Consecutive Fifths

In music, consecutive fifths, or parallel fifths, are progressions in which the interval of a perfect fifth is followed by a different perfect fifth between the same two musical parts (or voices): for example, from C to D in one part along with G to A in a higher part. Intervening octaves are irrelevant to this aspect of musical grammar; for example, parallel twelfths (i.e., as created by successive intervals of an octave plus a fifth) are equivalent to parallel fifths.

Though used in, and evocative of, various kinds of popular, folk, and medieval music, parallel motion in perfect consonances (P1, P5, P8) is strictly forbidden in species counterpoint instruction (1725–present) and during the common practice period, consecutive fifths were strongly discouraged. This was primarily due to the notion of voice leading in tonal music, in which, "one of the basic goals...is to maintain the relative independence of the individual parts." A common theory is that the presence of the 3rd harmonic of the overtone series influenced the creation of the prohibition.