Evaluation of noise emission from passenger cars in urban traffic; a comparison between electric passenger cars and passenger cars with internal combustion engines

Abstract

Electric vehicles (EV) are becoming a larger part of the traffic flow present in the traffic today. The noise emission from cars driving at higher speed is dominated by the noise of the tyres and the contact with the road. The noise from the engine becomes more dominating at the lower speeds, thus one can start to think how this could make the emitted noise deviate between electric cars and cars with traditional combustion engines. If EVs in the future would contribute to a larger part of the total traffic flow, which is not unlikely, one could question if the traffic noise within densely populated areas would decrease for the roads with lower speed limits. The aim of the project is to investigate if there is a difference between the traffic noise emitted by electric cars compared to internal combustion engine vehicles (ICEV) and if so to what extend. To investigate this, measurements of single vehicles were made at roads with speed limits between 15 km/h and 60 km/h. The sound exposure level (SEL), maximum sound pressure level (SPL), equivalent SPL, sound power level and psychoacoustic annoyance (PA) were analyzed together with a listening test where participants rated the annoyance for both vehicle types for the different speed limits. The results showed that EVs were only a few decibel lower regarding the SEL and maximum SPL and the sound power levels were almost equal. The small deviations could be seen to fall within the uncertainty based upon the calculated confidence interval (CI). From the listening test it was seen that participants rated the annoyance from the different vehicle types equally and EVs were not perceived as less annoying. It could therefor not be concluded fully from the measurement and listening test that EVs were quieter than ICEVs.