At this research point I was asked to chose one or two of Bach’s Fugues or Inventions, which I should analyse in terms of contrapuntal diversions and add to my listening log.
Those four diversions mentioned in my study folder are:
- Imitation : Which is either a modification or the exact repetition of a motif.
- Inversion: Is usually the reflection of the intervals from a motif.
- Augmentation: Describes the expansions of note values
- Diminution: Describes the reduction of note values
From my own musical experience I also know, that there are a few more ways to diverse a theme. Those especially developed in the 20th century through Arnold Schönberg’s 12-tone-technique, but having played and analysed a few of Bach’s Preludes and Fugues already, I noticed that diversions like that where used in the period of the Renaissance.
- Retrograde : Is a motif being played backwards
- Retrograde-inversion : A mixture from the two points mentioned above, which describes a motif that is being played backwards with reflected intervals
- Stretto : (close; thight) : A start of a new imitation of a motif before the motif that was played before is ended.
From my former studies also already learned, that a fugue is always a polyphonic piece, which usually has either three or four voices. The amount of voices stays the same throughout the whole piece. Furthermore, a fugue is mono-thematic, which means, that there is only one single theme which is being repeated in varied ways. ( There are a few exceptions, where a fugue has more than one theme). The parts of the piece, where the theme doesn’t appear is called “episodes”, they often even contain short motives of the theme. The parts of the piece which include the main theme are called subject presentations.
A fugue always has the same structure. It is basically compound by only subject presentations and episodes (which usually have a modulating use). Only the first thematic development has to follow certain rules: At the beginning of a fugue (the very first thematic development), the theme has to be played once in every voice. The first note of the theme alternates between the tonic and the dominant. After the first theme (also called “Dux”), which is only played by the first voice, is finished, the second voice starts playing the theme (called “Comes“) on the dominant 5th. During this variation of the first theme, the first voice continues with a contrapuntal theme. (1)
As mentioned above, the second voice (Comes) starts the theme on the dominant. For this entrance there are two possibilities : The real answer and the tonal answer. The real answer occurs when the intervals of the first theme (dux) are kept the same. The (more often used) tonal answer, stays in the same key signature.
- Heukäufer, N.(2014). Musik Abi – Kompaktwissen Oberstufe. Berlin: Cornelsen Scriptor, p. 107-108