modulate

verb4

1. •
   To regulate, adjust or adapt.
2. •
   To change the pitch, intensity or tone of one's voice or of a musical instrument.

   • "Can you tell?" she asked, in a trembling but well modulated and sensual voice. — 1980
3. •
   To vary the amplitude, frequency or phase of a carrier wave in proportion to the amplitude etc of a source wave (such as speech or music).
4. •
   To move from one key or tonality to another, especially by using a chord progression.