Keep noisy machines away from your bedroom and living areas. Situate your home so that your bed isn't right next to your noisy furnace or air conditioning unit. If there are any other sources of constant noise, try to locate them far away from your sleeping and living areas so you can have some peace and quiet.
You might also want to consider using these machines less to give yourself a break from the noise. Turn off your air conditioner and open the windows, even if it means being a little hotter than normal. You might find the less noisy atmosphere more relaxing than a cooled-down room.