Acoustic and Psychoacoustic Levels from an Internal Combustion Engine Fueled by Hydrogen vs. Gasoline

Whereas noise generated by road traffic is an important factor in urban pollution, little attention has been paid to this issue in the field of hydrogen-fueled vehicles. The objective of this study is to analyze the influence of the type of fuel (gasoline or hydrogen) on the sound levels produced by a vehicle with an internal combustion engine. A Volkswagen Polo 1.4 vehicle adapted for its bi-fuel hydrogen-gasoline operation has been used. Tests were carried out with the vehicle when stationary to eliminate rolling and aerodynamic noise. Acoustics and psychoacoustics levels were measured both inside and outside the vehicle. A slight increase in the noise level has only been found outside when using hydrogen as fuel, compared to gasoline. The increase is statistically significant, can be quantified between 1.1 and 1.7 dBA and is mainly due to an intensification of the 500 Hz band. Loudness is also higher outside the vehicle (between 2 and 4 sones) when the fuel is hydrogen. Differences in sharpness and roughness values are lower than the just-noticeable difference (JND) values of the parameters. Higher noise levels produced by hydrogen can be attributed to its higher reactivity compared to gasoline.