An assessment of the acoustic efficiency of a barrier in the presence of various underlying surfaces was conducted using a two-dimensional model in the COMSOL Multiphysics software package. The peculiarities of evaluating the acoustic efficiency of a semi-infinite barrier and a barrier located on an underlying surface were considered. The analysis of efficiency was performed at sound frequencies ranging from 200 to 1000 Hz with a step of 200 Hz at different heights of the noise source and calculation points. The results of calculations of sound pressure levels at specified sound frequencies for various types of underlying surfaces in the absence and presence of a noise barrier were obtained. The types of underlying surfaces were defined by different values of medium resistance. A comparison of the obtained results was carried out, and the acoustic efficiency of the noise barrier in the considered cases was analyzed.