MUSIC THEORY

Mod 31

• Subject of the Day:  Seventh Chords
• Reading Assignment: Textbook, pp. 41-42
• Written Assignment:  Workbook, ex. 3-2 (pp. 21+22)
• Semester Schedule

If we were to add another third on top of a triad, the result would be a seventh chord.  It gets its name from the interval from root to 7th.  So every seventh chord has a root, 3rd, 5th, and 7th.

There are many types of seventh chords, but the majority of them are of the following qualities:

Click on each chord to hear it.
 

Major seventh

The abbreviation for a major seventh chord is M7.
The M7 chord consists of a major triad and the interval of a M7 above the root (MM).
The intervals in thirds are M3, mi3, M3.

Dominant seventh

The abbreviation for a dominant seventh chord is Dom7 or Mm.
The Dom7 chord consists of a major triad and the interval of a mi7 above the root (Mm).
The intervals in thirds are M3, mi3, mi3.

Minor seventh

The abbreviation for a minor seventh chord is m7 (mi7 is used to avoid confusion).
The m7 chord consists of a minor triad and the interval of a mi7 above the root (mm).
The intervals in thirds are mi3, M3, mi3.

Half diminished seventh

The abbreviation for a half diminished seventh chord is o7 with a diagonal line thorough the o as in the graphic above.
The half o7 chord consists of a diminished triad and the interval of a mi7 above the root (om).
The intervals in thirds are mi3, mi3, M3.

Diminished seventh

The abbreviation for a diminished seventh chord is o7
The o7 chord consists of a diminished triad and the interval of a o7 above the root (oo)
The intervals in thirds are mi3, mi3, mi3

In major keys there are seven diatonic seventh chords.  These are the seventh chords that are rooted on each note of the major scale.

Click anywhere on the staff to hear all these chords.

Diatonic Seventh Chords in a Minor Key

In minor keys (because of the possibilities of either raised 7th (leading tone) or natural 7th (subtonic) and also raised 6th and natural 6th) there are 16 possible diatonic 7th chords.  (Remember, the altered 6th and 7th in minor are not chromatic tones; they are part of the key and therefore, diatonic)  Despite the 16 possibilities, the most common diatonic seventh chords are as follows:

Click anywhere on the staff to hear all these chords.

If you still have questions, contact Dr. Bartolotta at wbartolo@odu.edu.