Hi MehdiN,
Thank you for posting your query on Microsoft Community.
As per the issue description you are willing to add Persian/Farsi language for Windows Speech Recognition. I would like to inform you that Persian/Farsi language is not available for Windows speech recognition. For more confirmation I would suggest you to check the article mentioned below.
Language Support (Speech Recognition)
You may try the steps provided in the thread mentioned below and see if it helps you to add Persian language.
Speech Recognition for Persian Language
Note: Using Third Party Software, including hardware drivers can cause serious problems that may prevent your computer from booting properly. Microsoft cannot guarantee that any problems resulting from the use of Third Party Software can be solved. Using Third Party Software is at your own risk.
Hope the information provided is helpful. Do let us know if you have any more concern related to Windows. We will be more than happy to assist you.
Regards,