I had one professor in grad school that provided audio feedback on our assignments, which I appreciated, and looked forward to very much even if it was not all positive. Not only did five minutes of feedback pack a lot of punch, but it felt personal, and I found myself putting extra effort into all assignments in his class.
Audio feedback personalizes any online class. A few minutes of precise feedback is enormously important and valuable to any student. Jump the minor technical hurdles and become a more effective online teacher! Use Audio to deliver feedback!