Investigation of source ambiguity of floor noises in a box-frame concrete building from the perspective of junction attenuations: A real case field experiment

This study investigated impact source ambiguity in box-frame multifamily buildings, prevalent in densely populated areas, by examining the transmission of heavy-impact noise and its relationship with junction attenuations across five floors. Contrary to the decline in noise levels with increased distance from the impact source, our findings uncover an intriguing deviation in the behaviour of vibration response levels. Surprisingly, vibrations are often intensified, rather than diminished, with distance. Notably, upon examining each room, instances where non-structural or thin concrete walls exhibited the highest vibration responses were frequently observed. Such instances were particularly prevalent in rooms not directly adjacent to the impact source. This trend markedly impedes residents’ ability to pinpoint the origin location of impact noises. This study reveals an unexpected weakening and reversal of distance attenuation in vibration, linked to the increasing number of valid flanking paths as the junction distance grows. The findings suggest that increasing slab thickness for noise insulation may unintentionally complicate source identification due to diminished junction attenuation in thicker horizontal components compared to vertical ones. To enhance acoustic comfort in such housing, this study recommends minimizing valid flanking paths through improved junction design, addressing an often-overlooked issue of source ambiguity of floor noises.