The first two sound changes in the shift, with some debate about which one led to the other or came first, are the general raising and lengthening (tensing) of the "short a" (the vowel sound of ), as well as the fronting of (the "ah" vowel of and ), in the direction of . Inland Northern raising was first identified in the 1960s, with coming to be articulated so that the tongue starts from a position that is higher and fronter than it used to be, and then often glides back toward the center of the mouth, thus producing a centering diphthong of the type or or at its most extreme ; e.g. "naturally" as . As for fronting towards , it may, for advanced speakers, even be close to —so that "pot" or "sod" come to be pronounced how a mainstream American speaker would say "pat" or "sad"; e.g. "coupon" as .