Other forms: modulations
Modulation is when you control or adjust something, like when you lower your voice to a loud whisper in order to make what you're saying more dramatic and mysterious.
The noun modulation has several meanings, including a change of key in music or of the sound of a person's voice. It almost always involves some kind of deliberate modification or slight change, like an actor adjusting his pitch or volume depending on the role he's playing or the mood of the scene. The Latin root, modulationem, has a musical meaning: "rhythm, singing and playing, or melody."