Microsoft Windows
Get the extension at the Extensions web site. Open the extension with the LibreOffice or Apache OpenOffice program. Approve the extension. Restart the program.
Built-in Speech
The Read Text Extension uses a script for speech synthesis by default. To reset the extension to the default settings, type random characters in the Read with an external program box and click OK. The extension will display an error message and reset all the settings to their defaults.
Windows Default
Users of supported Windows releases can download and install Desktop language packs at no additional cost. Many of the languages include a local voice for speech synthesis. Instructions are available at the Microsoft Support site.
New systems generally include voices in English, but the system might include voices with different languages or local accents depending on the region and the manufacturer's default setup resources.
eSpeak
Install eSpeak. When you install the program, a dialog will ask you to select some voices that will be supported with applications that use SAPI5. Supported languages include Afrikaans, Albanian, Armenian, Cantonese, Catalan, Croatian, Czech, Danish, Dutch, English, Esperanto, Finnish, French, German, Greek, Hindi, Hungarian, Icelandic, Indonesian, Italian, Kurdish, Latvian, Lojban, Macedonian, Mandarin, Norwegian, Polish, Portuguese, Romanian, Russian, Serbian, Slovak, Spanish, Swahili, Swedish, Tamil, Turkish, Vietnamese, and Welsh. Once the SAPI5 voices are installed, you can use the default dialog as shown above to select one of the eSpeak SAPI5 voices. If you want to try out different voices, you can call the espeak program directly:
Select some text
Show the Read Selection dialog with Tools → Add-Ons → Read Selection...
Select Read the Selection with another program
Browse to the path to the Espeak application - C:\Program Files\eSpeak\command_line\espeak.exe
In the command box, enter -v english -f "(TMP)"
Click OK
Festival
Instructions for compiling Festival for Windows are available at the Festival website.
Python and SAPI5
Python is a flexible and powerful scripting environment. If you install Python on your computer, you can use it to connect to the Windows native SAPI5 text-to-speech engine.
WScript and SAPI5
WScript is an easy to use scripting environment for Windows computers. If your Windows computer has SAPI5, you can use WScript for text-to-speech.
Use with Web Applications
Web applications let you do on-line translation, read multiple languages and try different voices.
Select some text
Show the Read Selection dialog with Tools → Add-Ons → Read Selection...
Select Use a web application.
Choose or enter a web address with the appropriate parameters. - https://translate.google.com/?&langpair=auto|(LANGUAGE_CODE)&tbb=1&ie=&hl=(LANGUAGE_CODE)&text=(OOO_WEBTEXT)
Click OK
For more information about web applications, read Use With Web Applications.
Other Options
Microsoft - Windows 10 Narrator, Third Party Applications
Customize
You can use different external applications or websites to speak different languages or translate text. If you want to view the dialog to change settings, use Tools - Add-Ons - Read Selection...