sound proofing folding walls stc rating SOUND PROOFING (quiet space without any noise) The operable wall forms an automatic sound proofing seal against the two end walls without the need of any manual intervention. The end seals shall act in such a way as not to come into contact with the end walls while the operable wall is in motion. The end seals shall leave a joint between the sound proofing panels and the end walls of no more than approximately 1” (25mm). Seals that rub or brush against the end walls are not acceptable. Once the wall reaches the fully down position, the end seals shall activate automatically. The key switch must be held for the duration of the operation.