So is it damping or deadening only joking I’ve used both terms and not even thought about it, but when your right your right.

I think the material which ever you chose has to convert the in coming sound energy into another form of energy, heat.

In order to measure the energy exchange you measure the vibration of the panel before and after and this gives you the loss factor.

This is from memory, we had visit from the man who started dynamat, so since then I’ve used there products.

If I made any errors I apologize in advance.