Noise from road racing motorcycles: Emission measurement and immission prediction

Various sound levels characterising the noise emission of Road Racing motorcycles were deternined during the Finnish GP at Imatra in July 1985. The noise was recorded simultaneously in three positions near the racing circuit during all the practice and competition rounds of the classes 125, 250 and 500 cm3. Emission was characterised by the maximum sound level LAmax at 10 m distance, as required by a Swedish prediction model for motor sports noise. Also the equivalent levels LAeg at the same distance were determined. The results were 111 to 113 dB for the LAmax and 97 to 101 dB for the LAeg. The noise immission levels measured at larger distances were compared to those predicted by two alternate models. No direct conclusions could be drawn on the basis of the comparisons, due to the limited number of the immission positions. Finally, the sound level quantity and the data base of the Swedish model were criticized indirect on fundamental grounds. It was concluded that this model is not preferable because of the unsuccessful choice of the noise descriptor LAmax and the obviously unreliable emission data. It was recommended to be replaced by a version using the LAeg as the basic noise descriptor instead.