The Magical Island - Visual Map

So now that I've moved towards the idea of designing an Interactive Magical Island (just to clarify, not one in the sea, a kitchen one). What shall it do and why...

Scenario One

A group of housemates are sitting around the island having a cup of coffee and a snack. The table detects where each person is through sound waves and creates an abstract visual map on the surface. As people are talking, ripples start to appear on the surface coming from the direction of where people are talking. If people are closer, louder etc, the ripples will be stronger and more distinct. 

By placing objects on the surface, this causes the ripples to bounce off it. If it is a heavy object, it causes a faster, stronger deflection than a smaller or lighter object,

I'd see something like this being made using sensors which communicate through arduinos to processing to create the graphical content - possible something like the video Flight 404 did for Goldfrapp.