Performance of the loudspeaker in a common living room is analyzed in this project. Moreover, directivity parameters like Directivity Index and polar Directivity Diagram are studied taking as example one specific tweeter construction. Some writers suggest that largely frequency-independent Directivity Index is preferable for loudspeakers in an ordinary indoor stereo setup. To achieve this goal, variation of the original radiation diagram of the studied tweeter is performed including reflectors in the system. A measurement protocol is designed and used. Obtained data is processed by developed software that presents the results.