I was there too, but I thought it wasn't a valid test since there was a metal "wall" just aft of the outlet, and all sound drummed and echoed off that wall.  I have no way of quantifying the effect of that barrier but I intuit that it was substantial, so I have to pretty much ignore that test as far as sound suppression goes.  I do like the compact size and shape and hope it works out really well.
Waiting for another shoe to drop .... Jim S.

kevin lane wrote:

I was there when this prototype was first run at Tracy's.  I didn't have a decibel meter like Paul, but then I didn't need one, it was  very loud and seemed to have no muffling effect.  based on its small size and no innards, it would have been remarkable if it did have any effect, actually.Kevin Lane  Portland, OR
e-mail-> n3773@comcast.net
web-> http://home.comcast.net/~n3773
(browse w/ internet explorer)

…..also this principle is used to reduce sound effects in the exhaust outlet nozzle by routing cool air around the hot center (reduces the ripping noise quite a bit)……..fwiw. So maybe it will work on the rotary…….

 

--
Jim Sower
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T