This is high on mine as well. The idea would be to have sounds files as part of the resource library. The GM would then be able to launch these in a player or have the launched on a client via macro trigger.
I have sort of a framework in beta but it's been a while. Real life is really getting in the way this summer from making good on getting any meaningful work done on all the half done code and merging my personal build with 1.4.x. Ugg.
I was also using JavaFX and a couple of other libraries, so was sort of waiting on how that pans out with Java 1.8, as I was initially having issue getting the proper runtimes packaged for the build.
However, what I did/do have is a new window/panel/tree/explorer (like Map Explorer panel) that holds "Playlists". Double clicking (right click-add) on an MP3/Wav file in the asset window (which I also added .mp3/wav as showing up in the asset windows) would add said audio file to the playlist. From the playlist window you had standard play/pause/ff/rw controls and it would play to all connected clients (using standard MT asset transmission protocols). The asset window also displayed the Album art for the mp3 or a standard icon if missing.
Along with that there was also a couple of macro's to start/stop/play audio files (to local or remote clients). It all basically worked but I still have lots of bugs to squash (playing multiple files at once had issues, reliably stopping said audio, adding ability for client to "mute" pushed audio, etc). Also a bug where audio files showed up in other asset windows where they shouldn't, like textures when painting... Also still had to work on saving set playlist data to the campaign file...
I only post, in case someone else wanted to take the mantle, I'd share what I have so they wouldn't have to start at nothing, or use it for ideas. It touches a LOT of classes where it comes to assets but most of the audio playing/playlists, etc are in their own classes.
In anycase, it was a neat POC that getting audio in MT wasn't impossibly hard. But to be honest, I always "think" adding audio to my games is cool but the novelty usually wears off, and the number of times where it really is needed, playing the audio outside of MT has been easier.