Dialect, Speech
If you listened in to the private lives of twenty people, all of them would have different dialects and ways of speech. Whether they actually use these dialects with you is another story. But when they're alone, or with other people who are from the same place, their speech will be different.
Can you even imagine twenty different dialects in your head? Well I can tell you that there are definitely at least twenty of them in Japan alone.
べん
None
None
The best way to learn someone's dialect is to buy them a bento (べん) from where they're from. Not only do these bento have writing in their dialect on them, but their speech will immediately shift to match. Then you'll be able to hear how they sound in their head and in private!
It also helps that bento are delicious, and anyone with any dialect will love them.