mod·u·late / ˈmäjəˌlāt/ • v. [tr.] exert a modifying or controlling influence on: the state attempts to modulate private business's cash flow. ∎  vary the strength, tone, or pitch of (one's voice): we all modulate our voice by hearing it. ∎  alter the amplitude or frequency of (an electromagnetic wave or other oscillation) in accordance with the variations of a second signal, typically one of a lower frequency: radio waves are modulated to carry the analog information of the voice. ∎  [intr.] Mus. change from one key to another: the first half of the melody, modulating from E minor to G. ∎  [intr.] (modulate into) change from one form or condition into (another): ideals and opinions are not modulated into authoritative journalese.DERIVATIVES: mod·u·la·tion / ˌmäjəˈlāshən/ n.mod·u·la·tor / -ˌlātər/ n.

modulation. The changing from one key to another in the course of a section of a comp. by evolutionary mus. means (not just by stopping and starting anew in another key) and as a part of the work's formal organization. The simplest and most natural modulations are to the related keys (or attendant keys) i.e. to the relative minor or major, to the dominant and its relative major or minor and to the subdominant and its relative minor or major. The tonic major and minor are also related keys, modulation from one to the other being simple, but they are not usually so described. Chromatic modulation, found frequently in Wagner, Franck, and Strauss, in general means altering a chord by means of a chromatic change. It can also be achieved by moving basses up or down major or minor 3rds. Enharmonic modulation covers the use of chords altered by enharmonic means, e.g. turning a dominant 7th chord to a Ger. 6th. Modulation becomes less of a feature in atonal mus. because of the enlargement of the scale. First composers to use modulation may have been Obrecht and Desprès. Chromatic modulation occurs in madrigals of Gesualdo and Monteverdi. John Bull's organ fantasia Ut, re, mi, fa, sol, la modulates a whole tone upward successively into different keys. With J. S. Bach, modulation became integral part of fugue.

modulate † make melody XVI; regulate, adjust; attune XVII; pass from one key to another XVIII. f. pp. stem of L. modulārī measure, adjust to rhythm, make melody, f. modulus (dim. of modus MODE); see -ATE2.
So modulation XIV. — L. module XVI. — F. or L.