腹语术，是一个腹语表演者借由练习使得其口部看似完全没有动作来发出声音的戏剧表演。腹语术的表演方式就是用口技发出声音。实际上腹语仍旧是用声带发音，只不过腹语师借由练习而产生不是由腹语师发出声音的错觉。 腹语术在古代曾被利用为声称拥有超自然能力的人表现其神力的工具，但不免被戳破，如《清稗类钞．方伎类．肚仙召福仔》中凌福篯问肚仙能否背诵出其子生前所读过的文章而直接揭穿巫者的骗局。九世纪时君士坦丁堡普世牧首Photios认为这是藏匿在人腹中的魔鬼且只配居住在粪坑中。

腹语表演的原理是将嘴唇的动作降到最小，某些不可避免的嘴型动作则必须改以接近的小嘴型发音来做替代如以舌尖中音替代双唇音。常见的腹语表演是腹语师搭配人偶，进行一段逗趣对话，多是表演性质而较少古代常见的魔术性质。

Ventriloquism, or ventriloquy, is an act of stagecraft in which a person (a ventriloquist) changes his or her voice so that it appears that the voice is coming from elsewhere, usually a puppeteered "dummy". The act of ventriloquism is ventriloquizing, and the ability to do so is commonly called in English the ability to "throw" one's voice.