In music , a four-tone is a chord in which four different tones sound together.
The four chords that are most common in classical music are the seventh chords , which consist of three thirds layered on top of each other , i.e. adding a seventh to triads .
Other frequently used four-chords are created by adding the sixth , called the sixte ajoutée (added sixth).
In jazz music (partly also in pop music), in which four tones are considered the harmonious starting material in the specific musical architecture, there are also other variants of four tones, for example C7sus4 or C7sus2. Tredezimen chords such as G7 / 13 (quasi a tightened dominant seventh chord with additional tredezime) are often used in jazz music, but the latter chord is also known as the Chopin chord in classical music .
Other chords such as major or minor triads with an added ninth (e.g. c'-e'-g'-d '') are not considered to be four notes in the narrower sense, since according to the theory of layering thirds they are much more is about reduced five notes.