Measurements of folding walls (discussion in connection to the revision of ISO 354) recently introduced a sound absorbing folding wall at We are very happy with that and it is the company “Quiet solutions” that provides this unique wall. However, since this product was introduced we realized that there is lack of guidelines regarding measurements of these products. When a folding wall is mounted as a partition it is not only an efficient high frequency sound absorber but also a low frequency sound absorber of importance. Therefore the team means that folding walls should absolutely NOT be measured lying close to the floor in the reverberation chamber, it should preferably be mounted in a test opening. By testing it as a “normal” wall absorber its low frequency sound absorption is not registered. Hence, the sound absorption characteristics are not at all according to the real performance when it is mounted in a building. When the wall is mounted in real rooms the products low frequency sound absorption is always present. And low frequency sound absorption is very important for the final room acoustic in a room.