Tonal response on the stairway of the main pyramid at La Ciudadela, Teotihuacan archaeological site

This paper presents new research on the very interesting audible effects produced by the stairways of many archaeological sites in Mexico. This investigation was made at the main stairway of the pyramid at La Ciudadela, Teotihuacan archaeological site. The effect previously studied was a chirped echo reflected from the stairway at normal incidence, which resembles the singing of the Quetzal. Now it is presented with the impulsive sound source and the listeners located at different angles, where apart from the characteristic chirped sound, several musical notes could be obtained and identified, covering a range of at least one half an octave. This evaluation was made at the site, where the effect is clearly audible, and it is supported with simple mathematics.