To modulate an activity or process means to alter it so that it is more suitable for a particular situation. These chemicals modulate the effect of potassium. + modulation modulations modu·la·tion The famine turned the normal modulation of climate into disaster
If you modulate your voice or a sound, you change or vary its loudness, pitch, or tone in order to create a particular effect. He carefully modulated his voice
vary the frequency, amplitude, phase, or other characteristic of (electromagnetic waves) adjust the pitch, tone, or volume of change the key of, in music; "modulate the melody