Regional accents are a dying breed, at least in the US where so many people move around so much in their lives. There certainly is a NJ accent, and a Boston, Chicago, Michigan, Alabama, etc. I never developed much of an accent, but those who know me say I sound like the New Englander that I am. But when I'm singing I tend to "purify" the vowels as i was taught classically. My vocal tone isn't classical at all any more, but there's no regionalism in my singing voice.