Cannot block player and Voice chat mode turns on microphone mode but does not speak！
Hello!
Sorry for the late reply.
If you mean on the Battle.net app itself, you can click the person, and drag their volume bar to increase or decrease their volume. Sliding to the left with stop their open mic bothering you, but if they’re your friend it may be better ti ask them to use push to talk, or to install a noise gate.
If this is for overwatch, please see:
If it’s for Call of Duty, please see :
For other games, please re-post on forums for the game you’re referring to 