Reduction of Heavy-weight Floor Impact Sound by Granular Materials on Ceiling

It is well-known that constructing ceilings below a slab increases heavy-weight floor impact sound. In order to prevent the sound from increasing, we usually make the slab thicker or adopt a floor finish having excellent sound insulation performance on the slab. The weight increase of the slab and finish affects the structure of the building such as pillars and beams. Thus we think that installing granular materials on the ceilings decreases the heavy-weight floor impact sound without making those elements of building heavier. In this study, we have investigated the effect of the granular materials on the heavy-weight floor impact sound. In the laboratory, we measured the heavy-weight floor impact sound for the combination of the ceiling and the floor with the granular materials which were made from the recycled resin and were packaged in bags. From those measured results, we have found the following: (1) The heavy-weight floor impact sound is reduced by about 10 dB at 63 Hz by installing the granular materials of the same surface density as the 9.5 mm thick gypsum board. (2) The effect of granular materials depends on the ceiling board thickness and floor finish.