Noise reduction barriers are commonly used to mitigate noise from engineering equipment. For equipment with air cooling, ventilated enclosures are required; however, solid barriers, such as flat ones, do not always provide the necessary air exchange. In such cases, louver type barriers are employed: a noise protection structure consists of a set of louvers forming a regular pattern. Currently, there are no standard methods for calculating noise reduction by such structures. This study investigates the noise reduction effectiveness of louver type barriers compared to solid barriers of the same height. Finite element method is utilized to model sound wave diffraction from a point source. An evaluation of noise reduction by solid and louver type barriers is obtained, and practical recommendations for the application of louver barriers are provided.