“In a busy setting, do animation and sound in particular distract viewers from absorbing your messages, or do they help to draw attention? How much is too much?”
Animation and sound can definitely distract viewers from absorbing your message. Sound, in particular, can prevent people from even hearing themselves speak, turning off the desire to receive any new information and essentially creating information overload. We have no sound attached to our signage, mostly due to the large numbers of people that pass by. Sound would be lost in the shuffle.
Regarding animation, I sat in on a seminar at one of the prior DSEs, and one major point I learned was that gentle motion caught the eye, while rapid motion would render that information much less useful. In the example, text was being pushed gently in the direction that the eye would naturally follow, so the message seemed to stand out against the rest of the noise in the environment. I’d never considered it before but have remembered it since, as one of the lessons learned on how to use motion effectively.
With that said, it depends on your goal. Animation and sound can be such a huge boost to grabbing attention anywhere. I would recommend evaluating your goal, and taking the time to understand the environment well, including any unintended consequences of adding that sound or animation. Just like in a PowerPoint presentation, sometimes it can be too much if it distracts from your message. The appearance of less can be more powerful!