Abstract

The widespread adoption of cross-laminated timber (CLT) in building construction faces challenges, especially concerning low-frequency impact noise. Conventional methods for addressing this issue requires thick floor assemblies. This study suggests embedding acoustic black holes (ABH) into CLT floors as an alternative solution.

Functioning as a wave guide, the ABH concentrates energy in specific regions where it is absorbed by the damper. The finite-element method is used to analyze the vibro-acoustic response of CLT plates embedded with a periodic grid of ABH indentations (ABH-CLT). The goal is to evaluate the influence of the outer radius, number of indentations, and structural damping on the vibro-acoustic response within 50-800 Hz and assess reduction in radiated sound power.

The structural response shows that including ABH in CLT floors leads to unintended resonance frequencies. However, characterizing these changes is challenging due to other influential variables. Likewise, varying the number of indentations does not show a clear trend in radiated sound power at a loss factor of 0.03. However, with a higher loss factor (0.2), the trend favors maximizing the indentations.

Increasing the outer radius shifts the structural response to lower frequencies, but the acoustic response remains unpredictable at a loss factor of 0.03, suggesting that the amount of damping is more influential this frequency range.

In the third-octave band, ABH-CLT consistently attenuates sound power levels at higher frequencies above 400 Hz, which is equally achievable by damping a CLT without ABH. However, the ABH is not effective in mitigating impact noise below 400 Hz.