Archaeological acoustic study of chirped echo from the Mayan pyramid at Chichén Itzá

Abstract

Handclaps evoke impressive chirped echoes from the unusually narrow limestone staircases of the Mayan pyramid at Chichén Itzá, located in Mexico’s northern Yucatan. This highly conspicuous acoustical feature, apparently ignored in the archaeological literature, may provide important clues to Mayan cultural practices of the time. Inspection and ray acoustic modeling provide a simple physical explanation for the chirped echo—the ‘‘picket fence effect’’ due to periodic sound reflections from staircases. The authors argue that chirped echoes were always present, and are not spurious artifacts of reconstruction. It is suggested that the Maya must have noticed and may have exploited his acoustical feature in ceremonies at their sacred site. Is the chirped echo an acoustical design flaw, or intentional acoustical engineering by a perceptive stone age people? The author suggests that the simple acoustical engineering required for intentional design falls well within Mayan capabilities. In seeking a cultural motivation for intentional design, it is speculated that the chirped echo may be intended to imitate the primary call of the Mayan sacred bird, the resplendent quetzal. Recorded sound samples show that the two sounds do bear uncanny resemblance. The quetzal hypothesis also provides a credible explanation for the unusually short staircase treads.