Ninth

minor ninth
Inverse	major seventh
Name
Abbreviation	m9
Size
Semitones	13
Cents
12-Tone equal temperament	1300.0

major ninth
Inverse	minor seventh
Name
Other names	compound second
Abbreviation	M9
Size
Semitones	14
Cents
12-Tone equal temperament	1400.0

In music, a ninth is a compound interval consisting of an octave plus a second.

Like the second, the interval of a ninth is classified as a dissonance in common practice tonality. Since a ninth is an octave larger than a second, its sonority level is considered less dense.^[1]

^ Westergaard, Peter (1975). An Introduction to Tonal Theory, p.74. W.W. Norton. ISBN 978-0-393-09342-1.

[1] Westergaard, Peter (1975). An Introduction to Tonal Theory, p.74. W.W. Norton. ISBN 978-0-393-09342-1.

[1]