Susan Berkley is making money out of training people to speak in the way that she considers to be correct. I have no problem with this, and if you want to make money doing voice-overs in America, follow her advice. However, what she considers to be a mistake is not necessarily what most of us do,In some AmE and CanE dialects, /t/ is voiced in certain positions, sounding very much like /d/. This is not 'uneducated'Do you say “qualiDY” instead of “qualiTy”?
Student or Learner