You could do OCR with a barcode scanner type device - but even then OCR is very 'hit and miss'.
Agraham already did a Text to Speech device library here :
http://www.b4x.com/forum/additional-libraries/1250-speech-library-device.html#post6582
What I'd recommend if you're trying to do this is have the text you wanted them to be able to hear embedded in like a QR code or datamatrix barcode, then instead of the issues you'd have with OCR, they'd scan one thing and hear the embedded text.
With OCR - they'd need to pass the scanner/camera over each letter ... it becomes very problematic.
You could use Agraham's barcode library for the PC -
http://www.b4x.com/forum/additional-libraries/4062-barcode-generation-library.html#post23517
1) develop a PC app to take a text field and convert it to a barcode.
2) print the barcode
3) have a scanner/camera device read the barcode, then take the received data and use the text to speech library.
The most expensive part of the whole thing would be the barcode readers - the cheapest ones to do this sort of task that could use B4P that my company sells range from like $500 - $750 (but these are industrial devices designed to take a beating...)...
Agraham did write a barcode reading library for devices with a camera with the quickmark application installed - so you could try that too if you had some cheaperish / used devices...
http://www.b4x.com/forum/additional-libraries/4044-quickmark-1d-2d-barcode-reader-library.html