Investigation of the performance of pistachio husks as a sustainable sound-absorbing material

There are ongoing efforts to use eco-friendly sound-absorbing materials to reduce noise pollution. Various sustainable sound-absorbing materials, including agricultural by-products, have been examined in previous research. This study focuses on using pistachio husks as a sustainable sound-absorbing material. To assess the performance, the sound absorption coefficient was determined by filling impedance tubes with pistachio husks to heights of 40, 60, 80, and 100 mm. The sound absorption peak was observed at 0.523 at 1,296 Hz at a fill height of 40 mm, and 0.736 at 532 Hz at a fill height of 100 mm. As the amount of pistachio husks in the impedance tube increased, the sound absorption performance at low frequencies improved. The noise reduction coefficients (NRCs) were 0.456 at 80 mm and 0.428 at 100 mm. This corresponds to a KS F 3503 grade of 0.5M, which shows that pistachio husks have sound absorption properties. However, the sound absorption performance of pistachio husks was inferior to that of other natural materials. Therefore, future research is required to improve the porosity of pistachio husks through various physical and chemical treatments.