I've read on their forums about people having mic issues like yours and also random robot voice--where you sound like a robot to others. I've never had these problems. Got mine in July. I did have the little flashes initially but that was cured updates ago. Have you updated your rig? I'm currently running the public test channel v1. 43. It's basically a beta, a version or so ahead of the latest stable release.
I'm also running the Oculus Tray Tool. It has several tweaks including sound config. I have mine set to grab the RiftS mic and speakers when I'm using the headset. It releases those back to my PC's when I'm not.
Also make sure Win10 isn't using your mic for anything while using the RiftS, that may be a conflict.
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