Ventriloquism is the technique of speaking without visibly moving the lips, so the voice appears to come from a puppet or figure rather than the performer.
The vocal technique
Most speech sounds can be made with the lips still. The problem sounds are the labials — B, M, P, F, V, W — which normally require the lips to meet. Ventriloquists substitute near-identical sounds made further back in the mouth, and the audience’s ear fills in the rest because context tells them what the word must be.
The misdirection matters more than the voice
An audience looks where the character looks. A performer who keeps their own face still and neutral while the figure moves and reacts will read as silent even if their lips move slightly. Beginners overwork the voice and underwork the focus.
The evidence that character beats technique
Edgar BergenEdgar Bergen (1903–1978) was the most famous ventriloquist..., the most famous ventriloquist in American history, was a radio star. Nobody could see his lips at all. What made Charlie McCarthy work was writing and performance, not concealment.
The figure
Traditional ventriloquist dummies are hard-bodied with a mechanical head — a lever or trigger inside the body working the jawThe jaw is the lower half of a puppet's mouth — the plate ..., and often the eyes and brows. This is a different construction discipline from soft foam-and-fleece puppetry, closer to animatronicsAnimatronics is the use of motors, servos, cables and electr... More.
Contemporary practice
has moved toward soft puppets and toward openly acknowledging the performer, with acts built on the interplay between the two rather than on the illusion.
The hack: record yourself and watch with the sound off. You will see lip movement you cannot feel, and feeling is not a reliable guide.