I am a huge fan of using different media formats in order to give the best possible feedback to students. Feedback is not all created the same and I do think that we waste a lot of time by creating ineffective feedback that never helps the student learn and improve. If our feedback does not lead to improved learning, we should probably not be wasting our limited time on that.
There are many ways to give digital feedback in Google Apps and some tools have offered some options in the past, but my new favorite tool for giving audio feedback is Mote. Mote is a simple to use Chrome Extension that allows you to easily record audio segments to put into a Google Doc, Google Slide, or even a Google Form. There are some free options when using the tool but this is one of the few tools that I think schools should pay for. I am not always impressed with all digital tools that have costs but Mote is a relatively cheaper tool that can have a large amount of impact. (I also think teachers should never have to pay for tools and that schools should be paying for them, but we have to ensure this will be a good use of the money and not just a shiny tool that appears to be good but does not actually lead to improved teaching or learning.)
Watch the following video to see how Mote can be used to give effective feedback. If you are still not sure what should be included in effective feedback for students, check out this article by Grant Wiggins on the Seven Keys to Effective Feedback that has always been a favorite of mine to share.