speaking tube

WordReference Random House Unabridged Dictionary of American English © 2026

speak′ing tube′, 

1. a tube for conveying the voice over a somewhat limited distance, as from one part of a building or ship to another.

• 1825–35

Collins Concise English Dictionary © HarperCollins Publishers::

speaking tube noun

1. a tube or pipe for conveying a person's voice from one room, area, or building to another