An AppleScript to switch the Text-To-Speech voice from Daniel to Ting-Ting and vice versa. I use it because I often have to switch between English and Chinese TTS. I found this script online and modified it.

OSX Switch TTS Language

tell application "System Preferences"
	activate
	reveal anchor "TTS" of pane "com.apple.preference.speech"
end tell
tell application "System Events" to tell process "System Preferences"
	tell pop up button 1 of tab group 1 of window 1
		click
		delay 0.5 -- without this the value was sometimes "Loading Voices…"
		if value is "Daniel" then
			click menu item "Ting-Ting" of menu 1
		else
			click menu item "Daniel" of menu 1
		end if
	end tell
end tell
quit application "System Preferences"