Why not record your spoken notes?
Not all clients that I work with have computer and network facilities capable of processing audio files. So I store them on one of the web sites that makes it possible to record and play back my voice right on the site, soundcloud. (I am not claiming that it's the best or anything like that!) I mark my recording 'private' and then send it as a URL to the client in an email in which I explain what it is. The benefit to the client is that she can listen to the recording as many times as might be necessary. The benefit to me is that I find that I can critique a résumé that is 'not too bad' in about three minutes.
There is one additional wrinkle in the solution that you might face too. If your microphone is like mine then you will have found that it is good enough for Skype but too feeble for soundcloud. To remedy this problem I do my recordings with Audacity—which also provides a benefit. After I have used Effect | Amplify to increase the volume of my recordings I can then use Effect | Noise removal ... to eliminate some of the background noise. The recording that I save and then upload to soundcloud for the client is much better and all this takes very little time.