I've posted on several help topic pages and I opened a ticket with the Accessibility department but my problem wasn't resolved with a satisfactory solution; just work arounds. I'll say it again here.
System Preferences>Accessibility>Spoken content>Speak selection>"options" doesn't have a way to control which voice is used. The computer randomly chooses the "speak selection" voice. I didn't get a single one of the random voices I wanted. (I know how to add and remove system voices and the computer uses a voice I don't even have selected in the "system voice" window sometimes.) "Speak announcements" has a selection tool under "options" and it works with the selected voice. What is odd is that both "speak items under the pointer" and "speak typing feedback" don't have a way to pick the voice used under "options" but they both use the same voice that is selected on the "system voice" drop down menu under "Spoken content". For some reason "speak selection" doesn't register the chosen voice under the "system voice" drop-down menu.
This is an issue with a 2014 macbook pro running big sur 11.1. Troubleshooting included a clean install of big sur 11.1, a safe boot, and a NVRAM reset. When I got connected to the Accessibility department they said that changing "speak selection" voice wasn't an option and they gave me a few helpful articles for a work around that I may try but I don't really want to use the VoiceOver command or the Voice Control commands because VoiceOver is too cumbersome and you can't customize what is said and Voice Control makes me speak commands and I prefer to be mute when I'm on my computer and listen instead of speak. Plus, if you throw VoiceOver and Voice Control together you are going to overload you computing capabilities and be unable to operate anything that is processor intensive. Also there are sure to be cross talk issues and I don't want a headset.
The staff that I remember names of were Aubrey and Nathanael and they were both excellent resources to work on this problem. They were polite and quick, I wasn't aware of the 24/7 chat support until now and I've got to say; at least apple directs you efficiently with their tech support unlike other manufacturers that have horrible support wait times and worthless tech communities.
But all that being said I would like to voice my disappointment that my solution will likely just bog down my computing capabilities and I would like to urge the engineers to make "Spoken content" fully functional such that the community is satisfied with the updated product. I just found out about this feature but there are some other not so satisfied users out there.
Currently I'm running the "Spoken content" option by using "speak items under the pointer" and "speak announcements" because it doesn't overload my mac and I can run streaming services while working on my art projects. But when I want to have the computer read a long text to speech entry "speak items under the pointer" fails to consistently read long passages. I would like a better long passages solution than VoiceOver because like I said, it just kills the ability to multitask on a laptop.
*Drops mic*