Main aim of this thesis is to create an application for measuring threshold in quiet and masking curves in C++ language. First chapter describes basic teory of perceiving sound and phenomenon of masking. Second chapter focuses on description of different hearing measurement methods. Third chapter describes, how the classes and functions for frequency changing oscilator and evaluation were created and how the graph display function works. Next chapter describes, how to use the application properly and how to do the basic calibration, so the data will be displayed correctly. Last chapter shows the correct function, measured thresholds in quiet and masking curves for two subjects.