Vitruvius, in his work De Architectura, argued that the most suitable places to build theatres were “consonant”, i.e. places where the voice, from below, increases in volume as it rises upwards, supported by the shapes of the structure. When this was not enough, however, there were some tricks that helped to amplify the sound: for example, it was common to place upside down bronze vases in special cells between the seats of the audience, which acted as amplifiers.
