@ARTICLE{Pleban_Dariusz_Method_2013, author={Pleban, Dariusz}, volume={vol. 38}, number={No 2}, journal={Archives of Acoustics}, pages={191-195}, howpublished={online}, year={2013}, publisher={Polish Academy of Sciences, Institute of Fundamental Technological Research, Committee on Acoustics}, abstract={Efficient ultrasonic noise reduction by using enclosures requires the knowledge of absorbing properties of materials in the frequency range above 4 kHz. However, standardized methods enable determination of absorption coefficients of materials in the frequency range up to 4 kHz. For this reason, it is proposed to carry out measurements of the sound absorption properties of materials in the free field by means of a tone-burst technique in the frequency range from 4 kHz to 40 kHz at angles of incidence varying from 0° to 60°. The absorption coefficient of a material is calculated from the reflection coefficient obtained by reflecting a tone-burst from both a perfectly reflecting panel and a combination of this panel and the sample of the tested material. The tests results show that mineral wool and polyurethane open-cell foam possess very good absorbing properties in this frequency range.}, type={Artykuły / Articles}, title={Method of Testing of Sound Absorption Properties of Materials Intended for Ultrasonic Noise Protection}, URL={http://www.journals.pan.pl/Content/101517/PDF/06-paper.pdf}, doi={10.2478/aoa-2013-0022}, keywords={ultrasonic noise, sound absorption coefficient, tone burst technique, sound absorbing material}, }