Parametric Study on Floor Impact Sound with Design Factors of Layers Composing a Floating Floor in Multi-Residential Buildings

The purpose of this study is to examine the main factors in the control of floor impact sound with various design and construction methods of a floating floor. The factors that were considered include the thicknesses of the resilient and mass layers and construction order of the lightweight concrete to secure a floor flatness. The results, which were measured at mock-up housing units, showed that increasing the thickness of the resilient layer loading the same mass is effective in controling the amplification due to mass-spring-mass resonance at 63 Hz. The sound reduction by increasing the thickness of the cement mortar from 40 mm to 80 mm was analyzed using 6 dB of a bang machine, 8 dB of a rubber ball, and 8 dB of a tapping machine in the single number quantity. According to the construction order of the lightweight concrete, the reduction effect in the single number quantity was similar to each other. The relationship between the floor impact sound reduction and different heavyweight impact sources showed a high correlation coefficient of over 0.9 at below 63 Hz, and a relatively low correlation coefficient at 125 Hz ~ 250 Hz. This result indicates a different subjective response related to floor impact sound reduction with different heavyweight impact sources.