Audiobooks Curiosity

Sly B and I (and Sly B's mother) are big consumers of audiobooks. It started, I think, with the Harry Potter books, which in the U.S. at least are read by Jim Dale. Dale does voices and really makes the books a lot of fun. We were hooked immediately. Since then, we have accounts at audible.com and always have a bunch of books in the queue.  (Also among my favorites are the James Lee Burke Dave Robicheaux books narrated by Will Patton - great, great listening experiences.)

I am usually reading one book the old fashioned way, and listening to another. Currently, I am reading The Etched City by K.J. Bishop, and am listening to Feast of Crows Book 4 of The Song of Ice & Fire by George R. R. Martin (which is a re-read for me).  

What I wonder today is this:  why, when there is a series of books (like the Martin series), would the audiobook reader change? I have spent HOURS listening to the first 3 books and really loved the reader. Now, in book 4, I have to get used to a whole new voice (this guy is a very stage-actor type) who pronounces the names differently.  Ugh.  I don't like it.