I finally got around to building the 3-1/2-octave bottle organ
that I previously posted questions about on the this Digest.  I have
come across a rather puzzling phenomenon.  At first it appeared that
the sound dispersion from one bottle sounding was not uniform.  In
other words, at some locations in the listening room the volume was
very loud.  In another location just a few feet away the volume was
very low.

At first I assumed the effect was related to the sound map generated
by the air blowing across the bottle.  After I moved the organ to
various locations in the listening room I discovered that the
non-uniformity seemed to have little to do with the organ location
but rather to do with the room itself.  One location in the room has
the lowest perceived volume irrespective of where in the room the
organ is located.

I am puzzled that this is such a dramatic effect.  Is it possible
that this very severe non-uniformity is related to that fact that
the sound from the bottle blow is almost a pure sine wave with very
few harmonics?  My hope is that when the organ is actually playing
the effect will not be too noticeable.  I would appreciate any comments
or suggestions.

Phil Dayson
Vancouver, British Columbia, Canada