KE,
It truly isn't up to AMA (except as noted previously, to promote widest participation in some competition events). Examples are as close to me as two club sites I fly at. One is in a quiet (average ambient level is abt 40 dBA) semi-rural neighborhood, and the club standard of 90 dBA @ ft by coincidence with the former AMA recommendation is needed to keep received levels at nearest residences below the daytime ordinance limit of 55 dBA with some margin, after accounting for spreading losses. The other club site property (within 10 miles of the first one) is adjoined by a freeway, and ambient level at the nearest residences is typically 65-70 dBA. Although located within the same county and zoning is such that the same limit on sound level applies, the ordinance is in effect trumped by the the ambient sound level - a cop with a sound meter simply couldn't measure the contribution of the model engines if it is below ambient. An additional allowance of 10-15 dB at site #2 is very large, the difference between power to the prop delivered by decent .45 (7.5 cc) two-stroke and that of a 50 - 80 cc gasser.

Tinner,

Re: "If it offends anyone, especially a neighbor, it is too loud, and as I said earlier in my post... ," that's a really bad situation to be in because when it is true, your model flying freedom is at the mercy of the most sensitive crabapple within earshot. People's tolerance for noise generated by the activities of others varies widely. The folks that set noise abatement standards know that and accordingly recommend levels that are acceptable to most people most of the the time, fully realizing that not everyone will be satisfied and for a small fringe element, no perceptible sound level would be low enough. Objective ordinances offer some protection for those of us that make the effort to find out what levels they allow, and abide by them.