OMG I have an iPhone 6 with the nuud case and this is happening! It's random and intermittent but it's approximately once everyone 5 minutes. Someone suggested it might be heat build-up but that is NOT true because mine does it even if it just booted up. It happens during phone calls and even while the phone is ringing when I'm calling someone. It's a deafening, painful screech sound - much more drastic than a simple "beep" as people are describing it.
Tried to return the case, which I bought 17 days ago, but the retailer Apex Wireless in Toronto will not take it back since they have a 15 day return policy. Lifeproof won't take it back since it wasn't purchased directly from them. This is such a scam and I can't believe I spent $100 on this **** case 😟