LT7182B - Louvered noise barrier with hemp fiber - Google Patents

Abstract

The invention is intended for use in reducing noise generated by equipment that requires high air permeability or cooling to function properly. By using plant-based material - hemp fiber - in the production of the louvered noise barrier, the principles of the European Green Deal are upheld, and clean production is implemented. The noise barrier consists of horizontal metal perforated louvers filled with hemp fiber and mounted in vertical profiles, two of which have adjustable height. By screwing or unscrewing the thread located in the profiles, the tilt angle of the louvers can be adjusted. A portion of the propagating sound waves reflects off the perforated plate, while another portion passes through the perforations into the interior of the louvers, where it is absorbed by the hemp fiber, and later reflected by solid metal sheet. The louvered structure, consisting of 7 horizontal louvers filled with bleached hemp fiber at a density of 200 kg/m³ inside the louvers, achieves a maximum sound insertion loss (IL) of up to 18.13 dB, a maximum sound insulation index (R') of up to 23.0 dB, weighted sound insulation index (R'w) of up to 14.1 dB, and an equivalent sound level reduction (LAeq) of up to 9.9 dB(A), depending on the tilt angle of the louvers. The greatest efficiency of the louvered structure with hemp fiber is observed in the mid and high-frequency ranges, around a frequency of 1600 Hz.