The Talk Back feature on Vizio TVs is a text-to-speech feature that narrates the text displayed on Vizio TVs. This works for all kinds of texts that the TV displays including the menu functions, settings and apps except with external devices or streaming apps. The voice will be off on your Vizio TV as soon as your turn off the 'talk back' feature which you can usually find under the accessibility settings on your Vizio SmartCast TV.