I had the same problem with fans even though they were in the next room they were keeping me awake, invested in an Airforce II, not cheap but very quiet and powerful this pulls air through a Rhino Pro filter and pushes through a double lamp cool tube using acoustic ducting hung using 10mm elastic bungee cord, for the second fan which is mounted on the floor I made a box out of MDF glued an inch thick polystyrene slab to the bottom and lined the box with 1/2ins acoustic plasterboard and acoustic foam on top of that, asked at the local builders suppliers if they had any damaged plasterboard got it for the price of a drink and got the acoustic foam off e bay for about £8 worked a treat, good luck with your problem.