It is my understanding that they can learn to talk, but it may be harder to understand what they say as the are not as clear as some of the other species when and if they talk. This is based only on what I have read from people who have them, I have no personal experience with them.
I am pretty sure they have the same 'voice apparatus' as the other species of parrots but I doubt they are 'talkers' (most aviary species are not for the simple reason that they don't have that much interest in human beings to begin with).