Ventriloquism

Gabbo and his ventriloquist dummy Otto in The Great Gabbo (1929)

Ventriloquism or ventriloquy is an act of stagecraft in which a person (a ventriloquist) speaks in such a way that it looks like their voice is coming from a different location, usually through a puppet known as a "dummy". The act of ventriloquism is ventriloquizing, and in English it is commonly called the ability to "throw" one's voice.