Please set your mic to Push-To-Talk

[Da]

By default mic is set to Open, so in every game there are 1-2 ppl with background noize, breathing, coughing and sneezing, but not talking.

To change that you must go to Options - Audio - Voice chat. There are plenty of options, but the most classic is Push-To-Talk, when you hold a button and speak.
By default it is Caps Lock.
You can change the button in Options - Mouse and Keyboard - Change Bindings - Communication - Voice Activation.

[Osama Bin Trippin]

That's a perfect environment to start playing Nasheed in.

[Danger Dan]

No, you cannot change the Push to Talk button, There is no key bind option for it and a far as I can tell there isn't even a way to specify which devices you want to even use for chat or audio and are stuck with whatever your PC has active on game launch.

[McFuzz]

*eat chip, have family argument, dog bark, heavy breathe*

[McFuzz]

My favorite was "Oh wait I think this guy can hear me. Aight lemme set it to push to talk. Aight that's better now he can't hear me."

Yes. Yes I still can sir.

[Locklave]

Never!

[Corey Greyfox]

You can set other players mics to mute by default. I only unmute friends.