For both speech recognition and speech synthesis to use a language, install the language and select it. The language is installed via windows language settings. If your computer has the language installed, you can select it from the windows speech recognition and speech synthesis settings. The settings can be found in the control panel - and for speech recognition selected in the appropriate control configuration in ARC. 

Here's more help from Microsoft regarding Windows speech recognition languages: https://support.office.com/en-us/article/how-to-download-text-to-speech-languages-for-windows-10-d5a6b612-b3ae-423f-afa5-4f6caf1ec5d3

*Note: You had selected "Artificial Intelligence -> Dialog Flow" as the control connected to this question. We edited the question and connected it to "Audio -> Speech recognition".

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