This paper describes development of a new human-like talking robot WT-4 (Waseda Talker No. 4). WT-4 was developed to overcome the problems related to the lack of variation in the formant frequency of the sounds generated by the previous talking robot WT-3. These problems arose particularly on the first formant (Fl) where frequencies of less than 500 [Hz] could not be reached. And the differences among WT-3's vowels were not clear; which may have been caused by the sound source of the vocal cords and the lips. Therefore, the connection between the vocal cords and the vocal tract was improved, as well as the lips mechanism. As the result of these improvements, WT-4's sounds were quite similar to a human's, and WT-4 was able to reproduce suitable sounds using auditory feedback.