Primary Investigation Into Noise Evaluation And Sound Quality In A High-speed Train

Railway noise pollution is becoming increasingly prominent with increasing speed of train. The interior noise of high-speed train affects the ride comfort of drivers and passengers, and restricts the speed to further increase. At present, China Railway has not yet developed the evaluation criterion for the interior noise of high-speed train. So far there is not a unified evaluation system in the world. Aiming at the interior noise evaluation for high-speed trains, the characteristics of interior noise in a high-speed trian are analyzed at its running speed beyond350km/h based on the field measurements. And the present work discusses the shortage of A-weighted sound level in noise evaluation, applicability of interior noise evaluation for high-speed trains using other noise evaluation criteria, and sound quality objective evaluation based on psychoacoustic parameters. The main research work in the present thesis involves:(1) The current study, based on the field measurements, analyzes the interior noise of a high-speed train at its running speed beyond350km/h. The characteristics of the interior noise are identified at different locations of carriages and with the increasing speed. And the noise spectrums at different positions and under different running speeds are analyzed.(2) It discusses whether A-weighted sound level is suitable for the interior noise evaluation for high-speed trains based on the contrast of the normal equal-loudness-level contours, the notable frequency band and the white-noise. Ant it analyzes the applicability of the interior noise evaluation for high-speed trains using other noise evaluation criteria. Afterwards, an aircraft noise evaluation criterion is used to assess the interior noise of the high-speed train after contrast with thier noise spectrum. The results could provide an evidence for constituting new proper noise evaluation criteria for high-speed trains.(3) The present work makes a sound quality objective evaluation of the interior noise for a high-speed train based on psychoacoustic parameters. And it analyzes the relationship between noise frequency distribution and total loudness at different positions and under different speeds. The contribution to the total loudness of the interior noise in different frequency bands is calculated through the method of frequency attenuate. The results could contribute very useful for noise control and comfort improvement of high-speed trains.