I know that Mac OS X 10.12 (aka Sierra) was been out for a while, but I’m still getting used to some of the subtle changes. With Siri’s voice recognition technology now included as a standard feature, it seemed odd that the list of synthesized voices that could be installed and played back in earlier iterations of OS X were nowhere to be found. Or, at least that’s what appeared at first glance.
Text-to-Speech voices are now available when you click the Accessibility pane in System Preferences. The new location is where you’ll have access to your installed set of synthesized voices that were playable when running older versions of Mac OS X. The attached screenshot depicts how the Apple developers merged the old Speech features into the Accessibility pane.