I once heard a sharp ringing in my room when my lights were off, it turns out I can hear streetlights from, like, really far away.
It was around three in the morning. The kind of thin, high ringing you get when a wire is pulled too tight — except there was no wire, and my lights were off, and the room was dark enough that I could see the shape of the ringing against the inside of my eyes.
At first I thought it was me. Tinnitus, the doctor had mentioned it once. But the ringing moved when I turned my head. It had a direction. I sat up and turned slowly, and the sound swung with me like a needle finding a station, until it pointed, unmistakably, at the window.
Outside. At the end of the block. The streetlamp — the old orange one that flickers when the wind hits the pole — was singing. Not loudly. You'd never notice it walking past, head full of your own thoughts. But lying there in the dark, with nothing else to hear, I could make out the exact pitch of a lamp two hundred feet away.
After that I started noticing the rest of them. They're all different. The sodium lamps down on the main road buzz low and steady, a held note. The new LEDs whine, some of them, a brighter, thinner complaint. The transformer on the corner has a wobble in it, like it's slightly out of tune with itself. The whole grid is humming, if you're quiet enough to catch it — a choir of electrical voices most people have been taught not to hear.
I don't hear it the way I used to. It's constant now, a background hiss under everything, and I've mostly stopped noticing. The strange part isn't when I hear it. It's when it stops. Every so often, all of it cuts out at once, for a half-second, and the silence where the lights should be is so loud it hurts. I've started to wonder if they're not making the sound at all. If they're listening to each other, and the quiet is them all holding still to hear something else.