Sometimes you might be able to get your message across more clearly if you include video rather than audio. You can buy an inexpensive camcorder to record yourself, use your webcam, or create a screencapture video with software. Nowadays, you can even create a great video using your smartphone.
This type of personalized message also shows people who they are dealing with, which can definitely increase conversions!
In fact, you can kind of “kill two birds with one stone” by uploading the video to YouTube as well. That way you will get views on YouTube, and it will help increase conversions on your own website, too.