Which Chord is it, add 9, or sus 9?
The difference between an “add 9” chord and a “suspended 9” (sus2) chord lies in their composition and the specific intervals they include from the root note. Here’s a breakdown of each:
Add 9 Chord
An “add 9” chord includes the root, major third, perfect fifth, and the added ninth note of the scale. It does not omit any note that would be in a basic major or minor chord but adds the second note of the scale an octave up (the ninth) to the triad. This results in a chord that has a rich, full sound with a bit of brightness or tension from the ninth. The formula for an “add 9” chord is:
- Major Add 9: 1 – 3 – 5 – 9
- Minor Add 9: 1 – ♭3 – 5 – 9
For example, a Cadd9 chord would include the notes C (root), E (major third), G (perfect fifth), and D (ninth).
Suspended 9 (Sus2) Chord
A “suspended 9” chord, more commonly referred to as a sus2 chord, replaces the third of a chord with the second (or ninth) note of the scale, effectively suspending the chord between a major and minor quality by omitting the third, which determines a chord’s major or minor quality. The formula for a sus2 chord is:
- Sus2: 1 – 2 (or 9) – 5
For example, a Csus2 chord would include the notes C (root), D (second/ninth), and G (perfect fifth).
Key Differences
- Third vs. Second: The major difference is the presence of the third in an “add 9” chord, retaining the chord’s major or minor quality, versus its replacement with the second (or ninth) note in a sus2 chord, creating an open, unresolved sound.
- Chord Quality: “Add 9” chords have a defined major or minor quality because they include the third. Sus2 chords, lacking the third, do not have this defined quality and instead have a more open, airy feel.
- Function and Use: “Add 9” chords are often used for their rich, extended sound, while sus2 chords are used for their ambiguous, unresolved quality, often resolving back to a major or minor chord or used for a specific textural effect in a progression.
Both types of chords add texture and interest to chord progressions and melodies in various musical contexts.