Vista introduces a new concept to managing your audio settings. Instead of having a collection of fixed settings, such as Line In, Mix, etc., it dynamically updates the volume controls letting you control each application individually. This is a huge benefit, but may be the source of your problem.
To check this, open Control Panel->Hardware and Sound, and leave that window open. Next, launch Internet Explorer, Windows Media Player, or whatever application you are using to access the content, and begin playback. While it's supposedly outputting the sound, click "Adjust system volume" from under Sound in that control panel window...you should see a volume control for that application. Try adjusting the bar for that and other running applications, as well as clicking the speaker icons underneath to toggle the sound on and off.
If that doesn't resolve it I would consider missing audio codecs, but check out that one first.
The thread at this link
did not solve my problem. I'm puzzled. I run Vista Business. No streaming audio works whether it be from Real Player or WMP. I can get video feeds just fine but no audeo. Also stand alone audio feeds do not work. Any help is greatly appreciated!
Flash audio works fine.
I've googled this over and over and went to ~page 12 with no luck in solving anything.