MODULATION (in Music) (Lat. modu/atio, from modu/nri, to regulate, from modulus, dimin utive of modus, measure, manner). '1'11e process of chamgiug from one key to another within the same composition. 111 a movement of even the smallest dimensions monotony would result if the cot»poser should confine himself strictly to one key. There are two kinds of modulations, passing and final. Passing modulation intro duces chords belonging to other keys only inci dentally and soon returns to the original key. But wInm a piece modulates so that the original key is abandoned and a new key takes its place, the modulation is final. In the sonata-form (see S(NATA) the first development of the prineilial subject confines itself only to passing nuxbila t ions. A final modulation occurs at the entranee of the secondary subject (generally to the dominant. key). The second or de velopment section is convened entirely with passing modulation. But even here the choice of keys is not arbitrary. However. no rules can be given; the artistic and :esthetic instinct of the composer is the sole guide. Ac cording to the theory of the present day, all modulation is regarded in its relation to the principal key of the piece, and, in a wider sense, all keys are but steps within the unlimited domain of tonality (q.v.). Older composers are
very sparing and careful in the use of modula tion, but those of the nineteenth century (espe cially Wagner, Schumann, Chopin) practically re moved all barriers. The means of modulation are various and cannot be discussed in an article like the present. The most frequent expedient is the different interpretations put upon the same chord. Thus the chord c, e, g may he conceived as tonic of C, dominant of F, sub dominant of G, etc., and consequently can be used to modulate at once to those keys. In modern music the chord of the diminished seventh plays an important part in modulation. Thus e, g, bb leads into D minor; the same chord conceived as e, g, bb, db into minor; as g, bb, db, fb to A flat minor; as ar., c7, e. g into B minor, etc. The principal works on modulation are: Dritseke, Antreisung ,rum kunst gerccht en M odulicren (Freienwalde, 1876) ; Riemann, II ar monie and Modulat ionsleh re (Leipzig, 1900) ; Jadassohn, Die Kunst :lc mod ulieren (Leipzig, 1890).