Acoustic wonders of Crane Mountain reproduced in backyard

Abstract

The chirping echo after a handclap in front of the stairs found in Crane Mountain and elsewhere in the world are caused by periodic structures of the stairs acting as acoustic gratings. The sound notes of specific frequencies are enhanced due to interference effect. We reproduced the fantastic acoustic phenomena found in Crane Mountain (‘chirping sound of echoing crane’ and ‘dripping on celestial staircases’) with a ‘do it yourself’ model comprising an array of wooden boards. The ‘chirping echo’ and ‘dripping’ effects are clearly audible to human ears and can be used for demonstration in schools or public performance. With this device, we also verified that the grating equation in optics can be approximately applied to predict the chirping frequencies when incident angle and diffraction angel are small.