The impact of external environments on noise inside a train car

Trains travel through various environments typically on tracks above ground or in tunnels. There are three main types of tunnels, which have different cross-sections according to their excavation methods. When trains pass through different environments, the perceived noise inside a train car can change. To consider appropriate acoustic treatment, the effects of the environment on noise inside train cars were investigated in this study. The noise inside a train car traveling through tunnels had a salient sound energy around 250 Hz, and came from the doors and windows of the train car. This suggests the effectiveness of acoustic treatment in the side walls of the car for the low frequency band. More reflections enter the train cars from tunnels with a circular cross-section in tunnels constructed by a boring machine, which drills tunnels before the insertion of lining segments. Acoustic treatment is likely to be needed in tunnels constructed using this method.