Practising in silence and then testing on public transport. If you can't meditate anywhere, anyhow, despite the external circumstances then many of the benefits won't be available when you need them. So any music, any style would probably do.
Well, for "lower case" I'd recommend the guy who made up that little title, Steve Roden. His work is always suitably soothing and quiet. Also, Bernhard Gunter and M. Behrens.
