A word to describe a person who can change his voice at will

A mimic.

From MW dictionary:

Simple Definition of mimic : a person who copies the behavior or speech of other people

Example of mimic in a sentence: a gifted mimic who can do a terrific imitation of anyone's voice

I think the answer is IMPERSONATOR. At least that's the word I was trying to remember.. Just one of those things stuck at the tip of my tounge.. Drove me to google once more.. ..... Or IMPERSONATION ..Example: At Ten and two my friends and I do great British impersonations..

An imitator has that ability:

• a person who imitates another's voice and mannerisms for comic effect that comedian is a hilarious imitator of a surprising array of current celebrities.

(M-W)