Guitar players often become frustrated when confronted with the mysterious “sus” chord in a music book. For example, while playing a song in the key of D major, a weird chord such as Dsus2 or Dsus4 pops up. Understanding and playing sus chords is very simple. Many guitar players who play by ear play sus chords all the time without knowing it.
To understand the idea of a sus chord, you must have a good grasp on major chords and scales. Chords are constructed from the notes of a particular scale. Major chords are constructed from major scales. A major scale consists of eight notes. The C major scale is C (1), D (2), E (3), F (4), G (5), A (6), B (7) and C (8). The second C is an octave above the first C. A major chord is constructed with the root note, the third and the fifth. A C major chord is C, E and G.
The term “sus” is a shorthand abbreviation for “suspended,” implying the sense of suspense or tension. A sus chord sets up a feeling of tension that leaves the listener waiting to hear a resolution. The chord is constructed by raising the third note of the chord a half-step or lowering the third note a whole step. In other words, the fourth note replaces the third, making it a sus4 chord, or the second note replaces the third, resulting in a sus2 chord. For example, in a Csus4 chord are the notes C, F and G; F replaces E. A Csus2 chord is C, D and G, with D replacing E.