There is a beeping in my house. I think in the kitchen from attempting to track it down. It is not the smoke detector. It is not the oven, microwave, dishwasher, or fridge. It isn't regular intervals, sometimes it stops for a while, sometimes it's a few back to back, sometimes it's loud, sometimes it's quiet.
If you were designing a sound to be untraceable, this is how you'd do it. Which reminds me that years ago when I was at an old job, someone used their Arduino and a speaker to make something very similar. It was random in intensity and frequency and very hard to locate, the frequency was very low, so once you heard it you'd have to wait a while to try to locate it. It worked pretty well at driving people crazy.