Maybe this will help someone.
PoodLL filter, PoodLL Repository and the PoodLL Once Player. This is what I use to play an audio once (student listens to it once and then answers a quiz question). It's now on my blog too. Actually the main reason why I post it here is as a record of how I did this kind of things. I'm afraid that my memory will fade over time, and Moodle.org's forums are a form of archive for me to dig up when my gray matter fails me.