or music theory
is the note
nine scale degrees
from the root
(counting the root itself) and also the interval
between the root and the ninth. as would occur between the first and transposed second degrees
of a major scale
In tonal music of common practice, the interval of a ninth is heard as a dissonance. A ninth is a compound second, but the ninth is considered less dissonant than the second.
A ninth chord or dominant ninth is a chord or dominant chord with a ninth, and as an extended chord typically includes the seventh along with the basic triad structure. Thus, a Cmaj9 consists of C E G B and D . When the symbol "9" is not preceded by the word "major" or "maj", the implied seventh is a minor seventh -- e.g. a C9 consists of C E G Bb and D .
Added tone chords with what might be called an added second are usually said to have an added ninth, two fifths up from the root.
The Hendrix chord uses a sharpened ninth. This is, enharmonically, the flatted third, and is tonally ambiguous or bitonal.
The Minor Ninth chord is played with a flattened third and 7th the formula is 1, b3, 5, b7, 9. This chord is wrote as Cm9. This chord has a more "bluesy" sound and fits very well with the dominant 9th.