Speaking Trumpet

an instrument with a spreading, somewhat funnel-shaped lip, used by a fire chief, or an officer at sea, in order that his commands may be heard above the tumult. When the speaker places the small end at his lips and shouts an order, the trumpet prevents the waves of sound from spreading, and directs them in a sort of sheaf to the spot toward which the trumpet is pointed. In this way the whole force of the speaker's voice, though scarce heard elsewhere, is concentrated in one line of sound. Acting on the same principle the speaking tube used in houses and in offices, especially in communicating from one floor to another, is exceedingly serviceable in its place; but a tube of uniform diameter cannot be made to carry sound to a point distant from its extremity. See Sound