Great question, William! Looks like Voice Interaction function is only available for the KS9800, KS9500, KS9000, KS8000, KU7500, and KU7000 series models (2016 UHD TVs).
To set up voice interaction please follow these steps:
Turning the TV's verbal response (voice) On/Off:
Home > Settings > System > Expert Settings > Voice Interaction > Voice Feedback.
Selecting the Voice's Gender:
Home > Settings > System > Expert Settings > Voice Interaction > Voice Gender.
Thanks for being a customer! ^Mel