D defs.my
Entry 4 senses Webster, 1913

Modulation

/mäjˌ-əl-āsh'-ən/ · Mod·u·la·tion · IPA /ˌmɑd͡ʒəˈleɪʃən/
01 n. The act of modulating, or the state of being modulated; as, the modulation of the voice.
  1. 1.
    The act of modulating, or the state of being modulated; as, the modulation of the voice.
  2. 2.
    Sound modulated; melody.[R.]
  3. 3.
    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.(Mus.)
  4. 4.
    The alteration of hte amplitude, intensity, frequency, or phase (of the carrier wave of a radio signal) at intervals, so as to represent information to be transmitted.(Electronics)