Numerical analysis on the improvement of sound insulation performance of plenum doors: effect of sound absorption and...

In recent years, the importance of natural ventilation has been increasingly recognised and achieving a balance between natural ventilation and sound insulation has become a key concern. This study investigates the sound insulation performance of plenum doors - openings designed to achieve both natural ventilation and sound insulation - using the finite element method. In particular, the study examines cases where sound-absorbing materials and micro-perforated panels are inserted into the plenum interior. Previous studies have evaluated the sound insulation performance of plenum doors; however, investigations are limited to specific absorption locations and those involving the introduction of micro-perforated panels have not been conducted. Partial application of sound-absorbing materials and the insertion of micro-perforated panels make it possible to maintain visibility and daylighting. In this way, plenum doors can provide benefits not only in terms of sound insulation but also in visibility and daylight performance. Sound-absorbing materials were applied to the interior surfaces of the plenum, and their effects were especially significant in the mid-to-high-frequency range, with transmission loss increasing by approximately 4-9 dB around 1000 Hz. The degree of improvement was found to increase with the absorption area and coefficient, while differences due to placement location were relatively small, on the order of 0.5-3 dB. The insertion position of the micro-perforated panels was varied and analysed. Micro-perforated panels were shown to enhance sound transmission loss in specific frequency bands. However, securing a sufficient air back space is essential to achieve this effect. Moreover, the effectiveness of micro-perforated panels depends on installation conditions such as surface area and placement, indicating the need for further evaluation.