Chin, W. J., K. S. See, Y. H. Ng, J. L. Gan, and S. Y. Lim. “Technologies for Indoor Noise Attenuation: A Short Review”. Progress in Energy and Environment, vol. 9, July 2019, pp. 1-10, https://www.akademiabaru.com/submit/index.php/progee/article/view/1053.