I am in Melbourne, Australia, and we have a custom built calliope
at our Scienceworks Museum where I have been the player for that
instrument.  As to sound level, it is like a fire breathing dragon
and can be heard for miles.  It gives optimum performance on 60
pounds pressure.

While it is a great pity that some folks don't appreciate these
instruments because of the volume, there is a simple way around it
which we have used.  We have 'shaded' the sound by placing clear
Perspex sheeting along both sides of the whistles.  It takes the
extreme 'edge' off the volume.

I would think that any variation of this could be used for the
instrument in question.  Some attractive posts with clear Perspex
sheeting in between, placed around the instrument, immediately
comes to mind and would hopefully keep the neighbors happy.

John Ferguson
(Castlemaine, Victoria)

 [ Perspex and Lucite are registered trademarks for
 [ polymethylmethacrylate acrylic plastic.  -- Robbie