Setting the policy to True turns spoken feedback on at the sign-in screen. Setting the policy to False turns spoken feedback off at the screen.
If you set the policy, users can temporarily turn spoken feedback on or off. When the sign-in screen reloads or stays idle for a minute, it reverts to its original state.
If not set, spoken feedback is off at the sign-in screen. Users can turn it on any time, and its status on the sign-in screen persists across users.
Note: DeviceLoginScreenSpokenFeedbackEnabled overrides this policy if the former is specified.