The Archaeoacoustics of the Maya Pyramid of Kukulkan

On my first pilgrimage to the Maya ceremonial center of Chichen Itza in March 1995, I discovered that an incredible acoustic phenomenon can be heard at the Pyramid of Kukulkan. If you clap your hands directly in front of the pyramid's main staircase, it echoes back an almost mechanical bird-like chirping sound. Handclaps from different positions along the base of the staircase likewise trigger the echo, but with different musical tones spanning half an octave. Tour guides and tourists like to clap their hands to hear a chirped echo in a range of different notes. 

Me atop Kukulkan Pyramid in 1995

In 1998 acoustician David Lubman recorded the hand-clap echoes at Kukulkan Pyramid and compared them with recordings of the nearly extinct Quetzal, the sacred bird associated with both the name of the pyramid and its plumed serpent deity Kukulkan/Quetzalcoatl. He found that recordings and sonograms of several echoes really do match the bird's cry. Even more amazing is that same clap also seems to echo back the sound of a rattlesnake off the stairway of the nearby Temple of the Warriors a split second after the bird sound. On either side of the stairway are two stone columns four feet wide, carved to represent feathered rattlesnakes. It takes a while to find the right spot to clap to get the effect of both sounds, but it's worth it to hear that at least once in a lifetime. 

Whether the pyramid was built to deliberately produce these evocative echoes, or it happened by chance, is still a matter of debate among scientists and archaeologists. Inspection and ray acoustic modeling provide a simple physical explanation for the chirped echo -- the "picket fence effect" due to periodic sound reflections from the treads of the staircase. The reason that a chirp like a bird is produced is because of geometry. The time between later reflections is longer than early reflections causing the frequency of the echo to rapidly drop by about an octave.

Me in the Ballcourt with friends-1995

The Great Ballcourt is another structure at Chichen Itza that displays unusual and unexplained acoustic anomalies. The stone walls act like an acoustic waveguide and words softly whispered at one end of the ball court (measuring 545 feet long by 225 feet wide) are clearly audible all the way at the other end and a single clap or shout sounded in the center of the ball court will produce nine distinct echoes. According to acoustician David Lubman, "the Great Ballcourt (GBC) can produce mind-bending sound effects supportive of ancient Maya mythology described in their best-known creation story, the Popol Vuh. GBC sound effects include hallucinatory disembodied voices, shouting crowds, the whooping of an invisible bird flying rapidly through the playing field, and, with middling success, growling jaguars and menacing rattlesnakes. These animals are also represented in GBC carvings and frescoes."

Lubman's findings at Chichen Itza suggest that its ancient builders were skilled theatrical sound designers who engineered sound for mind manipulation. Sound effects discovered so far seem uniquely appropriate for each monument and may be intentional designs. If the theory of intentional design has merit, we are led to two extraordinary conjectures. The Maya may be the only people known to have "coded" a sound into stone. The chirped echo at this 1300-year-old Maya pyramid in the Yucatan may be the world's oldest known sound recording!