Twitch in the URL automatically mute?

I would like to have my friend as a cam in Streamlabs OBS. Problem is that the sound is heard from my livestream. The program in the audio mixer I would not like synonymous because of the alerts. Can one somehow do that in the URL already that is muted? Eg: http://www.twitch.tv/...twitch.tv/ EXAMPLE / mute or so in the art

This is definitely not the case with the URL. Maybe that's what's stored in the cookies