Perhaps @T Boog build a bass trap for the out side, with additional vinyl sound proofing mat.
Replace you window with triple glazed, the inner pane set at an angle, then the void evacuated of any gas.
With another internal bass trap.
Though I think that approach may be prohibitively expensive. Perhaps start with the Advanced Acoustics premium mass loaded vinyl mat. The page I read recommends sandwiching between two sheets of high density acoustic plasterboard. Plasterboard is surprisingly effective, I have two layers of that on the doors, walls and ceiling of my studio.