there is a high pitched whistle in my home and its driving me crazy !!!!!!

My husband looked for maybe 10 minutes and said he thought it was a toy and has done nothing since. We narrowed it down to one section of house.
Ive checked all the toys. he checked the a/c and it cant be heard in any of the bedrooms or attic. I hear it closer to the ceiling...I think.:



WHAT IS IT????????????? AAAAAAAAAAAAGH!!!!!!!!!