The ninth chord , even Nonakkord , Septnonenakkord or Septnonakkord is a four- thirds of existing Five sound , the frame interval one None is. The most frequently used special form of this chord is the dominant seventh chord (sigel: D 9 ) with an additional third, whereby a major and minor ninth chord are distinguished.
Ninth chords are particularly popular in jazz. A ninth chord is often not played as a five-note chord, but only consists of a third, seventh and ninth. This means that it retains its original, sharpened sound, but with its third it ensures that it can be clearly assigned.
- Wieland Ziegenrücker: General music theory with questions and tasks for self-control. German Publishing House for Music, Leipzig 1977; Paperback edition: Wilhelm Goldmann Verlag, and Musikverlag B. Schott's Sons, Mainz 1979, ISBN 3-442-33003-3 , p. 120 f.