The Philadelphia regional accent remains arguably the most
distinctive, and least imitable, accent in North America. Let’s
not argue about this. Ask anyone to do a Lawn Guyland accent or
a charming Southern drawl and that person will approximate it.
Same goes for a Texas twang or New Orleans yat, a Valley Girl
totally omigod. Philly-South Jersey patois is a bit harder: No
vowel escapes diphthongery, no hard consonant is safe from a
mid-palate dent. Extra syllables pile up so as to avoid
inconvenient tongue contact or mouth closure. If you forget to
listen closely, the Philadelphia, or Filelfia, accent may sound
like mumbled Mandarin without the tonal shifts.