Aural Discomfort Evaluation of Barometric Pressure in High-speed Train

Abstract

Interior pressure of high-speed train varies when it passes through tunnels, which usually caused different levels of aural discomfort. As tympanic membrane (TM) plays a prominent role in pressure energy conversion and transmission, a finite element (FE) model including annular ligament (AL), pars flacidda (PF) and pars tensa (PT), was established in line with its anatomical structure. To quantitatively assess the barometric quality of train cabins, on-board tests were conducted to collect the interior pressure change history. Additionally, TM simulation in LS-DYNA was implemented to investigate the relationship between pressure changes and vibration characteristics. Based on the simulation results, displacement and velocity transfer function (VTF) of umbo were integrated as two indicators to judge aural discomfort and four discomfort levels were divided ranging from ideal, good, bad to worse. The results indicate that the threshold of displacement for each discomfort levels is 1.81μm, 2.10μm, 5.95μm and 11μm _______________________ 363respectively and the lower and upper bounds of VTF were confirmed as well. By imposing the recorded interior pressure onto TM surface, the displacement and VTF were produced. Depending on the established aural discomfort judgment method, the results derived from simulation under interior pressure load reveal that travellers in passenger cabin of head car experience large proportion of inner ear annoyance while crew in driver cabin undergo mixed discomfort from both TM and inner ear.