If I play the chord: GBDA, then this is considered a Gadd9. But if I play the 3rd above the 5th (GDB), it is not called a 10th.
Why don't we refer to all notes by 1-7, and is there a system to picking higher numbers (11) vs lower ones (4)?
The distinction is between interval distances (2nd -> ∞) and chord tones (root, 3rd, 5th, 7th, 9th, 11th, 13th).
When you play Gadd9, you are adding the chord tone that is a 9th above the root. If we just played a G9 chord, the dominant 7th would actually be implied (G-B-D-F-A).
Playing the interval of a 10th above the root (like G-D-B) doesn't change the chord. All that does is displace the chord tone (in this case, the 3rd) up one octave, so it's still called a G major triad.
So, a note would be described as a fourth if we were talking about interval distances, and an 11th if it was a chord tone (typically preceded by the root, 3rd, 5th, 7th, and 9th).
The exceptions are sus chords and 6 chords. A sus chord would typically have a 2nd or 4th above the root suspended in the middle of a triad voicing, often substituting for the third (like C-D-G or C-F-G). A 6 chord substitutes the 5th of the chord with a 6th, but maintains the same function of the original chord.
These numbers come from the figured bass system of composition and performance, wherein roman numeral symbols (
When you see something that says
Essentially the number is there to let you know what octave to play the dissonant note (7th, 9th, 11th). In a G major chord, 4 would most likely be referring to playing a C above the B but below the D, while 11 would suggest playing C above the D.
Don't agree with NReilingh's definition of a 6 chord. Generally a 6 chord is spelled 1, 3, 5, 6.Thus GBDE is G6.The 11 chord is usually made from 1, 3, 5, b7,11. So using a '4' and a b7 makes 11.Just like a '2' and a b7 makes a 9. G11 will be GBDFand C - a sort of dominant 7 sus 4.