I was once part of an audio book venture that created a book reader app and and associated library application library that was specifically designed to be used by the blind and severely disabled. It actually met all its goals in regards to usability.
You must be from the future, because if there is a silver-bullet book reader solution for blind people, I certainly couldn't find one for my half-blind mother.
Currently, there is the audiobook reader provided for free by the Library of Congress. That reader is great in terms of physical interface design, but it's limited only to books that have had professional voice actors read them.
And then in terms of text-to-speech technology, the best technological solution out there is currently Ivona (now owned by Amazon), but despite all the awesome progress this technology has made over the years, it still isn't good enough for most blind users who want a book read to them for leisure.
So the company took it to the largest national organizations to get their seal of approval for it. The company was turned down by all of them because although application interface years ahead of any other application in regrades to the blind and severely disabled, their words, it did not accommodate the deaf. An audio book application that did not accommodate the deaf.
I'm not sure what you mean by "the largest national organizations" out there, and why you would even need their seal of approval in the first place, but if your venture was looking to get cash from them, or get some kind of exclusive endorsement from them, for what seemed like a commercial venture, it doesn't really matter the reason they gave you for that denial.
There is currently no perfect usable book reader for the blind. It doesn't really matter if the blind person is deaf, or not. For instance, my mother certainly wasn't deaf, and she certainly loved books, but there really wasn't a book reader solution that was satisfactory to her.