Evaluation and Analysis of Sound Absorption across Various Types of Hemp Fibre

Exploring sound absorption solutions, hemp fibre stands out as a compelling replacement for traditional materials like fiberglass, foam, and mineral wool. The aim of this study is to conduct a comprehensive investigation into the sound absorption of six different types of fibre produced from hemp cultivated in the Baltic region. The sound absorption was measured using the impedance tube, transfer function method in accordance with ISO 10534-2 standard. The hemp fibre samples were changed in thickness of 20, 40, 60 mm and density from 50 to 250 kg/m3 in steps of 50 kg/m3. The sound absorption coefficient reaches up to 0.99 at medium and high frequencies. Absorption peaks occur at frequencies of 1000, 1250, 1600, 2500, 3150, 4000, 5000 Hz, depending on the measured fibre thickness, density, and type of measured fibre. It has been determined that in all cases, increasing the thickness of the hemp fibre sample increases sound absorption at lower frequencies. Sound absorption at lower frequencies also generally increases when using denser fibres, but this also depends on the type of hemp fibre being studied. Peaks in the sound absorption coefficient of 0.96-0.99 were mostly achieved when testing fibres with densities of 50, 100, and 150 kg/m3.