Apple MacOS
Get Read Text Extension
Click the Download Extension button at the official LibreOffice or Apache OpenOffice extensions site. Open the LibreOffice or Apache OpenOffice program. Choose the Tools → Extension Manager... menu. Click the Add... button. Use the file dialogue to choose the extension file in the downloads folder. Click the Approve the extension. Restart the program. By default, the most recent version of the extension uses a script to determine the best voice for your language and region.
Make sure that you down the most recent release of the extension from the official LibreOffice or Apache OpenOffice extensions site. For details on new releases, see the most recent commits on GitHub.
Use Read Text Extension
Click the Read selection button to use the extension. The first time you use the extension, it shows you a dialogue with speech synthesis options.
"(SAY_APPLESCRIPT)"
Click OK to try the default options. If you are satisfied with the default options, click the Read selection button again and uncheck the Always show this dialogue checkbox, then click OK.
Improve Voice Quality
You can install high quality versions of some system voices. See Apple Support → Change the voice your Mac uses to speak text → Add a New Voice.
Use Read Text Extension with a specific program
You can start executable programs directly when you click the Read selection button. For example, you could select a specific voice or save the speech as a sound file using a command line speech synthesis manager called say. Find out more about the say command at the say(1) OSXmanual page.
Select some text
Show the Read Selection dialog with Tools → Add-Ons → Read Selection...
Select Read the Selection with an external program
Browse to the path to the say application - /usr/bin/say
To speak the text aloud, enter in the command line options box: -f "(TMP)"
To save the text as a sound file in your home directory, enter: -f "(TMP)"-o "(HOME)(NOW).aif"
Click OK
Additional system voices in many languages are available from independent vendors or may be included as part of an accessibility package. To use a specific voice with say, enter the name of the voice in the command line options box: --voice=Alex -f "(TMP)".
VideoLan VLC
VideoLan VLC is is a free and open source cross-platform multimedia player and framework that plays most multimedia files as well as DVDs, Audio CDs, VCDs, and various streaming protocols.
You can use Read Text Extension with VLC to create compact audio files like OGG and OPUS.
The VLC desktop application is available for Apple Silicon and Intel computers. Be sure to download the desktop version that matches your computer.
When you use VLC, Read Text Extension exports do not include metadata like author, album and track information.
Example
"(SAY_APPLESCRIPT)" "(HOME)(SELECTION_LANGUAGE_CODE)/(NOW).opus"
Use with Web Applications
Web applications let you do on-line translation, read multiple languages and try different voices. To find out how to set a different browser like Firefox or Chrome as the default, read this article from the Apple Knowledge base. You will still be able to use your old web browser by clicking the icon, but external programs will use the browser you selected as your new default.
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
Have your Mac speak text that’s on the screen
Apple Accessibility - Accessibility
Customize
If you want to view the dialog to change settings, use Tools - Add-Ons - Read Selection...