I just took my iPhone in for repair because of some weird screen flickering. They did a diagnostics test and couldn't find anything wrong. They were about to send me away and do nothing for me when I pointed out the distorted glass sound.
Basically, if I'm on a call, whether on speaker or regular style, and I get a text message, the sound is distorted (set to glass). But if I'm not on a call, it's fine. And if I'm using headphones, it's fine.
Anyway, when I pointed out the issue, the genius said, "That's not right, let me swap it for a new one."
He did. Activated it. I left the store. Same issue.