(Fr. ‘fugue’, Ger. ‘Fuge’, It. ‘fuga’).
Type of contrapuntal comp. for particular no. of parts or ‘voices’ (described thus whether vocal or instr., e.g. fugue in 4 parts, fugue in 3 vv.). The point of fugue is that the vv. enter successively in imitation of each other, the 1st v. entering with a short melody or phrase known as the subject (different from sonata‐form ‘subject’ in that it is merely melodic and short). When all the vv. have entered, the exposition is over. Then (normally) there comes an episode or passage of connective tissue (usually a development of something that has appeared in the exposition) leading to another entry or series of entries of the subject, and so on until the end of the piece, entries and episodes alternating.
Contrasts of key constitute an important element in fugal construction. In the exposition the subject first appears, naturally, in the tonic key; the 2nd v. to enter with it does so a 5th higher (or 4th lower), i.e. in the dominant key, the name answer now being attached to it; the 3rd is a repetition of the subject (in a higher or lower octave) and so on, subject and answer, tonic and dominant keys, thus appearing alternately, according to the no. of ‘voices’ engaged. One function of the episodes is to effect modulation to various related keys, so that the later entries may have the advantage of this variety, but once the exposition is over it is not considered necessary that further series of entries shall always alternate as to keys in the subject‐answer manner.
In addition to the subject there is often a counter‐subject appearing in the exposition and probably later in the fugue. It is of the nature of a melodic acc. to the answer and subject (generally in double counterpoint). The v. which has just given out the subject or answer then goes on to the countersubject whilst the next v. is giving out the answer or subject and so on.
Sometimes in later entries there is overlapping of the subject, each v., as it gives out, not waiting for the previous v. to finish it but breaking in, as it were, prematurely. This device, which is called stretto, tends to increase the emotional tension of the entry in which it occurs.
Occasionally, after the exposition (and possibly before the 1st episode) there is a counter‐exposition, much like the 1st exposition in that the same 2 keys are employed. Appearances of the subject (in the exposition or elsewhere) are sometimes separated by something of the nature of the episode, but shorter, called a codetta.
The exist 2 types of fugue with 2 subjects (or double fugue), one in which the 2 subjects appear together from the outset, and another in which the 1st subject is treated for a certain time, the other then appearing and being likewise treated, after which both are combined. In choral fugues (e.g. in an oratorio movement) there is sometimes a free instr. part, an accompanied fugue. The device of pedal is often employed in fugue, especially near its close.