Just in case you weren't already aware of it, there are some pretty nifty tools available in Moodle (via Wimba) that allow you to draw on real voices rather than just text-based activities. Two of these are Voice Boards and Voice Emails.
The first tutorial below demonstrates how to set up and use Voice Boards in your Moodle courses:
And for something with more in the way of privacy and 1-1 options, you might like to also check out the Voice Email tool:
For more Moodle tutorials from English Raven, check out the entire list here!