Abort loadSound()

I’m building a little applet with audio-files. Each level starts with loading an audiofile.
I also use the history api of the browser, to give each level a usable URL.

Now if a user changes the history state, while loadSound is loading the sound, a second request is executed, and the feedback provided to the while_loading callback of both those requests is competing, creating some very funky loading bar behaviour. Also the

Is there a way to abort loadSound() to stop this from happening?

I looked through the code, but I found no way of getting to the XMLHTTPRequest to use .abort().