Thing is, the 4 stroke exhaust pulse wave is lower than a 2 stroke, the lower pulse wave travels much further and dissipates less than a high frequency 2 stroke.
Track set up and having a way to dissipate the pulse is key to keep the pulse wave away from neighbors.
A place like Smith Road where they are basically in a valley but having their starting line (exhausts facing the street) is a bad place to have it. The rest of the track is good that it is in kind of a valley (high mound train tracks on one side and high area by pond on the other) save them in keeping noise relatively dampened. Routing the direction of straights NOT exhaust facing neighbors should be a must. Summer tree coverage saves them.
Meadowlarks should be relatively quiet because most of the track is parallel to the highway/rail line, except down the hill where you enter (which I suggest they remove) because the noise of the bikes powering up the hill is a BAD idea, that and I would assume dust would be their number one complaint. Remove said area and make a raised berm across the top of the hill to contain the noise.
Walk around your track layout and think like an exhaust outlet, look where it would point under acceleration, if it points to mankind, re route or change direction.
Easy things that would help out with little or no cost on track owners.