Abstract: Modular CLT systems are becoming a preferred choice for rapid, green building projects, but they face a persistent challenge with 'vibro-acoustic' performance. Because they are lighter than traditional materials, they often fail to block deep, low-end frequencies or the thud of impact noise traveling between structural pods. This paper presents an investigation into the acoustic performance of timber volume elements (volumetric units) through laboratory testing and/or in-situ, factory-assembled measurements. The study evaluates the impact sound and airborne sound insulation of mass layers. Key findings suggest that while bare CLT modules struggle to meet high-end building regulations (e.g., sound class C), the addition of engineered resilient materials, elastomer intermediate layers, and gypsum board can significantly improve airborne and impact sound insulation. Furthermore, the study analyzes flanking sound transmission through joints and the efficiency of metallic connectors. The study shows that mass timber modules can be just as quiet as traditional buildings if the floors, ceilings, and joints are designed with care.

Keywords: Low-Frequency Airborne Insulation, Prefabricated Mass Timber, Weighted Impact Sound Level, Volumetric Timber Modules, Cross-Laminated Timber (CLT), Flanking Transmission, Sound Transmission Class (STC), Impact Insulation Class (IIC), Resilient Mechanical Decoupling, Acoustic Performance

Pages: 8-18