Sound to Create Atmosphere 

Emotion, atmosphere, scene setting, voice acting, details to the scene are all essential to animation as without them your experience will be incomplete. Visuals only capture your attention for a moment where as sound can keep your attention for longer. A real life example would be the radio which people still like to listen to even though there are no visuals to see with it. If sound is used effectively it adds texture to any narrative and retains the audiences attention for longer.