Effect on the sound insulation performance of flush doors by aperture conditions between door and doorsill

Recently, the sound insulation performance of the flush door in apartment unit has been degraded due to the design of barrier-free which has an aperture between the lower part of door and floor level. In this study, we measured and compared the sound insulation of 8 flush doors without doorsill for barrier-free and 5 flush doors with doorsill in apartment units. And the measured values were compared with the predicted values by theoretical sound transmission. The results were summarized as follows; First, the average aperture width of flush doors without doorsill was surveyed 6.4 mm. Second, the single number quantities (DPjW, the weighted level difference referred to Korea Standard F 2809) of the flush doors without doorsill and with doorsill were evaluated 20-25 dB and 28-31 dB, respectively. When the apertures were air-tightly sealed, the single number quantities of the flush doors were increased up to 31-34 dB. Third, the measured values (DPjW) were good agreement with the predicted values in condition of small aperture.