A speaking tube or voicepipe is a device based on two cones connected by an air pipe through which speech can be transmitted over an extended distance.

Use of pipes was suggested by Francis Bacon in the New Atlantis (1672). The usage for telecommunications was experimented and proposed for administrative communications in 1782 by the French monk Dom Gauthey in a memorandum communicated to the Académie des Sciences. Dom Gauthey launched a subscription supported by Benjamin Franklin and other French scientists to finance further experiments, but was not able to raise enough money to go ahead. The British utilitarist philosopher Jeremy Bentham proposed the inclusion of "conversation tubes" in the architecture of his Panopticon (1787, 1791, 1811) and then as a means of military telecommunication (1793) and at the end as a necessary equipment in the architecture of ministries (1825).

While its most common use was in intra-ship communications, the principle was also used in affluent homes and offices of the 19th century, as well as expensive automobiles, military aircraft, and even locomotives. For most purposes, the device was outmoded by the telephone and its widespread adoption.