If you absolutely need to run the generator, see if you can place a noise baffle between the generator and the neighbours . Bushes work well, as does plywood, wall board, etc. Ideally three sides and don't forget the top. Aim the open side where there is open space. The baffling is equivalent to a lot of distance.
It is not just the intensity that affects people. The length of time they can hear it makes them more attuned to the sound. I had to deal with 60 cycle hum at work, and even 40 dba would draw complaints, because it was continuous.