Noise generated by railway wagons in operation is produced by large numbers of noise sources. Although the railway transport is considered to be environmental friendly, especially in production of CO2 emissions, noise is one of problems that should be solved to keep the railway transport competitive and sustainable in future. In the EU, there is a strong permanent legislation pressure on interior and exterior noise reduction in railway transport. In the last years in Slovakia, besides modernization of existing passenger wagons fleet as a cheaper option of transport quality improvement, quite a number of coaches have been newly manufactured, too. The new design is usually aimed at increased speed, higher travel comfort, in which reduction of noise levels is expected. However, not always the new designs meet all expectations. Noise generation and propagation is a complex system and should be treated such from the beginning. There are possibilities to simulate the structural natural frequencies to predict vibrations and sound generated by these vibrations. However, the real picture about sound fields can be obtained only by practical measurements. Simulations of the wagon’s natural frequencies and mode shapes and measurements in real operation using a digital acoustic camera Soundcam have been done, which showed that for the calculated speeds the largest share of noise from the chassis was not radiated through the floor of the wagon, as was expected, but through the ceiling of the wagon. To improve the acoustic properties of the wagon at higher speed, it was proposed to use high-volume textile insulation in the ceiling of the wagon. The paper briefly presents modern research approaches in the search for ways to reduce internal noise in selected wagons used in normal operation on the Slovak railways.

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The paper is aimed on types of insulation actually used in washing machines and raising requirements on its characteristics. Next part is design of unconventional insulations, which will be applied directly on appliance. Then, series of tests will pass (according to regulations), so it will be possible to determine acoustic power. After that, we will use simulation to determine impact of insulation rigidity on washing machine shell (with identification of acoustic benefit). Relatively important factor is rigidity of washing machine shell and forces affecting the shell. Force affecting on the shell depends on inner and outer tub weight (and all equipment attached), load, unbalance in a drum and revolutions during spin cycle. Usually more rigid washing machine shell produces less noise than weaker shell. That’s why is relatively important to stiffen shell. Doing this by changing type of insulation is advantageous because it is possible to do without any significant side effects.