Comparison of Static Wave Ratio and transfer Function Method in Determining the Sound Absorption Coefficient of Materials

Background and Objective: Sound absorption coefficient determination is an important factor in selecting the proper materials to control indoor noise. Therefore, this study aimed to compare the results of sound absorption coefficient of different materials by standing wave ratio and transfer function method, as well as developing a regression model in adjusting the provided results. Materials and Methods: The current study was conducted on 46 acoustic materials. In order to measure the absorption coefficient of different materials, two instruments called the impedance tube (model 9410, AvaSina, Iran) and the impedance tube (model SW 260, BSWA, USA) in compliance with ISO 10534-2 in the frequency range of 125 to 2000 Hz were utilized. Results: The obtained results from the regression model revealed that frequency of 500 Hz has the highest correlation (r=0.968, R2=0.936), and the lowest correlation coefficient was found at 125 Hz (r=0.368, R2=0.136). In addition, the correlation coefficient of NRC was 0.829. Conclusion: The results showed that the two methods were consistant at the frequencies of 250, 500, 1000 and 2000 Hz. It can be concluded that the standing wave ratio method is a reliable approach in determining sound absorption coefficient of acoustic materials.