He primarily communicates through telepathy and the manipulation of people's minds. He uses fear and suggestion to control the townspeople and even affects their dreams. While he can technically speak, he chooses to use these more subtle forms of communication to better control his victims.
However, there are instances where Tak's thoughts are described as sounding like "a rasping voice", "a whispering voice", or "a howling voice". This indicates that he has the capacity to speak, but he primarily chooses not to.