This paper proposes a method for evaluating fuzzy voice commands (FVCs) by internal rehearsal. The robot's experience on previous movements is very useful for understanding fuzzy linguistic information. Therefore, an internal rehearsal system is introduced to acquire the robot's experience on previous movements. Such acquisition enhances the robot's capability to interpret fuzzy linguistic information in FVCs according to the current environmental context. The proposed system is used to evaluate the fuzzy linguistic information related to the primitive movements of a robot manipulator. Those primitive movements are realized by behavior evaluation network (BEN) with the guidance of the internal rehearsal system. Mainly, the system is utilized to understand fuzzy voice motion commands (FVMCs) and fuzzy voice joint commands (FVJCs) for controlling the end-effector movements and the single joint movements of the robot manipulator. The proposed idea is demonstrated with a PA-10 robot manipulator.