It looks to me like the drapes are just drawn to the window sides. I notice the treatments appear to cover different frequencies, due to their various sizes. They look like they are all absorbers, but that can be deceiving, as some companies make diffusers that look like the typical absorbing panels and traps. I wouldn't venture to assume whether there is too much treatment without hearing the resulting sound or seeing the rest of the environment. Hell, I've got six bass traps in my listening space and have phenomenal bass, IMO. I tried eight, but that was too much, as was easily heard by the bass becoming too loud and one dimensional (thumpy, one note).