ANCUTA ELENA TIUC, OVIDIU VASILE, HORATIU VERMESAN, PLATON MIHAI ANDREI SOUND ABSORBING INSULATING COMPOSITES BASED ON POLYURETHANE FOAM AND WASTE MATERIALS The acoustic comfort includes the protection against noise and it is closely related to the sound absorption concept. This paper presents an experimental study on sound absorption coefficients, for some composite materials: waste materials (rubber crumbs, textile, flax fibers) mixed with rigid polyurethane foam as binder. The composite materials were characterized both acoustically (sound absorption coefficient) and also in terms of heat transfer (thermal conductivity). The acoustic absorption coefficient was determined using the impedance tube and the influence of structure of these materials on the sound absorbing properties was analyzed. The experimental results show the sound absorption performances of some composites based on recycled waste materials, thus promoting environmentally friendly solutions.