There examples of accessing audio devices here;
http://www.news2news.com/vfp/?example=279&function=435
Take a look at the list of commands on the left side.

>Hey folks, I'm wanting to develope a VFP9 App that utilizes the API/MIDI calls. How can I make MultiMedia Calls in VFP9? Is there a book I can get or can someone give me the basics on how to make calls like mciSendCommand, thanks