Note: The method requires Registry editing. There is a way, however, to unlock all Windows 10 text-to-speech voices so that they become available to any program or app that uses the voices that Windows provides. The third-party program Balabolka displays only three voices that you may select even though you know that more are available on the device: frustrating.
The screenshot above shows how many voices are available when you select the voice picker in Narrator. When you open a third-party program that uses voices on the Windows PC, only some of these are provided.
If you open Settings > Ease of Access > Narrator and select the 'choose a voice' menu there, you get a list of voices that are available.
