You know how when you have audio playing in a tab you can see that little speaker icon? Well, there’s a setting you can enable so that that speaker icons doubles as a mute button so you can mute the audio.
Go to
chrome://flags/#enable-tab-audio-muting
and click enable on the flag it lists there (”Enable tab audio muting UI control”). Then, restart Chrome. With it enabled, you’ll be able to do this: