I think you can do this with any website, that is how browsers work (i.e. if the browser can access the file, then most probably the user can too).
Your best bet is to stream the data from an online source (instead of bundling the audio with the project). The Video plugin allows you to open a URL, maybe you can use it to stream audio from a URL (i.e. video with audio and black background).
I have seen some sites protect their files by streaming them using JavaScript. But I don't know the exact way.