1. (n.) The act of modulating, or the state of being modulated; as, the modulation of the voice.

2. (n.) Sound modulated; melody.

3. (n.) A change of key, whether transient, or until the music becomes established in the new key; a shifting of the tonality of a piece, so that the harmonies all center upon a new keynote or tonic; the art of transition out of the original key into one nearly related, and so on, it may be, by successive changes, into a key quite remote. There are also sudden and unprepared modulations.

AM FM PM abatement about-face accommodation adaptation adjustment allayment alleviation alteration amelioration amplitude modulation apostasy arrangement assuagement betterment blunting break calming change change of heart changeableness constructive change continuity conversion damping deadening defection degeneration degenerative change demulsion deterioration deviation difference diminution discontinuity divergence diversification diversion diversity double sideband dulcification dulling easing falling-off fitting flip-flop gradual change harmonization hushing improvement inflection instrumentation intonation intonation pattern leniency lessening letdown letup lightening loosening lulling melioration mitigation modification mollification orchestration overthrow pacification palliation phrasing pitch pitch accent preparation qualification quietening quieting radical change re-creation realignment redesign reduction reform reformation relaxation remaking remission renewal reshaping resolution restructuring reversal revival revivification revolution setting shift side frequency sideband slackening softening solution soothing speech tune subduement sudden change suprasegmental suspension switch tempering tone tone painting total change tranquilization transcription transition turn turnabout upheaval variation variety violent change worsening