The number of North Korean refugees entering South Korea is continuously increasing. North Korean speakers show significant differences in vowel and consonant phonetics, length of vowels, and the rhythm and intonation of sentences. The object of this research was to examine the effectiveness of a speech intervention program for North Korean refugees using visual feedback through acoustical analysis for intonation. The subjects were three adults with no speech disabilities who had been in South Korea for less than five years. They had not received any prior treatment for inflection change. The program was set in a discourse situation and used Praat to evaluate intonation and provide visual feedback as demonstrating proper intonation changes through pitch contour. The results after intervention are as follows. First, intonation was significantly improved according to a 5-point subjective evaluation scale. Second, the pitch contour was similar to the contour of standard South Korean pronunciation. The subjects were very satisfied with this initial treatment and showed a high level of motivation. In subsequent study, the development of intervention and the comparison of interventions will be needed as well.