Quora: What is the origin of the distinctive NPR speech pattern?
Nice answer by Andy Carvin of NPR:
We also offer training to on-air staff so they can work on their delivery. There’s even a book called Sound Reporting, by longtime NPR producer Jonathan Kern, that talks about on-air delivery, including how reporters and hosts make notations on paper copies of their scripts to specify when they want to emphasize a word or syllable, pause for a beat, etc.
Don’t miss the comments too, where Carvin talks about how they work on pronouncing foreign names correctly and consistently.