a Three factors for the description of english vowels a I. The height of the body of the tongue highest point of tongue(vertical axis) a I. The front-back position of the tongue highest point of tongue(horizontal axis) l. the degree of lip rounding-lip posture◼ Three factors for the description of English vowels ◼ I. The height of the body of the tongue – highest point of tongue (vertical axis); ◼ II. The front-back position of the tongue – highest point of tongue (horizontal axis); ◼ III. The degree of lip rounding - lip posture