I think a big difference is the assumption of the kind of meeting you are in; for most of the business meetings I consider valuable, if there is someone distracted by a transient issue the meeting should stop and wait, and if it doesn't they are just going to have to stop everything themselves to request things be repeated for them. If you are in a meeting and it doesn't matter if you are distracted you aren't really participating, are you? ;P So like, definitely mute the call as you are just an observer.