Periodic resonator-based optimization of an acoustic package made of glass wool

Nowadays, modern urbanization and traffic increase could cause severe noise-induced health damages , such as annoyance, sleep disturbance, or even ischemic heart disease, and thus the interest on environment noise control is quickly growing. Unfortunately, a sound absorbing material that well performs in overall the frequency range is not present in nature. For instance, acoustic solutions such as Helmholtz resonators have good performances at low frequencies, while porous media, whose foam cavities dissipate the energy by viscous and thermal losses, perform better at high frequencies. The scope of this work is to investigate the sound transmission loss of an acoustic package made of glass wool, as well as to propose innovative solutions based on the inclusion of a periodic pattern of Helmholtz resonators inside its core, aiming at passively improving the acoustic performance in a chosen range of frequencies. In order to reach this goal, a numerical model is studied, and the effect of Helmholtz resonators tuned at several frequencies are simulated. For each of these layouts, also the mass increase of the so-called meta-core, compared to that of its classical homogeneous counterpart, is estimated. Results obtained herein may constitute a good basis in order to perform preliminary design considerations that could be interesting for further generalizations.