As people did not have telephones and television right after the tower of Babel, it was bound to happen that accents would shift.

Depending on the speech impediment of the most popular townsman, the accent shifted. These changes in pronounciation occured on areas as small as 20 miles.

However, if one compares all these changes in languages you see that a lot of IE languages have had a change in voiced > unvoiced consonants. B > P, D > T, G > K.

If you bring to mind that a lot of people in the old days, just like nowaydays were just too darn lazy to bother with the right pronounciation, and added with these changes and forgetting the introduction of the written standards, you might be stunned to see how easy Sanskrit is to read.

What I'm saying that: If you know the tricks: all IE languages are remarkably similar. Except Finno-Ungarian and Bask...they're a riddle to most linguists.