Characteristics of hydrogen leakage sound from a fuel-cell vehicle by hearing

Fuel-cell vehicle, run on hydrogen, is known that it has better energy efficiency than existing gasoline cars. The vehicles are designed so that hydrogen leaks from the tank are stopped automatically upon detection of hydrogen leakage or detection of impact in a collision. However, we investigated the characteristics of hydrogen leakage sound from a hydrogen-leaking vehicle and the threshold of discrimination of hydrogen leakage from noise at a crossing with much traffic to examine a method to rescue people safely depending on the sense of hearing in the event of a continuous hydrogen leak. Here, in the discrimination threshold test, we conducted the test by using helium, which is alternative gas of hydrogen leakage sound. We clarified that hydrogen leakage sound from vehicles has directivity, height dependence, and distance dependence. Furthermore, we confirmed the threshold flow rate for distinguishing hydrogen gas when hydrogen leakage is heard at a distance of 5-10 m from the center of the hydrogen leaking vehicle in a 74 dB traffic noise environment.