Examples from the Web for mouthpiece
In both cases, when someone answered he was to blow three times into the mouthpiece, and then hang up.
Three short breaths into the mouthpiece, and the line went dead.
In her glowing description of stone throwing, she crosses the line of objectivity, becoming a mouthpiece rather than a reporter.
“The idea was patently absurd that the show was a mouthpiece for any point of view,” he said.
For a second, I wondered if Specter himself was on the line, covering the mouthpiece with his hand.
Yet John Keats is in some respects out of keeping with the magnificent phraseology of which he is the mouthpiece.A Day with Keats|May (Clarissa Gillington) Byron
On one side of the mouthpiece was the mark of a right thumb, and on the other those of a first and second finger.The Pit Prop Syndicate|Freeman Wills Crofts
Mildmay took it, and, inserting the small tube in his ear, spoke into the mouthpiece.With Airship and Submarine|Harry Collingwood
The thread on the end of the stem for the mouthpiece is formed by a special machine.Tobacco Leaves|W. A. Brennan
Trent decided immediately that Da-yak, the Tibetan, was of no consequence, merely a mouthpiece.Caravans By Night|Harry Hervey
British Dictionary definitions for mouthpiece
Word Origin and History for mouthpiece
also mouth-piece, 1680s, "casting fitted on an open end of a pipe, etc.," from mouth (n.) + piece (n.). Meaning "piece of a musical instrument that goes in the mouth" is from 1776. Sense of "one who speaks on behalf of others" is from 1805; in the specific sense of "lawyer" it is first found 1857.