There are lots of papers on polyurethane sound absorption performance. You may found some in the following links:

http://www.sciencedirect.com/science/article/pii/S0266353817306693

http://www.sciencedirect.com/science/article/pii/S0003682X16305308

http://www.sciencedirect.com/science/article/pii/S0020768316302736

http://www.sciencedirect.com/science/article/pii/S1226086X16302787

http://onlinelibrary.wiley.com/doi/10.1002/app.23911/full

http://onlinelibrary.wiley.com/doi/10.1002/app.1982.070270120/full

https://link.springer.com/article/10.1007/bf03218812

If you interested in the theoretical aspect you may take a look in Allard and Atalla’s book, Propagation of Sound in Porous Media (Wiley, 2009)

Thank you so much for your help Iwan Yahya