I noticed it when I was pregnant and my ds is 18 months old now so it's been going on for bloody ages.
It's like intermittent road noise but we can't hear the road from our house. I normally only hear it at home but heard it somewhere else last night so now think it's my ears?
We've hunted high and low for any noise source at home down to turning the electric off to see if it was that with no result. It's starting to drive me mental. Any ideas what it is and how I can get rid of it?