Figure 4: Distribution of average formant frequency for each normal versus polyp (left) and normal versus unilateral VCP (right) subjects for females ((a) and (b)) and males ((c) and (d)). Two discriminatory formants from among F1, F2, and F3 are selected for each plot. Regions for distributions are marked with ellipses. For the case of female vocal fold polyp data, F3 mean was used in plotting the figure although its value is larger than 0.05, because only F1 mean was found to be a significant feature from among three formant means.