I could hear a fait beeping in one corner of my kitchen, but if I moved ~3 feet in any direction it disappeared. Eventually discovered that it was some kind of

I could hear a fait beeping in one corner of my kitchen, but if I moved ~3 feet in any direction it disappeared. Eventually discovered that it was some kind of acoustical beat frequency from the motor noise in the refrigerator reflecting off the back wall. Moved the refrigerator ~1 inch further away from the wall and the sound disappeared (at least from the location I had been able to hear it)