1. Necroposting is bad.
2. You wrote that you've installed the plugin, but you didn't mentioned anything about its configuration. Also you've asked the question in a wrong way: to begin with, you didn't specify what exactly you've done, what you've expected to see, and what you've actually got. Though, it wouldn't change the whole picture, since the plugin is unofficial, so you won't get official support for it anyway.
3. No, in this particular case one could not simply modify the source code to make sound repeating. Since you're talking about the javascript part of the project, it should be recompiled after any modifications.
And leaving aside the fact that any modifications of the core leading to problems with future updates, the only "loop" there is the property of dynamical html5 element
audio, which should be set to 'false', unless you want to hear never ending sound (no, in that case it will not stop at all regardless of any actions until one close or reload the page).
I can sling a little html, but that's it. I'm hoping for an easy solution for changing that sound to a loop.
There is a plugin. Install and configure it. If you have any troubles, ask developers of the plugin (not here, I bet they're not monitoring this forum). That's an easy solutions. All other solutions will be much more complicated.