Investigation of cylinder scatterers coated with moss plants for sound barriers in urban environments

Sonic crystals (SC) have emerged as a promising alternative to conventional concrete sound barriers for mitigating urban noise. The structures attenuate incoming acoustic waves through the formation of band gaps, which result from the periodic arrangement of cylindrical scatterers. The attenuation characteristics are primarily dictated by the diameter of the scatterers and the spacing between them. In this study, we investigate the acoustic performance of SC structures composed of cylindrical scatterers coated with moss plants. Such a configuration is expected not only to enhance noise reduction but also to contribute to urban sustainability by integrating vegetation into the noise control component. Moreover, the SC parameters can be tuned to target specific frequency ranges, making the system adaptable to different urban noise profiles. Our findings indicate that the combination of SC and moss plants leads to improved sound attenuation. It is found that introducing the moss plant on the scatterer surface of the SC can enhance attenuation by as much as 1 dB to 4 dB, depending on the frequency range. Meanwhile, experimental results suggest that attenuation improvements can reach up to 14 dB with similar attenuation behavior. Hence, the proposed structure should be applicable to obtain both acoustic and non-acoustic features in the context of the urban environment toward more sustainable, livable, and resilient cities.