Abstract: Due to brain’s internal wiring, a beating effect will be created in it as soon as two sine waves with slightly different frequencies be applied to each ear. Brain’s response to such beat remains controversial; therefore and in addition to author’s desire toward investigate the role of beat and carrier frequencies upon the brain, this research introduces a new way for quantifying such phenomenon by using an objective methods of quality assessment. In such method, the criteria of error visibility (differences) between tones had been tested. Delta and Theta waves had been used here to investigate their beat and carrier frequencies inside the brain. Results show a similarity behavior for both Delta and Theta waves. Delta wave appeared to be better effect than Theta due to its highest structural dissimilarity metric (DSSIM) which indicates a greater similarity between tones than Theta wave.