THE unique acoustics of ancient monuments around the world are facing destruction, claim researchers pushing for legislation to protect the echo-rich qualities of prehistoric sites. 快猫短视频s meeting at the First Pan-American/Iberian Meeting on Acoustics in Canc煤n, Mexico, this week are making the plea as they highlight the importance of acoustics in sites from painted caves to pyramids.
Rock art expert Steven Waller says the acoustics of ancient sites reveal much about the people who built them. Waller and others have taken sound recordings of echoes around 150 different archaeological sites. He told the conference that at many sites, including Horseshoe Canyon in Utah and Hieroglyphic Canyon in Arizona, the echoes are more intense at points where decorations appear than elsewhere around the site.
Waller believes the eerie natural sound effects may have been a primary motivation for some of the paintings. 鈥淧eople are so used to echoes now as invisible sound waves propagating back that we鈥檝e forgotten what it was like before we knew that,鈥� he told 快猫短视频. 鈥淭hey used to think it was spirits speaking back to them.鈥�
Advertisement
In a separate presentation, acoustic consultant David Lubman described his research on the Mayan site at Chich茅n Itz谩 in Mexico. In 1998, Lubman suggested that the Mayans designed the staircase of the main pyramid at Chich茅n Itz谩 so that its echo sounded like the chirp of the quetzal, the sacred bird shown with the mythical figure Kukulk谩n, to whom the site is dedicated (快猫短视频, 10 October 1998, p 7). Now Lubman has created a computer model of the steps that recreates how the echoes would have sounded before the monument鈥檚 surface began to crumble. 鈥淧eople will be able to hear what the ancients heard when the pyramids were new,鈥� he says.
Such sound effects provide valuable insights into the purpose of a site, says Umashankar Manthravadi of Indiana University of Pennsylvania. He has measured the acoustics around an elaborate two-storey structure carved out of the rock near Bhubaneswar in India over 2000 years ago. The Archaeological Survey of India says that it was a place set aside for meditation, but Manthravadi thinks the acoustic properties of the ground-floor platform reveal it was a theatre. His measurements show that a person speaking anywhere on the 鈥渟tage鈥� area can be heard loudly throughout the site, but not if they move as little as a metre away. Of all the ancient excavations in India, only two have been tentatively identified as theatres, says Manthravadi. He suggests acoustical techniques could perhaps reveal many more.
Waller says special acoustics remain largely unrecognised by archaeologists and government agencies, and warns that at many sites, ancient sound effects are being lost through erosion, vandalism, noise pollution and alterations to sites. He cites the prehistoric cave at Rouffignac in France, which has an electric train inside to shuttle tourists around, and Fremont Indian State Park in Utah, where a visitor centre in the middle of the canyon interferes with echoes. At Petroglyph National Monument in Albuquerque, a planned four-lane highway is likely to mask any natural sound effects.
The American Rock Art Association is currently drafting guidelines for managers of archaeological sites that will include advice on conserving acoustics. But Waller and his colleagues are calling for the UN, the archaeological community and tourist agencies to develop 鈥渁coustic standards鈥�. Says Waller: 鈥淭here are penalties if someone came up and spray-painted [over] art, but there鈥檚 no penalty for the counterpart in acoustics.鈥�