An acoustic raindrop effect at Chichen Itza in Mexico

One of the acoustic effects caused by the staircase of the El Castillo pyramid at Chichen Itza is the so‐called raindrop effect [Declercq et al., J. Acoust. Soc. Am. 116(6), 3328–3335 (2004)]. When visitors climb the colossal staircase of Maya pyramids, their footsteps are transformed into sound having distinct frequencies similar to raindrops falling in a bucket filled with water. In situ experiments are reported followed by numerical simulations of the raindrop effect together with a physical explanation. In addition to numerical simulations, a rule of thumb formula is extracted from the calculations that enable the prediction of the acoustic raindrop frequency at any other pyramid in Mexico. If the raindrop effect is a phenomenon that was intentionally incorporated in the construction of the Maya pyramids, such as the pyramid in Chichen Itza, then it was most probably related to the rain god Chac for which there is ubiquitous archaeological evidence decorated on the pyramid itself.