Pyramid echo 'mimics sacred bird'

Ancient Mayans designed their pyramids to echo like the call of a sacred bird, a researcher told the meeting of the Acoustic Society of America this week. Archaeologists had previously dismissed the sound effects as design faults.

Sharp sounds made inside the Mayan pyramid at Chichen Itza in eastern Mexico echo as a series of chirps. When David Lubman, an acoustics consultant based in Westminster, California, visited the pyramid in January, he saw a limestone staircase that he assumed was responsible for the effect. He simulated the echo produced by such a staircase using a computer model and found that it matched that produced in the pyramid.

Dr Lubman also heard the cries of the resplendent quetzal, a beautiful green bird revered by the Mayans. He obtained recordings of the bird's cry, identified its notes and compared them with the pyramid's echo, finding close similarities between the two.

The ancient Mayans were perfectly capable of the simple engineering required to create this effect, Dr Lubman argued. "If the hypothesis of intentional design is true, the chirped echo may be the world's oldest sound recording," he said.

* Acoustic Society of America