I would say riding a local commuter train (ie. on the JR Yamanote-line in Tokyo) versus long-distance (ie. the bullet train/shinkansen) might be a sufficient different environment that talking is more accepted.
As long as one isn't overly loud, of course.
If you're outside of one of the "quiet zones" (like the local commuter trains or the subway); I find that people are really warm and friendly and doesn't mind talking for a while or helping you out a bit. I guess it helped a lot that I spoke some bare minimal Japanese (to the point where some started talking English to me, as the conversations approached more medium/advanced territory).
As long as one isn't overly loud, of course.
If you're outside of one of the "quiet zones" (like the local commuter trains or the subway); I find that people are really warm and friendly and doesn't mind talking for a while or helping you out a bit. I guess it helped a lot that I spoke some bare minimal Japanese (to the point where some started talking English to me, as the conversations approached more medium/advanced territory).