Acoustic characteristics of deformable origami structures for multi-purpose hall

Abstract

In the multi-purpose hall, variable acoustic elements are required to vary the acoustics of the space tailored to the intended use. The variable acoustics elements are normally achieved by the variable absorption, variable volume and active acoustic system and have been successfully implemented in many halls. However, there is a necessity to explore other innovative variable acoustic elements in order to improve knowledge in this field. In the engineering field, the origami-inspired structures that are made up by folding a flat sheet of material to three-dimensional structures have been an increasing topic of interest among researchers in various applications. The applications range from sandwich structures to mechanical metamaterials and the interest is due to the intriguing characteristics that possessed by the origami-inspired structures. For that reason, this research proposed deformable origami structure as an element that can vary the acoustic condition. To realize the research ideas, comprehensive experimental works were carried out to investigate the feasibility of origami structure as variable acoustic element. Two types of origami patterns namely Triangular and Miura origami fabricated using three different materials (i.e. paperboard, felt and ethylene-vinyl acetate foam material) were investigated in this study. The origami structures were characterized by the absorption coefficient through sound absorption tests in a 1:5 scaled reverberation chamber. The 1:5 scaled reverberation chamber is compiled to ISO 354 (2003) which qualified the chamber to conduct sound absorption measurement. The origami structures were tested in a reverberation chamber by varying the height of the structure to simulate origami deformation using the perimeter-to-area (P/A) ratio method. The result shows that the origami structure has the ability to change the sound absorption characteristic by changing the height of the structure. However, the choice of material used to construct the origami structure has a significant influence on the effectiveness and the frequency range in which the absorption coefficient is altered. The study also shows that the size of the sample plays a critical role in the determination of the absorption coefficient as it introduces the edge effect to the test result. A case study performed in this study also indicated that the utilization of deformable origami structure can vary the acoustics of a space.