3 Dominant (Major-minor) seventh X7
M3, P5, M7 M3, m3, M3 Major seventh Xmaj7,CM7, CΔ7, CΔ

In addition we can add in diminished and augumented variations into the mix:

Intervals Steps Name Notation
m3, d5, d7 m3, m3, m3 Diminished (minor) 7th Xdim7, X°7, Xm(♭7)♭5
m3, d5, m7 m3, m3, M3 Half-diminished (minor) 7th Cø, Xm(7)♭5
M3, A5, M7 M3, M3, m3 Augumented major 7th X+M7, X+Δ7, Xmaj(7)♯5
M3, A5, A7 M3, M3, M3 Augumented augumented (major) 7th not used because A7 ~ P8…

We can equivalently modify the simple suspended variations, these seem rare (?)

Intervals Steps Name Notation
P2, P5, m7 P2, P4, P4 Suspended 2nd minor 7th
P2, P5, M7 P2, P4, A4 Suspended 2nd major 7th
P4, P5, m7 P4, M2, P4 Suspended 4th minor 7th
P4, P5, M7 P4, M2, A4 Suspended 4th major 7th
m3, d5, m7 m3, m3, d4 Diminished (minor) 7th
m3, d5, M7 m3, m3, P4 Diminished major 7th
M3, A5, m7 M3, M3, A4 Augumented minor 7th
M3, A5, M7 M3, M3, AA4 Augumented major 7th

Adding sevenths to the normal diatonic chords taken from the modal scales one gets:

Ninth chords (High seconds)

Eleventh chords (High fourths)

Thirteen chords (High sixths)

A note on Eight, Tenth, Twelwth and Fourteenth chords

These are uncommon not because the numbers bring bad luck but rather because the equivalent intervals one octave down are already present in a normal extended chord:

Due to these equivalences these chords would contain several repetitions and thus not add tension to the chord.