In 1998, Lubman published a Journal of the Acoustical Society of America study suggesting that when someone claps in front of the ” El Castillo” pyramid at the famous site of Chichen Itza in Mexico’s Yucatan, a chirp echo results that sounds like the song of a quetzal bird. Subsequent studies supported the idea, and gave rise to hordes of tourists now clapping away in front of the famous monument, once a temple to the feathered snake god, Kukulkan.
The secret to the echo, a “pee-yooh” noise, as Lubman describes it, lies in the famously tall and narrow steps adorning the front of Maya temples. Unlike the echo you hear from shouting at the straight walls of a canyon, the tall steps on the pyramids tune the noise returned through an effect called “Bragg scattering,” each riser bouncing back small echoes that add together to create a distinctive chirp.
A 2004 report in the same journal, led by Nico Declercq of Belgium’s Ghent University, supported the idea, and also found an explanation for another acoustic effect, where listeners seated on the bottom steps of the pyramid heard raindrop sounds generated by people’s footsteps farther up the 100-foot-high temple pyramid. Both the quetzal and rain were sacred to the Maya, Declercq and colleagues noted, “probably due to the fact that Mayans originally lived for many centuries in the forest before getting involved in the construction of cities and religious sites.”