mod·u·la·tion 
(mŏj′ə-lāshən)
(mŏj′ə-lāshən)n.
1. The act or process of modulating.
2. The state of being modulated.
3. Music
a. A passing or transition from one key or tonality to another.
b. The result of such a transition.
4.
a. A change in stress, pitch, loudness, or tone of the voice; an inflection of the voice.
b. An instance of such a change or an inflection.
5. The harmonious use of language, as in poetry or prose.
6. Electronics The variation of a property of an electromagnetic wave or signal, such as its amplitude, frequency, or phase.