What would you treat?

[Keith_W]

Ahhh. Well it would appear that spike is at 126Hz and not 160Hz.

This is what it looks like in RT60 decay.

To be honest it looks like a room mode to me. I am not sure what it is about its appearance that suggests that it is a physical resonance, i.e. something rattling. Could someone explain?

The idea of the felt pads is to prevent the frame from banging against the wall. It does not have any acoustic effect otherwise.