Acoustic traps
The corrugations on the surface of
the seats act as natural acoustic traps. Though this effect would seem to also
remove the low frequencies from the actors' voices, listeners actually fill in
the missing portion of the audio spectrum through a phenomenon known as virtual
pitch. The human brain reconstructs the missing frequencies, producing the
virtual pitch phenomenon, as in listening to someone speaking on a telephone
with no low end.
The findings are detailed in the
April issue of the Journal of the Acoustics Society of America.
Amazingly, the Greek builders of the
theater did not themselves understand the principles that led to the
exceptional audibility of sound from the stage.
Attempts to recreate the Epidaurus
design never quite matched the original. Later seating arrangements featured
other materials, such as wood for the benches, an approach which may have
ultimately derailed the design duplication effort.
