From: SFPhysics <SFPhysics@aol.com>
Date: Fri, 20 Mar 1998 01:37:15 EST
To: pinhole@exploratorium.edu
Subject: Re: Pinhole Daily Digest
About Geoff Ruth's sound going around corners question; yes, there is the room
reflections but:
The Huygens' Principle states that "each point of a wave front may be regarded
as a new source of disturbance". So when the sound wave approaches the corner
it needs to round there is an impedance change as it decouples from the wall
and attempts to enter the open air space. This effectively creates another
point source of the sound at the corner and the sound travels "around" the
corner to propagate in another newly expanding wave front which is not in a
straight line with the original source but may be 90 degrees from it.
I'm tired and I hope I thought this one out clearly; but, since I've been
getting more senile - take your chances on its veracity!
Al Sefl
SFPhysics@aol.com