Audio files are saved in ogg format as preferred by Media Wiki. They should play fine with mozilla firefox, google chrome and opera browsers.
However, for Internet Explorer, you will have to install a codec for ogg files if you don't have one already.
Option 1 - To use VLC player
- download VLC player from videolan.org, about 20 MBytes
- make sure associated with .ogg files
Option 2 - To use windows media player
- close all instances of Windows Media Player
- download codec (directshow filters) from xiph.org or vorbis.com, its about 2.5 MBytes
- install the codec
- make sure windows media player is associated with .ogg files
Test the player
- Download an .ogg file (eg from here) and check you can hear it when you double click the file
Finally in Internet Explorer
- Open Internet Explorer and go to a wiki page with audio.
- When you click on the Play button, an error message should appear asking if you trust the Activex control - say yes
- If it is still not working, click on the "More" under the image, and select whichever player appears in the list
However, my experience with this in Internet Explorer is not great :( Best to try a better browser.
See Wikimedia Commons Help for more advice