I have the echo problem since installation of nougat on my S7 but this was only with speaker on.
Today with 1.8.1 installed, I have the echo problem even when speaker is off.
At least when the phone only had the echo issue on speaker, you could live with it, but now with echo with speaker off, its a bit of a problem …
So the 1.8.1 update has introduced a problem that was not there before.
There appears two ‘issues’ on Gitlab: