Investigation of the Sound Absorption Properties of Open-Cell and Closed-Cell Polyurethane Foam Panels in Medium and High Frequencies

Abstract

Background and purpose: Noise pollution is a major challenge in industrial and urban environments, with adverse effects on human health and productivity. The use of sound-absorbing materials, particularly polyurethane foams, is considered an effective strategy for controlling noise. The present study aimed to experimentally investigate and compare the acoustic performance of open-cell and closed-cell polyurethane foams at medium and high frequencies, and to evaluate the effects of thickness and density on the sound absorption coefficient. Materials and methods: In this experimental study, 15 polyurethane foam samples were examined, including 9 closed-cell samples with densities of 0.0202, 0.0166, and 0.0018 kg/m³, and 6 open-cell samples with densities of 0.0288 and 0.0171 kg/m³. Samples were prepared in three thicknesses (1,2, and 3 cm) and cut into circular shapes with a diameter of 3 cm using laser cutting. The sound absorption coefficient was measured in accordance with ISO 10534-2, using the two-microphone impedance tube method, across a frequency range of 1000 to 6300 Hz. Results: The results showed that increasing thickness across all samples led to an improvement in the sound absorption coefficient. The highest absorption was observed in an open-cell foam with a density of 0.0288 kg/m³ and a thickness of 3 cm, with a mean absorption of 0.84 and a maximum value of 0.99 at 2000 Hz. The lowest average absorption (0.27) was recorded in a closed-cell foam with a density of 0.0017 kg/m³ and a thickness of 1 cm. Conclusion: Open-cell polyurethane foam with a thickness of 3 cm demonstrated the best sound absorption performance, attributed to its porous structure and the formation of two absorption peaks at high frequencies. Thickness was identified as the primary factor influencing sound absorption across all frequencies, while density also played a significant role, particularly at higher frequencies. Therefore, selecting an optimal combination of thickness and density is essential for the effective design of noise reduction systems in various environments. © 2026, Mazandaran University of Medical Sciences. All rights reserved.