MODULATION, in music, the act of mov ing through the sounds in the harmony of any particular key to those of another, or the tran sition from one key to another. The simplest form is the change from a given key to one nearly related to it, namely, its fifth (domi nant), fourth (subdominant), its 'relative minor, or the relative minor of its fifth. Mod ulation into the dominant is effected by intro-' ducing in any of the parts (rarely in the bass, however) the sharp fourth, which becomes the, seventh of the new key; thus, in the key af F would be sharpened to effect the transition into the key of G; to pass from that key into• that of D it would be necessary to sharpen the C, and so on. In modulating into the subdomi, nant the flat seventh is used, which becomes the fourth of the new key; thus, in pausing .frorn the key of C to that of F, the fiat B is intro-, duced, and from the key of F to that of B the E is flattened, and so on. The modulation into
the relative minor is generally effected by em ploying the sharp fifth, which becomes the seventh or leading note of the new key; thus in changing from C to A minor the G should, be sharpened. As almost every piece ends on the key in which it begins, a second modulation becomes necessary; this is effected by flatten ing the fifth of the new key if the first modula tion is into the dominant and sharpening the fourth if in the subdominant. When a com poser aims at a striking effect he may change from some given key to one quite unrelated, from C to E for instance; but such transitions should be sparingly employed. Modulation is generally resorted to in long compositions to please the ear with a fresh succession of, chords. (See also MODE; MUSIC; TEMPERA MENT). Consult Groves, 'Dictionary of Music and Musicians) (Vol. III, pp. 232-240, New York 1910).