I noticed a separate issue today when calling someone from my phone in a noisy restaurant environment. This is a restaurant I have called from before with my S8+, and the conversation was totally normal. With the Note 8 though, the other person couldn't hear me at all, other than a couple times there was a brief bit they could hear something. I could hear them just fine. Had to hang up and call them back from the truck.
So this is two different Note 8's with microphone issues. Ideas? Have you noticed any issues with your Note 8?