Such a choice is appropriate in all cases where it is lokked for an absorbing lining having both a very good absorption factor, with a minimum thickness, with minimum a cost and with minimum installation costs. The lining type "Broadband Compact Absorbers" - in English abbreviation BCA "Compact Broadband Absorbers", in German BKA "Breitband Kompact Absorbern") is plane: it is particularly appropriate for testing rooms such as anechoic or semi-anechoic rooms (including: aero-acoustic wind tunnels), particularly in the automotive industry.