2. You cant pick up that someone probably doesnt want to talk if theyre leaving an earbud in.
So what you're saying is, by listening to music, they're not paying attention to the conversation, because they don't want to talk, they want to listen to music, the fact that they can't focus on the conversation indicates that I should take a hint of "I'm not paying attention to this conversation". Or listening to music doesn't hinder the conversation, the conversation would be the same regardless of if they had a headphone in, in which case what about that shows they don't want to talk?
Not wanting to talk has no bearing on their ability to listen to your conversation.
