I could not help but recall J.K. Trotter's charmingly deranged old Gawker blog, "How to Find a Beeping Smoke Detector If You Don't Know Where It Is." His revelatory technique: Once you have not found the smoke detector where you expected to find it, continue looking in other places until you find it. I thought of this as my wife and I hunted a mysterious high-pitched ringing sound around the main floor of our house. Trotter had eventually found the smoke detector beneath the bathroom sink (!), in the back of a cabinet (!!), covered by a bag of sand (???), nowhere near the sound's seeming point of origin, a phenomenon he discovered was due to the auditory qualities of the alarm's sound and the acoustic properties of his bathroom. (It's a good blog!)
It was a sustained, maddening, high-pitched ringing sound, not all that unlike that made by a smoke or carbon monoxide detector when it's actually set off. We couldn't figure out what was making it; though it sounded vaguely alarm-like, it also clearly was not the sound any of our various alarms make. It seemed to be originating from the bathroom, but like Trotter's sound, not from any discernible point in the bathroom.
Once we had exhausted all of the sane or explicable places to look for its origin, I did indeed have the thought, OK, well, then it is time to look in places that do not make any sense at all. The simple and inarguable fact of the matter was, it was coming from somewhere. If it was not coming from a sensible place, then that simply meant it was coming from somewhere absurd.
The problem was, the next most sensible-seeming action, after we'd opened all the cupboards and looked under anything with space beneath it, was to look inside the wall. The sound sorta seemed like it was focused on the back wall of the bathroom, or anyway near it, and we'd already established that wherever we found it, it wasn't gonna make any sense. The most hateful outcome would place the sound's origin behind the wall, and then we'd have to hack a big grisly hole in the wall and fix whatever was making the sound and then patch up and paint the wall, and we'd have to do it within our home maintenance budget, which presently is absolute zero. So naturally that felt like where this story was headed.
As a sort of desperate last resort—less to find the source of the sound than to console myself that I'd exhausted every conceivable ludicrous possibility before inevitably and expensively hacking into the wall of my home—I moved a few things off the top of the toilet tank, and lifted the lid. The ringing instantly grew much louder. I bent down to bring my ears closer. The ringing sure as hell seemed to be coming up at me from the depths of the toilet tank.
I am not a plumber, but I have been a homeowner and toilet user for many years. I've fixed toilets and replaced their inner workings; I've had plenty of occasions to look down into the mechanisms of this particular toilet. If something were much different down in there—if, say, it suddenly contained an angry carbon-monoxide detector for some reason—I'd notice it. Everything looked normal. So far as I could tell, the only way the toilet differed from the last time I'd looked down in there was that now it was screaming at me.
Listen. Sometimes the universe is kind to you. In these moments neither the wise nor the broke will dare question this dispensation. If the ringing could be coming from inside the toilet tank, rather than inside the wall, then maybe also the ringing could be stopped in the very dumbest and cheapest of ways. I flushed the toilet. The ringing stopped.
Cursory internet research tells me that a toilet can ring when parts of the fill valve become old and worn, causing them to vibrate. I now understand this in a far-off, casual sort of way, with the sort of "Huh. That's interesting" with which you might respond when your kid tells you an interesting fact they learned about a moon of Jupiter. Huh. Europa has liquid water. Huh. My toilet rings like a phone sometimes. Not my problem. It only rings sometimes.