Abstract: Fundamental frequency difference limens were measured to study whether pitch perception of mediumrank harmonic complex tones depends on the resolvability of the components and to study the effects of masker tone on discrimination performance. Target tone was presented alone, or mixed with the masker, which were filtered into the same bandpass frequency region (low, medium, or high) to obtain different resolvability. There were five kinds of fundamental frequency difference and four kinds of phase combination between target and masker. Five young subjects participated in experiments, all of whom had normal hearing (thresholds~〈15 dB HL). Results found fundamental frequency difference limens were increased with up-shift frequency region of the harmonics. The fundamental frequency difference between target and masker had a significant impact on the performance, while phase effects were small. Analysis suggested that the resolvability of harmonics had a significant impact on the fundamental frequency difference limens, but pitch perception of medium-rank harmonics was not based on the resolvability. Analysis also suggested that most results of pitch perception of target-masker mixture were closely correlated with peaks on the excitation patterns.