Normal incidence sound absorption coefficient of materials is usually calculated with the use
of an impedance tube following the ISO 10534-2 international standard. The same is applied
in the evaluation of the sound absorption characteristics of pavement mixtures. In this
research an impedance tube which was specifically designed to be used in field conditions
has been developed. In order test the tube six asphalt slabs were constructed in laboratory
and its sound absorption coefficient measured with the new impedance tube. Then, several
road sections, with different types of surface, among dense asphalt layers and thin layers,
namely with rubberized asphalt were tested. In this paper, some considerations are made
regarding the performance of the new impedance tube and the sound absorption coefficient
of each asphalt mixtures.(undefined