Already been done; a friend of mine Chris Rawlins has effects with sound reading and has spent much time recording material for a similar release. It does not mean you should not think of doing something similar although I will tell you it is difficult to get a good sound.
It is a strong tool to have, releasing audio of sounds is almost impossible if you are not well versed in the subject for example the number six, sounds like zero.... The number four can sound like a seven (if they put the little dash through the seven).
There are a lot more similarities than you would expect and there are also tricks for double numbers. Which I shall not go into but you can see how it would be problematic.
Already done? Interesting, can it be bought somewhere, do you have an URL?
About the sound quality, i've got that covert. A friend of mine owns a sound studio thus giving me the equipment needed. Same with video as I own that equipment myself.
About the problems, yes, that will be a challenge. Do you have any tips or directions to sources how to tackle such issues? I guess pencil + sound reading together would help. Also just guessing but with a backup could work as well "you didn't write a 7 did you? (if yes) yes, i thought so (discart billet) / (if no) No, that's why i wrote down a 4 (show billet)"
Also, what would be preffered? a package of video's and some instructions or an app that can be views on mobile phones and in your browser?