Through the first four books, Jim Dale has been pronouncing Voldemort as 'Volde-more', and Hermione as 'Her-my-knee', but with this book, he's now enunciating the 't' at the end of Voldemort, and is now pronouncing Hermione as 'Her-my-uh-knee'.
It's taking a little time to get adjusted to the change after having been used to hearing them pronounced one way for so long. Especially Voldemort.