This thread especially piqued my interest. In one of the group therapy groups I run, I've been experimenting (more in the artistic sense than the scientific sense) with incorporating sound and music into our regular session-opening meditations. This particular group is not super high-functioning and represents very low education and socioeconomic strata.
Mostly, I've been pulling from ambient artists (I try to keep it to ~10 minutes, so it's challenging to find pieces that length), but I've also experimented more conventional artists (call it "intentional" vs ambient music?). Oliveros' Deep Listening is, of course, designed for this, more or less, and I personally find much of Reich to be very meditative, but some of my less stable patients found it quite agitating.
I find myself reaching into my (comparatively limited) musical repertoire and choosing based on my gut. I haven't found a lot of guidance from research on what works, either specifically or in principle. As a clinician, my access to literature is limited compared to when I was doing research. Anyone have leads on solid studies of the utility and application of music and/or sound to meditation?