Alternation between characters which were velar initials and labial initials respectively in Middle Chinese is found in excavated Chu documents of the Warring State Period,which indicates that labialized velar initials became labial initials when followed by back vowels in ancient Chu dialect sometime approximately between the seventh to the fifth centuries BC.

The rounded apical vowels in Huang-Xiao(黄孝)dialects of Jianghuai(江淮)mandarin include two types:the front apical vowel μ and the back apical vowels μ.

The author of this paper made a comparative study of the rounded vowels in six languages of the Mongolian branch and the Mongolian written languages and described the course of the evolution of the Mongolian rounded vowels holding that in the ancient times the two rounded vowels were o and u,while in the middle age, the two vowels had changed into four -- o?u?Ao¨?Au¨.

In some town dialect,the initial "Feng" and the initial "Xia" are pronounced as velar stops.