Psychoacoustic properties of tire-road noise and the relation to noise annoyance

Rolling noise as the interaction between tire and road contributes strongly to the total road noise in particular as engines become quieter due to more strict noise regulations and the emergence of electric motors. Thus, road traffic noise can be effectively reduced by optimizing vehicle tires and the pavement. Over the last decades, different pavements were developed to reduce tire/road noise as for example a porous asphalt surface or stone mastic asphalt reduce significantly rolling noise over a period of about 10 years. In the past the noise reduction due to different pavement types and layers were validly determined, several measurement methods established and level reduction values incorporated in noise directives like the German guidelines for noise protection at roads. However, little attention was paid to assess the annoyance reduction effect of different pavements in detail. As the road tire noise is not only reduced in level but is also affected in spectrum, road traffic noise annoyance might not be accurately predicted by considering the level reduction only. In the following paper diverse road traffic noise measurements related to different pavements are analyzed from a psychoacoustic point of view and the resulting noise annoyance investigated.