# Re: The Cold Voice from Book 2

news:45c101aa\$0\$28008
But when he heard Riddle's hiss, it was not in a small pipe, echoing, but
in
a big room with probably no refraction (echo?)...

Have you ever been in a really big stone or marble room? Say, like the
"rotunda" of most state capital buildings, or many museums, or traditional
cathedrals? The amount of echo and reverb is astounding. Reverb is simply
echoes piling up on themselves so fast that the original sound becomes a
blur. There is an "rt60" calculator available on the web at
http://www.trinitysoundcompany.com/rt60.html This calculates the amount of
time it takes for a sound to drop 60 decibels. If you go to that calculator
and set the material type for all the walls plus the ceiling and the floor
to "marble or tile," a 10 foot square room with a 10 foot high ceiling (that
is, a pretty small room) has an rt60 of over 8 seconds. Increase that room
size to a 20 foot square with a 20 foot high ceiling, and the rt60 is over
16 seconds. That is a lot of echo and reverb. Most modern rooms that are
built specifically to be able to have understandable speech, especially
understandable amplified speech, places like churches and theaters for live
plays, try to have rt60 of 1 and a half to 2 and a third seconds.

So the problems with a large room in a castle (with plenty of hard surfaces
like marble or stone) would not be "no refraction." The problem would be
quite the opposite; there would be so much echo and reverb that the hissing
would be quite unintelligible.

.