In this post, daily writing tips explains why it is difficult today to find a standard Amarican prononciation:

Now, however, a doctrine of political correctness inhibits the teaching of standard pronunciation with the result that the media has become the final arbiter.

And the post list some examples of prononciations that were considered as non-standard: 

• Plurals of nouns like life, knife, and wife: It is possible to hear wifes instead of wives 
• House and houses:  noun house /hous/ and its plural houses /houz iz/. Until fairly recently, the pronunciation of the plural houses with a soft s /hous iz/ was a nonstandard regionalism not even mentioned in the dictionary.