OP here! Made an account to follow up. First time one of mine has ever made it. Thanks for the ideas, actually. If it had been an annoy-a-tron someone was going to die. Here’s what it actually was: Too Long, Won’t Read: Several people called it. I found a defective monoxide detector dying in a dark basement corner, but only after I went insane and and fought a tiny spider with a wooden sword. Further Reasonable Explanation: Six months ago I took down a defective monoxide detector and replaced it. When the defective one vanished from the kitchen table, I assumed it was thrown out. In reality, it had been returned to the basement and tossed into the dark reaches of the crap zone, awaiting the day the batteries would die (who put batteries back in it?!), freeing it to wreak havoc on my brain as it struck madness into man and drench my house in dog shit as it struck terror into beast, then luring me into its crappy, spider-filled lair to do battle and put it out of its lifelong pain once and for all. The way the sound seemed to move around the house, making it impossible to track? I had assumed it was the same volume the whole time, but it had become sporadic as the machine’s strength gave out. When it seemed loud in one spot at one moment and quiet when I came back, it really was just quieter, not farther away like I thought. I have now put the functional alarms back, since it was clearly not them making me crazy. Epic Tale Version: I had tracked it into the basement. It had to be there. Nowhere was it louder than here in the concrete box that is my basemen, but it was still on the move. I chased it back and forth louder here, then softer, then louder in the exact same place, from disabled smoke detector to disabled CO detector, ripped from the walls, gutted of their batteries, making no sound. And then it sounded right next to my head. After hours of jumping a the sound, this time I froze instead. I turned slowly, thinking, this is it, this is the child-sized carnivorous cricket sitting on a face level shelf, it has lead me here to devour my skin. I turned slowly. Nothing. No uber cricket, but also nothing else that could make that noise. 

It had to be on the other side. Good god. The shelf I was looking at sectioned off the storage part of the basement from the part humans might actually want to enter. It blocks a nasty cement wall from view and hides the various boxes of crap we want out of the way for most of the year: Christmas decorations, forgotten crap that has not seen daylight in a decade, and spiders. Good god, the spiders. There was the chirp again. Yes, it was definitely in the crap zone. I peered in. I did not see any exotic looking torture devices planted by the NSA to turn me into a supervillain. I did, however, see at least one spider. Not 100% past a long-time fear of them, I didn’t want to kill it with my bare hands, so I looked around for a suitable weapon. The nearest blunt implement? A wooden sword, left carelessly on top of the freezer, even though it has been firmly established that that is not where toys go. I grabbed it and waded forward, firmly vowing that by god, even if a spider crawled on my face I would not shit myself. Killed the spider. Nudged a few webs out of the way, also with the sword. A second spider scuttled over a box, narrowly avoiding the wrath of my blade. The chirp sounded right in front of me. My sphincter winked roguishly at the inside of my underwear, but did not fail, because damn it I am an adult. An adult, going slightly insane from an auditory version of Chinese water torture, hunting an inscrutable beeping sound, brandishing a wooden sword at spiders while knee deep in crap I should have organized years ago. I look around. Its here. I need one last chirp to find the exact location- There. There it is, in the corner. A small white device. I let out one final burst of my mighty battle cry: 

“GOD

 ******* 

DAMN IT” and seized the monstrosity, its final chirp dying on its speaker as I pried out the batteries. Victory was mine this day. Man conquered machine and madness, spider and sudden realization that my god I need to clean that basement this summer. And then man cleaned up an enormous amount of dog shit, again, because even though it would have been best to leave dog outside and not subject him to a repetitive high pitched sound that made him lose control of his anus, it was just too hot out for to leave him out there the whole time.