Maritime Use
Voice pipes, the maritime term, served to transmit reports from lookout positions aloft to the deck and from the bridge to the steering position and engine room. These were somewhat larger in diameter than the domestic version and were often covered in sound absorbent material to increase their efficiency. About 1780, one captain removed a canvas voice pipe installed by an imaginative midshipman saying he was sure the topmen would “use it for an improper purpose”.
One disadvantage of voice pipes is that they may breach the integrity of watertight spaces. This led to the introduction of shut-off valves on both ends of voicepipes to prevent water from a flooded compartment from entering other compartments via its voicepipes.
Permanently fitted, rigid voice pipes are still in use and are generally covered with heavy lids to avoid ingress of water. The speaker has to place the mouth in the "horn" or bell-shaped end of the pipe and the receiver has to 'bend an ear' to hear what is being said.
Voice pipes have generally been replaced by sound powered telephones. Even on modern ships, however, they may still be found linking wheelhouse and binnacle for communication of magnetic compass heading to the helmsman in the event of a blackout.
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