Vitruvius Quote

On this principle of arrangement, the voice, uttered from the stage as from a centre, and spreading and striking against the cavities of the different vessels, as it comes in contact with them, will be increased in clearness of sound, and will wake an harmonious note in unison with itself.

Chapter V, Sec. 3 - De architectura (The Ten Books On Architecture) (~ 15BC) - Book V