New acoustic material for vehicle applications and measurement techniques to determine absorption coefficient for small size test samples 2019-01-1585
A new sound absorbing material for vehicle applications is presented and acoustic properties are investigated in this paper. The material is made of natural leather collagen and inhibits unique characteristics of genuine leather. Production technology uses the residues of leather industry, is ecofriendly and allows fabrication of the parts of any shape. The price is competitive to synthetic polymers.
Absorption coefficient is one of the most commonly used parameters to characterize acoustic properties of materials. There are two main techniques to experimentally determine the absorption coefficient: the impedance tube transfer function method and reverberant room method. In the second case the absorption coefficient is determined at random incident sound field while in the impedance tube only direct incident field is considered. The main advantage of the first method however is the small size of samples. Therefore the impedance tube method was preferred in this investigation, since in the developing process of new material only small samples were available. The standard reverberation room method is limited to minimum size of samples of 10m2. In the paper it was proved that an alternative solution can be the implementation smaller than standardized reverberation chambers in combination of proportionally smaller test samples. This paper also aims the development of methodology for the estimation of optimum sample size for testing in small reverberation rooms, depending on the acoustic properties of the material. A comparison of the absorption coefficients of the new acoustic material determined by using two measurement techniques is presented.
Jüri Lavrentjev, Hans Rämmal, Anna Kozmenkova
Tallinn University of Technology, Mikromasch Eesti Ltd
Noise and Vibration Conference & Exhibition