Well i have the problem, that any jme application playing sound, has the problem of constantly stutterning if the framerate is low / or a garbage collect is, or similar. I guess if i could just increase buffer size it would go away, however I have not a clue where to archive this.
You should enable streaming for large audio files, also did you update to the latest versions? The audio renderer has been updated lately.
Hm no that did not help.
In fact my audionode was not streaming, however when I set it to streaming I hear nothing at all anymore.
(Maybe also relevant the welcome screen of jmp has audio stutters as well, and same goes for one other lwjgl game I know.)
Noone any idea? 
I don’t think the issue is buffer size, if your sound is not streaming then OpenAL has the entire uncompressed sound file in its buffers so any issues that happen are in OpenAL.