This would drive me nuts too, especially if I weren't able to sleep.

I wouldn't wait until September. Get witnesses to verify that the noise is unacceptable and start looking around for a quieter place now so that you have something much better lined up ahead of time.

Call the tenants association for your city and let them listen over the phone to the noise. Tape record it if you have to. See what they suggest.

I think you are stuck. Unfortunatly this is something that is out of the Landlords hands. Perhaps he will let you move early but I can't see any other leagal way out.

what about the cops? In NYC, this would qualify as noise pollution, and I might be able to speak to my precinct's community affairs officer to start a campaign of the cops going by the chasing them off.

But September isn't really all that far away, for that sort of effort. I'd be spending my energy to look for a new place.

call the cops if its after 10 pm, otherwise, what can the landlord do? its public space and sadly, only loud A**holes make use of it.