The parallel execution of all notes of a chord is called a mixture . The chord structure can be provided with a melody, but it can also serve solely to harmonize an independent melody line. A simpler variant can be found in the Fauxbourdon or the close harmony principle, but the mixture technique occurs in all epochs and can be applied to all kinds of multi-sounds.
The term is derived from the principle of mixed voices or sound crowns in the register of an organ , which is also often referred to as a mixture . An organ always works according to the real mixture.
There are essentially three different options for executing a mixture:
- Tonal mixture : In this case, all tones in the parallel guidance are based on the tone supply of the given key . The respective intervals vary accordingly : an upward fourth often remains pure, but occasionally becomes a tritone ; a downward third appears in both major and minor forms; an initial major chord also appears as a minor and as a diminished when shifted. The examples given relate to a major-minor tonality ; however, the mixture can also occur in a piece that is based on church modes , an acoustic tonality or other tonal reserves.
- Real mixture : If the real mixture is used, all intervals remain the same. A minor sixth always remains a minor sixth in the individual transpositions, and a third fourth chord always remains a third fourth chord. Often the shift is chromatic , but it can be erratic or along a scale . It is often advisable to underlay the musical events with an organ point , not least to secure the tonal center .
- Varying mixture : This option represents a kind of mixed variant. The chord structure remains the same, but the interval relationships can be freely determined. A common tonality does not have to, but can be given. A four-tone can thus retain its original shape in the third inversion , but is arbitrarily notated as minor in one transposition and major in the other, and breaks out of its original key during the entire process. The varied mixture did not appear until the 20th century.