1. 改变，调节(嗓音或声音)
If you modulate your voice or a sound, you change or vary its loudness, pitch, or tone in order to create a particular effect.

1. vary the frequency, amplitude, phase, or other characteristic of (electromagnetic waves)

2. adjust the pitch, tone, or volume of

3. fix or adjust the time, amount, degree, or rate of

e.g. regulate the temperature
modulate the pitch

Synonym: regulate

4. vary the pitch of one's speech

Synonym: toneinflect

5. change the key of, in music

e.g. modulate the melody