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
to vary the amplitude, frequency, or phase of a carrier wave, usually to transmit information
fix or adjust the time, amount, degree, or rate of; "regulate the temperature"; "modulate the pitch"
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