It's important to indicate the language or languages within your document for a screen reader to read it properly. During setup of Microsoft Office, you likely specified your default language as English. If you would need to change the default document language or add additional languages, within a multi-language document, you can do this under the File menu. Select Options from the list on the left navigation. It's at the bottom of this list within Word 2016. In the Word Options dialogue box that pops up, select Language from the navigation list on the left. From the drop down menu below your Editing Language box, where it says, "Add additional editing languages," click on the drop down arrow to expand the menu and select English (United States). Then, click the Add button the the right of the drop down menu. If you need to add more languages than English, select them from the box also, and click on the Add button. Click OK at the bottom of the dialogue when you are finished.
The default settings in JAWS 17 automatically detects when the language changes within a Word document and will start reading in the new language. NVDA will do this when its voice synthesizer is set to its default eSpeak NG. To make sure NVDA's synthesizer is set to eSpeak NG, find the NVDA icon in the system tray (Windows). It looks like an N with a curved ascending arm as seen below.
Right click on the NVDA icon, and select Preferences to expand its preferences menu. Within the preferences menu, select Synthesizer.
Select the first option for synthesizer to set it to eSpeak NG. The Microsoft Speech API version 5 sounds more pleasant, but won't automatically switch the languages its reading when the language changes.
I'll attach a multi-language Word document below in case you would like to practice with it.
If you find that a screen reader automatically switches to a foreign language when it should not have, you can select the line of text that it isn't reading properly, and go under the Review tab, click on Language in the ribbon at the top. Select "Set Proofing Language." From the Language dialogue box the opens up, you'll see the incorrect language highlighted. Scroll to find the language you want, such as English (United States), select it and click OK at the bottom. The screen reader should now read back the line in English, if you chose English. This case really did happen with the practice syllabus you'll work on for your assignment in this module. For some reason, when JAWS and NVDA reached the line starting with "Prerequisites," it started reading in German. That could throw your audience off track!