I had some fun poking at Bane's mumblings in my conversations with friends but I personally don't think it was as big a problem as other people thought it was. According to the link below, it seems that Nolan did end up enhancing Bane's voice. I guess it must have been Warner forcing him to do it.
http://www.blackbookmag.com/movies/upda ... ng-1.43693
http://collider.com/dark-knight-rises-b ... ed/135038/
http://www.blackbookmag.com/movies/upda ... ng-1.43693
http://collider.com/dark-knight-rises-b ... ed/135038/