The Effect of Sound Absorbing Materials as Sound Absorber on Train

In everyday life human are exposed to noise that pollutes the environment, such as noise come from radio, machinery, and vehicles on the road. However, humans do not realize that the sound that exists from surrounding environment can sometimes expose a risk to human hearing. Sound that can harm human is a sound that in a very strong condition or as well-known as noise. Noise can be defined as unwanted sound. In addition, noise is often recognized as an unpleasant sound which can be detected by living things. The noise will disrupt people's life. Places that have a high level of noise is like industrial estates, construction sites, roads and quarries. Humans who lives at place that has noise, expose to high risk of hearing loss problems compared to humans who lives in an isolated place. For controlling noise pollution that occurs, the government has enacted laws relating to noise such as the Factories and Machinery Act 1967 states by Commissioner, Law, With, & Nasional, (2006) [1] and the Environmental Quality Act 1974 states by Dosh, (2011) [2], these laws established for the purpose of maintaining and controlling environment so it in a safe condition. Rapid economic growth in this country has also contributed to the noise problem. As an example, increase of train development in major area has causes noise pollution that can gives bad consequences to passengers hearing. Thus, a Abstract: Train is used because it is easy, fast, and inexpensive compared to other public transport. However, the passengers are often disturbed by the noise produced inside the train due to its mechanism. The source of the noise come from underneath of the train where the bogie, gearbox and motor are placed to the train. Thus, the aim of this research is to investigate the effect of sound absorbing materials as sound absorber on train. In this research, three type of sound absorbing materials; soundP materials (acrylic), resonac m-damping and rubber with a thickness 1.5 mm, 3.0 mm and 4.5 mm is installed underneath the train. The train design prototype is drawn by using SolidWorks software, while the sound absorbing materials was analysed by using Finite Element Analysis (FEA) software to get the value of sound pressure level inside the train. All the value collected from the simulation is compared to evaluate the best sound reduction. Even though, resonac m-damping and soundP materials (acrylic) exceeds 65% sound reduction at 50 Hz, but soundP materials (acrylic) is more relevant to be applied because is much lighter than resonac mdamping. Selection of 4.5 mm as the best sound absorbing materials thickness is done depends on the noise level required by Railway Group Standard which is below 84 dB during a working day.