This morning I heard a whistling sound, almost like a tea kettle, coming from the basement. It sounded like it was in the wall next to the steps leading down the basement, that is where the noise was loudest. I heard it in the front of the basement most, couldn't hear it in the back of the basement where the washer, dryer, and water heater and AC is. I've read it could be water pressure in the pipes (I noticed after I got out of the shower, but not sure if that is when it started or not), related to the AC (I have Central Air). Can anyone lend assistance?