This study investigated the noise reduction effect according to the structure of the sound-absorption and insulating materials in order to maximize the noise reduction effect in various noise environments. For this purpose, the transmission loss according to the change in hole size of the performated plate in sound-absorption and insulating board was predicted using an CAE model. The sound-absorption and insulating board was modeled and the computation of the transmission loss was performed after applying the physical properties and boundary conditions. The pure sounds of 32Hz to 4,000Hz were generated, and the analysis was performed by changing the diameter and pitch of the perforated plate. It was confirmed that the influence of the diameter and pitch of the perforated plate is closely related to the structure that make up the sound-absorption and insulating material. In order to effectively reduce the variously changing noises, it is believed that a method of improving transmission loss for each frequency band of interest is needed by changing the structure of the sound-absorption and insulating material so that the diameter and pitch of the perforated plate can be changed.

PURPOSES : This study is to compare sound transmission loss(STL) value depending on the four kinds of materials, PC(Polycarbonate), PMMA(Polymethyl mathacrylate), PE(Polyethlyene), PP(Polypropylene), and two types of structure, single layer and double with vacuum layer, of soundproof panel. METHODS : With four sorts of polymer material, the specimens were made as various structures, 4 mm and 8 mm of single soundpoof panel and vacuum layered 4 mm of one. The experimental condition and procedures were complied with authorized process test, KS F 2808. RESULTS: STL of single panel made of PC were the greatest followed by PMMA, PE, PP regardless of the thickness of panel, However, STL of PMMA panel began to decrease around 2500 Hz and reached the lowest value among others in 5000 Hz. Vacuum layer soundproof panel showed good performance in more than 2000 Hz. Only vacuum layer panel made of PC presented resonance frequency at 800 Hz while that of other vacuum ones at 1000 Hz. CONCLUSIONS: According to results of single layer, it was found that single panel functioned as the theorical way we expected in terms of surface density. That trends were blurred as the panel got thicker. And it was suggested also that vacuum layer panel performed well at high frequency, more than 2000 Hz.