Noise Solutions: "Ninety at nine feet"
Cheech, something that has been left out is that a dB measurement on the ground at 9 ft does not depict how much sound is heard in flight.
Before the war starts here, I fly both Pattern and IMAC. As well as Ducted fans and Sport.
There are a number of variables involved. Do you point the dB meter at the fuse, prop or at a degree away from the plane. Then you have temp, humidity etc.
The pattern standard is 96dBs at 9 feet with the dB meter pointed 45degrees to the fuse to the front. Most people agree that pattern planes are extremely quiet in the air, and actually a flame out can't be detected with a 40 size sportplane in the air.
IMAC has worked hard to come up with an intelligent solution for measuring sound. Props, exhaust deflection, carb noise(air intake) and the fuse are the main culprits with the big gassers. I have cannisters and 3 blade prop on my 3W150 and again, a 40 size sport plane will be louder in the air than this set up. Imac measured at distances the noise generated while the plane was flying( the important part to complaints) with all sorts of props, engines etc while comparing it on the ground info. IMAC has come up with 24 ft away with the dB meter resting 24 inches off the ground and aimed directly at the prop arc with a standard of 98dB.
Turbines are very noisy on the ground, but get them in the air and again are barely audible.
Ducted fans are noisy on the ground, and noisy in the air.
My point is different standards on the ground should apply to different applications. A sound measurement is fopah if it doesn't correlate to the noise of the plane in the air. Again, in the air is when we get complaints.
none of this is perfect, and in urban areas noise is a problem. Certainly wish your club good luck
Ed