Toy Cricket Bat What Could This Noise Be? Subtle, High Pitched/like Ears Ringing Coming From Only One Room In The House.?

What could this noise be? Subtle, high pitched/like ears ringing coming from only one room in the house.? - toy cricket bat

Four family members of different ages, to hear the sound in a room. My son can not sleep in his room, where you can hear the noise. We have checked all the electrical appliances and toys, window (I thought it might be grilling and is not), TV, lava lamp, smoke, etc., can not hear the rustling in the closet or in the entry or any other room in the house. He even had his clock in the room. There is a constant, barely audible, high-pitched sounds as if his ears and sound is not sound real, but an eye / headache and if your room for more than a few minutes. What could that be? What else can we see? He sleeps in the guest room now, as it is unbearable. My husband and I listen to our 30, and my son is 10 and my daughter, is the 6th This is not a joke or a riddle ..... So please only serious suggestions. Thank you!