The ninth, eleventh or thirteenth tone is counted from the basic tone of the agreement.I will give the simplest possible example with the C chord in the key C (major).
The ordinary C-major chord is a so-called three-tone.It exists — which is very common for simple chords — from the first, third and fifth tone from the ground tone C. In other words, from the C, E and the G. Beyond that fifth tone, you can just count through, even beyond the octave (the eighth tone that is again a C). A C9 would therefore have to be an agreement consisting of the first, third, fifth and ninth tone or the C, E, G, and D.
The actual usual conventions in the light music, however, are slightly more complex than this.With C9, an agreement is referred to as a rule which, in addition to the aforementioned tones, also contains the lowered seventh tone. In Our example, that is the berry. This is also referred to as ‘ dominant 7 ‘ (or, in this case, ‘ dominant 9 ‘). The C9 agreement therefore consists of C, E, G, Bb, and D. Often the fifth tone (here G) in such chords (with four or more tones) is not played, and sometimes that is explicitly noted with the addition ‘ no 5th. ‘ but often not. Then the performer can choose whether or not to play the five.
If we want an agreement with a ninth tone and instead of the lowered seven, the ‘ regular ‘ seven from the scale C major (the tone B), we will note the agreement as Cmaj9.This consists of: C, E, G, B, and D.
A C agreement that skips the seventh tone, but contains the ninth, is, as a rule, listed as CADD9.So: C, E, G, and D.
And a C-chord in which the ninth tone replaces the third tone (the E), we call a Csus2 (the ninth tone is also the second tone).This agreement consists of C, D, and G.
Similar conventions also exist for the eleventh (in our example the tone F) and the thirteenth (the A) tone.In addition, Nines, elves and Dertiens can also be raised with a cross or lowered with a mole. You can therefore sometimes encounter quite complex looking states like Cmaj9/#11 (no 5th) in the wild.
First of all, the question is not correct.
The answer is very simple: it is not called so, but C9, or C13 or C11.The agreements are structured as follows:
-C7 = CEGBb (the lowered ladder own 7).
In A 9 chord is always a (lowered) 7, so
-C9 = CEGBbD
Then you also have mole 9 and cross 9
-CB9 (being Moat C7 B9) is called with a Db and C7 # 9 is with a D # The latter is also known as Mol 10.So C7b10 (is CEGBbEb). In fact, you then play a major chord with a minor at the top. This last agreement is also called the Jimmy Hendrickx agreement;-)
In a 11 chord is basically also a 7 and a 9 so
-C11 = CEGBbDF
And in a 13 chord idem, so
-C13 = CEGBbDFA
The latter agreement actually contains several agreements, namely:
C, C7, Bb, Bmaj7, DM, Dm7, Em7b5, Gm7, Gm9, Dm9, F, Fmaj7, AM, Am7 and probably even more;-)