I'm guessing drones. This was from an article in September, before the recent conflict, talking about the constant noise of drones flying overhead is an ever present source of fear and anxiety in Gaza.
Some excerpts:
"Unmanned surveillance aircraft have become an integral part of Israel's 15-year-old blockade of the impoverished enclave, and 2.3 million Palestinians endure their incessant hum."
"Gaza teenager Bissam says she has trouble sleeping and concentrating as the buzzing sound of Israeli military drones above the crowded Palestinian enclave drives her to distraction."
"Sometimes I have to put the pillow on my head so I don't hear its buzz," she said, adding that the drone noise gives her headaches."
"He told AFP that "the buzzing of the drones and the intermittent raids of the F16 (warplanes) have become an integral part of our lives"
Drones were actually my first thought, but I couldn't believe that it would be constant like that. I flicked through a few different livestreams before finding the good/reliable one I linked and it was in all of them, all the time.
Really crazy. Thank you for linking the article!
Edited to add - wow that article made me strangely sad. It's not so bad compared to everything else that is happening there, but somehow it just added an extra layer of sadness.
Right? It's something you usually wouldn't think of compared to the bombs and stuff, but it really would be terrible, living under that constant noise. It's like some accidental mental torture.