#Sound absorption synthetic fiber sheet PET/PETP polyethylene terephthalate 100% sound collection outside the room. Echo reduction in the non-flammable room can be applied to both ceiling and wall panels. The PET/PETP polyethylene terephthalate 100% sound absorption has a sound absorption value (NRC) = 0. 9) 90% Soundproofing (STC) = 6db. Resist heat (R) = 1.238 m' K/w with thermal conductivity (K) = 0.041 W/m'k, reducing the heat in the room by 10 degrees.