Read Online The Sound Book: The Science of the Sonic Wonders of the World by Trevor Cox - Free Book Online Page A

out an actor’s voice. The designs exploited sound reflections, including those from the circular stage floor and scenery. All these reflections reinforced the sound of people speaking on the stage. As the Roman scholar Pliny the Elder noted, “Why are choruses less distinct when the orchestra [stage floor] is covered with straw? Is it due to the roughness that the voice, falling on a surface which is not smooth, is less united, so that it is less? . . . Just in the same way light shines more on a smooth surface because it is not interrupted by any obstruction.” 7 The straw probably quieted the sound by absorption rather than scattering. Pliny the Elder’s comments are relevant to modern homes, which have become much more reverberant, now that wooden flooring is more fashionable than carpet.
    The ancient theaters themselves provide compelling archaeological evidence of an empirical trial-and-error development of good acoustic design. 8 But there is no indication of anything like a modern scientific understanding. Writing about Vitruvius, academics Barry Blesser and Linda-Ruth Salter conclude, “Although some of his insights would be confirmed by modern science, others would prove to be nonsense.” 9 The more dubious ideas included the suggestion that a few large vases dotted around the theater would enhance an actor’s voice. 10 As a translation of Vitruvius’s writings states, “The voice, uttered from the stage as from a center, 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.” 11
    If only acoustic-engineering solutions were that cheap and easy. Unfortunately, the vases would have made little difference to the acoustic. Blow over the neck of a large beer bottle, or more fittingly a large Roman wine jug (say, 40 centimeters, or 16 inches, tall), and you might hear a low, resonant hum. This is the resonant frequency of the air enclosed within the jug. Objects have particular frequencies at which they like to vibrate; flick a champagne flute with a finger and a distinct tone is heard at the glass’s natural resonant frequency. But set a wine jug on the floor next to you at Epidaurus, and what you hear is unlikely to change. Any energy used to get the air in the jug resonating will be lost within the vessel. When you walk past empty beer bottles at a pub gig, the sound does not change.
    Intriguingly, resonant vases can be found in about 200 churches and mosques built between the eleventh and sixteenth centuries in Europe and in western Asia. These range from 20 to 50 centimeters (8–20 inches) in length, with openings between 2 and 15 centimeters (about 1–6 inches) in diameter. Unfortunately, there are no contemporaneous writings explaining their purpose. High up in the vast Süleymaniye Mosque in Istanbul, you can see a ring of sixty-four small, dark circles just below the ornate ceiling of the dome, which are openings for resonators. 12 In St. Andrew’s Church, Lyddington, UK, there are eleven jars high up in the chancel—six in the north wall and five in the south. 13 In the church of St. Nikolas in Famagusta, North Cyprus, holes can be seen that connect to hidden pots and pipes. However, scientific studies have shown they would have been useless. 14 The natural resonant frequencies of some vases do not match the frequencies of speaking or singing, and hundreds of vessels would be needed to have a significant effect.
    Such myths probably arise and persist because sound is invisible, so the cause of an aural effect is not always obvious. Before the twentieth-century advent of electronic equipment to record and analyze acoustics, it was impossible to calculate a complicated sound field such as a church. The eminent architectural acoustician Leo Beranek documented some of the myths of acoustics. 15 My