Yes, TREMOLO is a Scrabble word!

Letter values in Scrabble US: T 1, R 1, E 1, M 3, O 1, L 1, O 1.

Is it a valid word?

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

(music) a tremulous effect produced by rapid repetition of a single tone or rapid alternation of two tones
vocal vibrato especially an excessive or poorly controlled one