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I think the club should adopt the 96 dba at 3 meters on grass that the IMAA has adopted.  Also, AMA has used the 96 dba limit for pattern events.  The advantage (besides keeping our neighbors happy) would be to have our models set up to meet this limit, making it easier to participate in the AMA and IMAA events around the country.
Based on noise readings taken of some models at our field, this limit is easy to meet (and already met in most cases).
Noise comes from the propeller, the engine exhaust, electronic equipment and the primary and sympathetic vibrations caused by out-of-balance moving parts. Much of the excessive noise is caused by propeller tip speed approaching the speed of sound. Tip speed can be lowered by reducing the propeller diameter and using 3 or 4 blade props.  A 12-8 two blade prop can be replaced with a 11-8 three blade prop and will keep the engine loading the same (while providing additional ground clearance!).
My Hobbistar 60 with the Veco 61 and open chamber tuned pipe weighed in at 108 dba.  My other Hobbistar 60 with a Saito 80 measured 84 dba, yet the performance in flight was nearly the same. The difference is prop noise! The Veco ran at nearly 14,500 rpm, while the four stroke was barely 8400. Changing to a 12-8 three blade Graupner prop reduced the sound pressure to 84 dba!
Some experts recommend that the prop tip speed be kept to 45% of the speed of sound to stay at or below 90 dba. Prop speeds reaching 55% of the speed of sound will cause readings of around 95 dba. 70% will be at around 105 dba.  Lets look at some examples...
The speed of sound is around 771 MPH at 70 DegF. Prop tip speed can be calculated as (Pi*Diameter*rpm)/(12*60) = tip MPH.