Maad Co., as a supplier of acoustic and thermal insulation, has taken part in the study of acoustics of the modernized by ZNTK MM vehicle EZT series EN 57. The electric EN57 series multiple units is the most popular and the most numerous type of electric train on Polish tracks. Overall, in the period 1961 – 1993, Wroclaw “Pafawag” produced about 1,500 vehicles of this type. Currently, the Polish multiple units EZT are being upgraded. The modernization works carried out by ZNTK MM include a spectrum of upgrades of multiple units: from technical improvements to the modification of the passenger space to the change of color scheme. The insulation materials used in the vehicles improve the acoustics and energy efficiency. Thanks to their use, a significant improvement in acoustics was achieved which will add to travel comfort.