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I use both Jaws and NVDA while reading Kendal Books.
Now with that being said, there are some Books that are not made the same, and those either will not read at all, or Kendal itself will use a Voice, a not very good voice, to read the Book.
I have not yet figured out what to do about those books that either do not read at all, or Kendal reads it with it own voice.
maybe the folks at Amazon's Customer Service for those with Disabilities can help.
As slim as the Chances of this happening, it never hurts to give it a try.