Hello,
To me, Kurzweil 1000 is one of the best learning tools ever made for blind and visually impaired people. What I dislike about it is that it converts some file formats such as docs or PDF instead of reading and editing them.
In terms of OCR accuracy, I have a mixed feeling about it; sometimes it does a really good job; other times it ruins everything. I compare it to ABBYY Fine reader, which is my primary application for scanning and converting text to digital formats. I've had the chance to try all the OCR applications which specialise in scanning and converting text to digital formats from ABBYY Fine reader, to Kurzweil 1000, Openbook, Nuance Omnipage, Read Iris, and none is as reliable as ABBYY Fine reader. It supports a great number of languages with dictionaries and thesauruses which contribute to the overall recognition results. That's what I'd recommend to anyone who needs to convert books and documents to digital formats.
Getting back to Kurzweil, What I like about it is that it has a very unique reading pattern. Kurzweil will indicate when you have reached a new chapter as the reading pauses will change from when you are reading consecutive lines of text. It will also create a different pause when you begin reading a new paragraph, as well as when you finish a page and jump to the other. All these indications, of course, will be given when you read continuously.
Anyway, to disable built-in speech in Kurzweil 1000, you go to settings> configuration and navigate with tab until you hear "Active speech is enabled". Change it to "disabled" with the arrow keys and click ok. Don't forget to save the settings in default before closing the program.
Hope this helps.
Cheers!

@afrim
Thanks so much for your reply!
If you'd help me with the following questions I'd be grateful again:
1. Is there some kind of tutorial for Kurzweil1000?
'cause I get confused and don't know how to use it.
2. As I disabled that Active Speech the built-in speech disabled but it won't read the text with the F5 key.
3. NVDA doesn't work in the editbox as it's supposed to.
I can't read with the arrow keys.
In other words, is it possible to read with our own screen reader?
4. In the recognition settings it seems it's using fine reader engine 11 so what is the difference between fine reader and Kurzweil1000?
5. If it's using that engine does that mean we could use all of the languages in fine reader here also?
6. Speaking of ABBYY Fine Reader: Could you please give a few tips to get started with that?
I've heard there are some languages as addons.
How to install those?
I've got both ReadIRIS and ABBYY Fine Reader also. So any tip would be apprecieated.
Really really sorry if I asked so much.

Sorry for bumping this topic up but I've got another question which I'd be very grateful if someone help me.
Today I opened a secured pdf with kurzweil1000 which needed a password to be opened.
I pressed "Cancel" button and it tried to convert the pdf to image using Adobe Acrobat Reader which I have installed and Convert it to text.
The question is: Could I do that with non-secure pdfs?
I mean forcing kurzweil1000 to convert it to images first and then convert it?
Because the resulting text was slightly better.