The interior of the Pisa Baptistry 
has recently been discovered to be 
the most acoustically perfect structure
in the world.


The Hoberman Iris Dome built for the
German Pavilion at EcoExpo 2000
could echo this perfection for Big Igloo.
Pisa baptistry is giant musical instrument, computers show

Rory Carroll in Rome

Thursday December 2, 1999

Italian musicologists have cracked a five century-old acoustic code to reveal that Christianity's largest baptistry is a musical instrument.

A computer analysis of the resonance inside the circular, marble structure at Pisa suggests that renaissance architects designed it to mimic the pipes of a church organ. The acoustics beneath the 75-metre cupola are so perfect that it must be either an incredible coincidence or the work of genius, scholars say.

Recordings of the walls' responses to even the faintest of noises have been processed by mathematical models to unlock the secret of how the architects used angles to manipulate sound.

Preparations are under way to perform a symphony beneath the cupola to test whether it succeeds in turning the Piazza dei Miracoli, which includes Pisa's leaning tower and cathedral, into a giant concert hall.

A successful experiment would reinforce claims that the 15th century architects who added the cupola to the baptistry built in 1152 intended to create a wonder not just of aesthetics, but acoustics.

Baptistry attendants often earn tips by singing for tourists who marvel at the echoes, but until now it was widely assumed that the acoustics were a fluke. The building was better known for a marble pulpit carved in 1260 by Nicola Pisano, the father of Giovanni.

Leonello Tarabella, a music professor at the University of Pisa, teamed up two years ago with Silvano Burgalassi, a Catholic priest who has written a book about the piazza, to investigate the acoustics.

"There is music that can exist only in this place and we intend to create it. The resonance, the vibrations, are incredible," Professor Tarabella said.

If money can be found in time the concert will be held on June 24, when the leaning tower, held up by enormous braces for seven years, is to be declared officially straightened - that is, tilting fractionally less and shored up.

On that day every year a ray of sunlight shines through a small hole in the baptistry wall and illuminates a statue of John the Baptist.


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