Recently, I’ve been playing with music-filtering software and hardware — like the superbly cool Filter Factory by Electrix. Then I read this cool piece on Nature.com, in which acousticians have analyzed Mayan tombs and found that they were designed to produce incredibly weird sound effects. If you stand in front of the staircase of the El Castillo pyramid and clap your hands, you’ll hear an echo that sounds like the chirp of a bird. If you walk up the stone steps, it produces a flurry of echoes that sounds like rain falling into a bucket. As Nature reports:

Declercq’s team has shown that the height and spacing of the pyramid’s steps creates like an acoustic filter that emphasizes some sound frequencies while suppressing others. But more detailed calculations of the acoustics shows that the echo is also influenced by other, more complex factors, such as the mix of frequencies of the sound source.

Since the Mayans were hardcore mathematicians, it’s entirely possible they did this stuff intentionally, though Declerq and his team won’t know until they do more measurements.

(Thanks to SciTech Daily for this one!)