How a ventriloquist dummy works depends on the materials it's made from and the features it has. Traditional ventriloquist dummies have wooden or sculpted heads, jaws that drop, necks that may rotate, and eyes that may open and close. Edgar Bergen's Charlie McCarthy is a famous example of this type of ventriloquist dummy. However, soft bodied puppets may also be used for ventriloquism, such as Shari Lewis' sock style puppets, Lamb Chop and friends.
Traditional ventriloquist dummies contain a stick inside the body that supports the head and also serves as a neck. Rotating this stick turns the dummy's head. The stick also houses the controls for opening and closing the mouth and eyelids. Some dummies use string mechanisms for these functions, but more durable dummies use metal levers. Soft bodied puppets generally allow performers to control the mouth directly, by placing their fingers in the upper part of their puppets' heads and their thumbs in the jaws. Some soft bodied ventriloquist dummies may also have a lever or string for opening and closing the eyelids, or raising and lowering the eyebrows.
Most ventriloquist dummies sit on the performer's lap or a nearby table or chair, and have little movement. The performer may move one of the dummy's hands by attaching a small, discreet rod to the wrist. The performer can then move the rod with his free hand. Ventriloquists may also have assistant performers move the dummy's hands or legs with strings, similar to a marionette. This works especially well for television performances, since the assistants can easily stay out of sight.
The key to effectively using a ventriloquist dummy is, of course, for the performer to provide the puppet's voice without moving her lips. Some sounds in the English language, such as B, P, F, V, M and W require the use of the lips, so ventriloquists often substitute similar sounds and say them quickly to avoid drawing attention to them. For example, they may substitute G for B, KL for P, TH for F and V, N for M, and OOH for W. Ventriloquists may also constrict their vocal passages to minimise movement, creating the higher voice that dummies often have.
Although ventriloquists may use many vocal techniques to create the illusion that the puppet is doing the talking, most ventriloquists do move their lips at least a little bit, so part of the dummy or puppet's purpose is to distract the audience. If the audience is entertained by the performance, it will not scrutinise the ventriloquist's technique. Famed ventriloquist Edgar Bergen did many of his performances over the radio, when the main audience couldn't see the performance at all, and Muppet inventor Jim Henson found that even though he was not a ventriloquist, most people ignored him and only paid attention to the puppet when he performed live with Kermit the Frog.