The one lucky stroke I have is that our appartment complex has a huge wall built of some kind of thick plastic or something that is designed to block out the road noises (which it accomplishes quite well) I don't think it does anything for the sky mag, but it blocks out many of the immediate area street lights.
I'm almost certain I can't see mag 4 stars when the moon is out here. I'm now second guessing myself, but when there was no moon I believe I made out a mag 4 constellation, well anyway I haven't been able to see it at all since the moon is over the horizon now, not even a single star from it.
I am very interested and curious to hear from you as to whether you can see magnitude 3.8,3.9,4.0, 4.1, 4.2 or 4.3 stars from your location at all, at about 45 degrees or more altitude on a clear nearly moonless night with good transparency?
I use Skymap Pro 9 or 11 free demo, it's a simple but VERY handy and usable and intuitive planetarium program, to see what brightness certain stars are (make sure not to use variable stars if you can!) so I can do the test.
I pick fainter stars in Ursa Minor, Lyra, Draco, Pegasus, etc. since then I am familiar with the constellation shape and can see where a faint star is supposed to be. Use AVERTED VISION to detect the faintest ones, aim your eyes to the right of the faint star by about 1,2 or 3 degrees and then you will see much fainter things than by direct vision. Make sure you have been "dark" adapted by at least 15 to 20 minutes with NO direct lights shining into your eyes from anywhere.
Then finally when you have seen which is the faintest one you can see, do the same test but now pick stars overhead or close to it. That last part is one I need to do soon.
I'd be interested to hear what your results are. So far I got mag. 4.36 with a 75 per cent phase, shielded moon which was 45 degrees up, for stars 40 deg. up from my Northern horizon. I can't hardly begin to imagine what it's like from parts of Nevada or Galloway Forrest Park, Scotland (our darkest place here, even Llampeter Wales is brighter! and that's DARK) or Hawaii where you can see down to mag. 7 with the naked eye