Usually, fibrous materials with porosity can dissipate the energy of the sound wave penetrating them, so can be the useful sound absorbing materials to reduce the noise in the vehicle. The fibrous materials have been used for the various types of automotive components as the sound absorbing materials, which can be placed close to the noise source, in the noise paths and near the receiver such as passengers. Although all materials can absorb a little amount of sound energy, the term “acoustical material” has been primarily applied to those materials that can provide the higher sound absorption performance above the ordinary levels. One of the examples of fibrous acoustic materials for automotive components is the sound absorbing felt composed of the fibers which have the several characteristics such as the material type, the cross-sectional shape and the fiber density (can be expressed as denier) related to the sound absorbing performance. Therefore, we have studied about the acoustic materials using the hollow fiber to reduce the material weight as well as to improve the performance. Compared with the normal fiber, the hollow fiber has the larger specific surface area to be contacted while the sound wave propagated through the acoustic materials. In this study, porous fibrous materials using the hollow PET (polyethylene terephthalate) fibers are developed and evaluated to meet the acoustic requirement of the current automotive components, which can be reduce the weight and achieve the higher acoustic performance.