Recently, high story apartments are common to solve a housing problem especially in major cities. Apartments are considered as clean, sanitary and convenient to live. However, There are some problems because residents share walls, floors and ceilings with other people. Thus, the residents are often disturbed by neighbours since sound travels the building elements. Especially, impact noise through the floors causes the many complains. And so, it has been drawn attention to isolate by the impact sound. The purpose of this study is to analyze the characteristics of vibration response of 12-type void slabs in the improved void slab by impedance method, and is to find the best improveds void slab on the 12-type void slabs.