absorber

Hi folks, I have a question about acoustics for you. Yesterday I attended a meeting with other kid's parents in a school canteen (cafeteria in USA? ). I took a picture of the ceiling: I'm assuming they have an acoustic purpose from now on. It seems a low density foam of about 4 cm thick...

I'm in contact with a company who produces panels made from PET (Polyethylene Terephthalate, not domesticated animals). They send me their performance data for a 15mm (0.59 inch) thick panel… Does the low frequency absorption seem unusually high to you too or am I misreading it?