@aral Thanks. Yes, it's sound absorbing. I bought it at the local hardware store, the brand of the panels is #FibroTech.
[1] https://www.bauhaus.at/akustikpaneele/fibrotech-akustikpaneel-basic/p/28453299
[2] https://fibrotech.com/en/product/fibrotech-basic-acoustic-panel-22-x-605-x-2440-mm/