The Wild and The Innocent (1990)

Chuck is in an institution because he is a deaf-mute, and he's learning to communicate with the world, when his sister comes to check him out and takes him to her home. She both feels sorry for being stuck in an institution, and she and her mom have a better use for the money spent on the institution. Chuck sneaks out, and starts experiencing the outdoor world, starting with a streetwalker, who takes pity on him when all he has is a sock full of change.