Adding a voice comment is a great way to provide personalised comments.
With Google docs, it is possible to provide audio comments free.
As shown by Jennifer Roberts in the above video, it is as simple as using an app to add audio comments. They can be edited, re-recorded and deleted.
Add audio to a documents
Edit and delete an audio comments
The comments are saved and attached to the documents
The audio comments can be shared
You need to have a Google account
The documents are linked through Google docs