Kaizena is a free Google Docs Add-on that makes it easy to add voice comments to your documents and to the documents that students share with you. Today, the Kaizena team announced a new streamlined version of their Google Docs Add-on. The new version lets you record your voice comments without having to ever leave the document.
http://www.freetech4teachers.com/2018/01/kaizena-streamlined-voice-commenting-in.html