Influence of variable sound-absorbing devices on room acoustical parameters of reverberation and intelligibility in medium-to-large multipurpose halls.

Multipurpose halls are designed to host various performances. However, achieving the ideal reverberation time (RT) for each of the different performance types can be challenging. This study investigates five halls of various sizes to determine the effects of sound-absorbing devices on variable RTs in multipurpose halls. The composition and sound absorption properties of the finishing materials were investigated in areas where sound-absorbing devices were not applied. Further, the changes in the room acoustic parameters of these medium-sized multipurpose halls were analyzed using computer-based acoustic simulations to find a suitable answer among the various solutions tested. By applying sound-absorbing devices (resonant-type) to 25% of the walls and ceilings of the target halls, the absorption and reflection modes displayed a variability range of more than 0.5 s in the bass-mid frequency (250-500 Hz). However, a variable range of 0.18 s was found in the high frequency (2000 Hz). To improve the low variable range in the high frequency, a partial application of a high-frequency high-performance sound absorption banner (porous-type) was used to secure a variable range of 0.35 s in the high frequency. Variable sound-absorbing devices should be considered to achieve effective RT variation for all frequencies.