Yes, MODULATES is a Scrabble word!

Letter values in Scrabble US: M 3, O 1, D 2, U 1, L 1, A 1, T 1, E 1, S 1.

Is it a valid word?

MODULATES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

change the key of, in music
vary the pitch of one's speech
fix or adjust the time, amount, degree, or rate of
adjust the pitch, tone, or volume of
vary the frequency, amplitude, phase, or other characteristic of (electromagnetic waves)