Is it possible to launch preferences pane with Accessibility/Speech open on macOS Sierra? For accessibility I am aware you can do that with x-apple.systempreferences:com.apple.preference.universalaccess. I am also aware that most tabs in Accessiblity pane can be opened when launched, but there is no document for whether it is possible for Speech tab on Sierra. This is the most comprehensive link I have found thus far: https://macosxautomation.com/system-prefs-links.html, but it predates Sierra and speech belonged to different pane then, so it is listed but that link isn't useful.
You're looking for x-apple.systempreferences:com.apple.preference.universalaccess?TextToSpeech
The anchors for the pane can be retrieved by opening it and then querying the app with applescript:
tell application "System Preferences" to get anchors of current pane
Which returns:
"Keyboard"
"Dwell"
"Captioning"
"Seeing_VoiceOver"
"SpeakableItems"
"TextToSpeech"
"Hearing"
"Switch"
"General"
"Media_Descriptions"
"Mouse"
"Seeing_Display"
"Seeing_Zoom"