Psychoacoustic analysis of motorcycle noise

Austria offers ideal conditions for motorcycling due to its topography. Residents, especially those living close to the highly frequented routes, are affected by a high amount of daily stress, because of the increasing noise caused by motorcycles. The noise of motorcycles is different to the noise caused by the standard car and features distinctive noise characteristics. Popular motorcycle routes are often situated in rural mountainous areas, where the basic noise level is usually rather low. This contrast of the distinctive noise characteristics of motorcycles and the low basic noise level leads to an increased level of annoyance, compared to standard cars. Due to the changing gradients and directions of the road, road users have to brake and accelerate many times, which also increases the noise level as a result of the engine noise. Moreover, an aggressive style of driving and sometimes the illegal removal of sound absorbers are increasing the noise level as well. The EU guideline 97/24/EG, which regulates motorcycle type approval in the European Union, requires measurements under laboratory conditions and consideration of the A-weighted sound pressure level. In order to represent the subjective perception of the human being of traffic noise better, especially in the case of motorcycle noise, further acoustic and psychoacoustic studies are necessary. In this paper, the connection between physical quantities of car and motorcycle sound events and the human perception of motorcycle noise are analyzed and evaluated. The popular motorcycle route B69 in Styria was chosen as location for the acoustic and psychoacoustic measurements with binaural dummy heads, which were subsequently statistically analyzed. The EU guideline 97/24/EG served as basis for the measurements and was adapted to free field conditions.