hello….I live in a groundfloor apt. there are two a/c units right outside my bedroom window, about 2 feet away...my unit and my upstairs neighbors' unit. i don't use mine much, but they use theirs ALL THE TIME, even when it's 65 outside! i really don't want to move, but i cannot go through another summer of listening to the pervasive deep buzzing sound of their unit. so far, i have tried styrofoam insulation and also sound board, cut to fit into the window on the inside which has a 3 inch sill all around it. have also hung a heavy thick blanket.