[Aztlan] Plaster and Echoes

[Paul Troemner]

> Can someone please describe how the "chirp" is
> produced?

Greg,
This is my theory (there are other theories out there):

There are 10 near-vertical walls on the structure:  9 for the steps in the pyramid, and one at the building on top.  The chirp is made of 10 echos of the clap, each just slightly delayed from the previous echo, and slightly weaker (an increase of distance and reflecting angle and a decrease in reflective wall area as you go up the pyramid).

David Lubman says the chirp is 0.2 seconds long (I had guessed it was half second, but he had measured it).  I would guess the 10 echoes are compressed into that 0.2 seconds, which gives it a "grainier" sound than the Quetzal chirp (10 vibrations instead of 400 or some other number).  David has theorized that it is the stairs causing the chirp, but the near-vertical surface area of the stairs is smaller than the near-vertical surface area of the pyramid steps (I'll refer to stairs as the stone staircase, and steps as the 9 steps of the pyramid).  The 91 stairs may contribute part of the sound, but with smaller echoes closer together.

>From http://www.world-mysteries.com/chichen_kukulcan.htm#Statistics

The stairs' vertical area 8.85 m x 24 m, or 212 meters squared, is less than the pyramid steps' vertical area 686 meters squared (plus the building on top, 13.42 m x 6 m high on narrower side, or an additional 81 meters squared, for 767 meters squared total).

I think the stairs contribute about 1/4 of the echo effect, and the pyramid steps the other 3/4.  The pyramid steps, contributing the most, would be more likely to return a snake rattle sound from a single shake of a rattle, but this theory for the snake rattle has not been tested.  Another test would be to point a parabolic microphone at the one location at a time (5th step or 25th stair, etc.) on the pyramid during the clap and response.

I think that even if we do find out how the chirp is generated by the structure, and if we believe it was intended by the builders, how did they come up with the design?  Was it theoretical accoustic design (using the speed of sound, math, and so forth), empirical accoustic design (trial and error through earlier structures), or a combination of both?  Has anyone observed the angle a rattlesnake makes when shaking its tail?  Are the 10 cycles representative of 10 rattles on a snake, with the building on top representing the initial bead of the snake?  Are the various stepped pyramids in Palenque, Copan, and elsewhere earlier prototypes of the chirping design?

Continuing with the idea that there are potentially light and sound shows from this structure, we are aware of the snake light show, the quetzal sound show, and potentially a snake sound show.  That leaves a quetzal light show as yet undiscovered?  Why is there a rectangular building (instead of square) on top of a nearly square pyramid?

I thought I heard that the unrestored faces of the pyramid have been reported to return a similar "chirp" as the restored face of the pyramid.  If the stones or debris on the unrestored faces have at least some vertical surfaces or near-vertical surfaces, a response of some sort will be generated, but probably not as distinct as the 10-cycle echo of the restored face, and will scatter the single rattle too much to make a snake rattle return.

Paul Troemner

--- On Sat, 9/6/08, Greg Sandor <gregory_sandor at hotmail.com> wrote:

> From: Greg Sandor <gregory_sandor at hotmail.com>
> Subject: Re: [Aztlan] Plaster and Echoes
> To: "David Lubman" <dlubman at ix.netcom.com>, "D. Clark Wernecke" <CWernecke at compuserve.com>
> Cc: "Aztlan" <aztlan at lists.famsi.org>, "D. Clark Wernecke" <102402.2332 at compuserve.com>
> Date: Saturday, September 6, 2008, 12:36 AM
> Can someone please describe how the "chirp" is
> produced?
> 
> Regards,
> 
> Greg
> 
> (614) 517-7204
> greg at gregsandor.com
> http://www.gregsandor.com