A:Answer You can do what you're asking with the right bud, but since the right bud is the one that connects with your phone, you need to be using that one.
So no, you can't use just the left earbud, but you can use just the right earbud.
I keep the right bud in my ear all day at work, only taking it out to charge, and I'll leave the left one in the charge case.