Earlier quoted context omitted.
I have been able to trigger it when fumbling around with adjusting the fit. If I run my finger over the top of the body I can get a brief squeal out of them. Happened just a few seconds ago. I also have noticed on multiple occasions that if I take them both out of my ears and cup them in the same hand, they squeal audibly enough to hear faintly from a couple feet away. The skin contact sensor is very sensitive. Howev…
Just curious, which Sennheisers did you give up on in favor of APP3? I have over-the-ear Momentum 3 and love it, but if APP3 provides better sound quality and better ANC I might consider switching as Momentum 3, while I love it, is bulky, heavy, and started to wear off and break down.
FWIW I got mine at Costco and their return policy is top notch, and I believe they include AppleCare+ with the purchase. I had bought my APP2 fairly recently before the APP3 were released, experienced buyers remorse, but had kept them in like new condition with the box and accessories, and had no problem exchanging them.