<p>We have a JavaScript construct that will play .wav files within Firefox on Windows and MacOSX, but it does not work for Red Hat Linux.  What extension do I need?</p>

Firefox 3.1 will support
Firefox 3.5,  supports the
```
<audio>
```
tag, a standard tag to deal with sound. If you use that, you'll need no extensions.
Unfortunately, that will only work with the latest browsers (Firefox 3, for example, is the latest stable version and yet does not support this tag. You may have trouble making it work with Internet Explorer too).