My WH-1000XM4 are about 16 months old. Today the right earcup nearly burst my eardrum - it suddenly made a loud, whistling noise that only appeared when I put the headphones over my head. It lasted for maybe a minute or two, during which I disabled BT module in my phone and PC so they would fully disconnect, that didn't help. The noise was there with the ANC enabled and disabled.

After resetting back to the factory defaults (both buttons held until the LED flashed four times) and pairing again they worked fine for a few hours, but it just happened again, this time in the left earcup. The noise modulated as I moved the earcup to and away from my head, lasted for about 20 seconds and stopped.

It was so sudden and loud I'm now scared of using them and damaging my hearing.

This is my second pair of WH-1000XM4. I had to exchange the first set only a couple of weeks after purchase due to loud static hiss from the right earcup. "Disappointing" is a gentle way to describe my experience with a £349 premium product. I use them only in the house and at work, never been out in a rain or dusty places. 

I got them in Argos UK (store, not online) in September 2020. I registered them on Sony website, I'm trying to find out whether they're covered with any extended warranty from Sony.

Has anyone experienced this problem? And Since this is an intermittent issue, what are the odds of them coming back with "couldn't replicate the fault" note even if Sony still covers them?