The interior noise in train carriages has become an important design parameter for passenger comfort with the proliferation of high-speed rail systems around the world, because passengers spend a few hours on these trains for traveling between cities spanning more than 1000 km apart. However, there are limited reported studies on comparing the carriage noise for different high-speed rail systems. In this study, the carriage noise of three high-speed (top speed between 200 and 300 km/h) and four express rail systems (top speed between 100 and 200 km/h) was recorded with an Android smartphone running Noise Explorer (an app we have developed for measuring noise) and analyzed on PC to benchmark differences among high-speed and express trains. The advantage of using a smartphone for measurements is to leverage citizen scientists for large-scale-simultaneous measurements. The results show that the average carriage noise level is between 64 and 75 dBA which is well below the typical legally acceptable limit of 85 dBA over an 8-h period for noise exposure. The average carriage noise level in dBC was found to be much higher than the corresponding average carriage noise level in dBA, indicating a significant presence of low-frequency content in the carriage noise. Finally, the carriage noise for a train in a tunnel was found to be higher than the same train on an open surface track by 4 to 7 dB.