Since OneCore has been removed, it is technically replaced with the cloud services counterpart.
To setup this service, you are going to need a Microsoft Azure account, once you have an account head over to portal.azure.com
- Click Create a Resource
- Search for Speech in the search box, and pick it
- Click "Create"
- Enter a name, this must be unique, for example, I just called mine nate1280-tts
- Pick your subscription (you may have to start the free trial, or if you have already done this, your service will be Pay-As-You-Go)
- Pick your location, I use East US, this location can effect what voices are available for you.
- Pick your pricing tier, you want to pick the F0 Free Tier
- Pick your resource group, if you do not have any setup, click "Create New" and add a new one
- When all done, click the "Create" button at the bottom.
- This takes a few moments to get setup, once its done, go to the newly created service and click on "Click here to manage keys"
- You'll want to copy "KEY 1", and paste this into the subscription key box in Twitch Speaker
- Copy the location, and paste it in the service location box
- Click the Azure button to enable the engine and be sure to save your settings.
- The free tier allows for 5 million characters per month with standard voices, and 500k characters per month for neural voices.
There is an option/ability to setup your own custom voice, but that is beyond the scope of this.