Note: This discussion started on Alt.Sci.Physics.Acoustics Newsgroup and was forwarded to acoustic-ecology discussion group. Some additional comments
have been collected by email.
At least two structures at the Mayan ruins of Chichen Itza in Mexican display unusual and unexplained acoustical properties.
The Great Ballcourt:
The Great Ballcourt is 545 feet long and 225 feet wide overall. It has no vault, no continuity between the walls and is totally open to the sky.
Each end has a raised "temple" area. A whisper from end can be heard clearly at the other end 500 feet away and through the length and breath of the
court. The sound waves are unaffected by wind direction or time of day/night. Archaeologists engaged in the reconstruction noted that the sound
transmission became stronger and clearer as they proceeded. In 1931 Leopold Stokowski spent 4 days at the site to determine the acoustic principals
that could be applied to an open-air concert theater he was designing.
Stokowski failed to learn the secret.
The Castillo:
This structure is a temple that looks like a pyramid and is the one most commonly pictured on travel brochures for the Mexican Yucatan. Apparently if
you stand facing the foot of the temple and shout the echo comes back as a piercing shriek. Also, a person standing on the top step can speak in a
normal voice and be heard by those at ground level for some distance. This quality is also shared by another Mayan pyramid at Tikal.
I believe a good case can be made that the Maya somehow engineered these acoustical phenomena. After months of research, I cannot locate any
scientific discussion or investigations regarding any of this. Any information or comments appreciated.
Wayne Van Kirk
[email protected]
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-Response-
I was at Chichen Itza two years ago. These acoustic phenomena are fascinating. The idea that they were intentionally engineered is not implausible,
but it seems clear that it would have been different than our definition of 'engineering' in the modern world.
It is really cool though and I would enjoy knowing more about it if people can add to the discussion.
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-Response-
There are other "undocumented" acoustical properties of the ruins. When I was there several years ago the guide showed me a stack of what looked
like stone artillery shells. He said that to this day no one has been able to determine what they were for. Then with a wink he picked up two sticks
and proceeded to play a tune on the "shells". Each one was precisely tuned. Perhaps the "ancients" knew more about acoustics than we give them
credit for.
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-Response from reposting on acoustic-ecology discussion group -
A similar phenomenon to that reported at the Mayan ballpark structure can be experienced in Vancouver. At Science World two parabolic dishes have been
set up across a large open noisy room. One can speak softly into one and the sound can be easily heard at the other end. I'm sure the two are not
identical but the concept is the same and there is quite a bit of novelty appeal. The dishes are about 300 feet apart and have approx. a four foot
radius. The effect only works when one speaks at or listens from the focal point of each dish which is not consistent with the report from Mexico,
however, it might be a starting point into thinking about how it works.
I also heard a similar phenomenon during last year's Vancouver Folk Music Festival. I work at the Jericho Sailing Centre about 1/4 mile due west of
the westernmost edge of the festival site. between the sailing centre and the site is a small hill, large enough to block out a good deal of the
ruckus (except of course for the low frequencies). The west wall of the centre is about 35 feet high and about 60 feet long, it's surface is stucco
and glass. Standing in front of it, I could hear perfectly the performances from one of the westernmost stages of the festival.
My theory (and this is just plain speculation, no math involved here) is that the wall is high enough to reflect the sound that was being blocked by
the hill. The stucco provided enough surfaces at the right angle to bounce the sound down. It could have also been bent down around the hill, by a
temperature inversion or some other atmospheric or geographical factor but that theory breaks down because the sound was quite clear only in front of
the wall. Clarity also varied at different distances and positions in front of the wall.
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-Response-
I think you are awfully lucky to be able to go to the wonderful Vancouver Folk Festival whenever you like. ;-)
Seriously, there's also Michelangelo's dome in St Peter's/Rome. A whisper from the dome can be heard in the church. I believe there are some
humorous stories associated with this particular phenomenon.
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-Response-
RE: The Castillo:
The 'piercing shriek' sounds like it originates from some sort of periodic structure. Is the Castillo covered with stone steps? A similar effect
occurs when you clap your hands near an iron fence or corrugated wall, and the impulse is returned from each corrugation. The echo then sounds like a
'twang.'
The acoustic ducting effect is something else again. Might a periodic structure on the building surface act to diffract the waves and make them follow
the surface?
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[Edited on 6-12-2002 by Toltec]