A comparison of the Northern Cities Shift and the Southern Shift in vowel pronunciation by American English speakers

Vowels can primarily be differentiated and classified according to the position of the tongue during the production of a particular vowel. Furthermore, the respective position of the tongue in the mouth can be represented in a four-sided diagram. Within this vowel chart, each vowel has its own position, or “phonetic space”, determined by the position of the tongue (Roach 2000: 14-15). The concept of phonetic space is of great importance in the context of chain shifting, because the shift of one vowel from one position to another usually sets off a change in the phonetic space of a neighboring vowel (Wolfram & Schilling-Estes 2006: 75).

As regards the general patterns of chain shifting, Labov (1994: 118-119) distinguishes between “minimal chain shifts” and “extended chain shifts”. Minimal chain shifts only consist of a change in the position of two phonemes: the first, or the “leaving element”, changes its position, thereby leaving behind an empty space. Consequently, a neighboring member, the “entering element”, also changes its phonetic position in order to fill this hole. If several minimal chain shifts are combined systematically and appear in a coordinated sequence, as if the vowels were rotating clockwise in the mouth, one speaks of an extended chain shift. If all of them move far enough, they may be heard as realizations of another phoneme by listeners from another dialect area. This phenomenon of “naturally occurring misunderstandings” Labov 1994: 197) will be exemplified in connection with the description of the Northern Cities Shift in sub-section 3.1. and the Southern Shift in sub-section 4.1.

The main function of chain shifting is to maintain the distance of the affected vowels, which is the decisive factor for the preservation of their phonemic contrast. When a vowel changes its position, it is pronounced in a new way. Thereby it may become similar to the phonetic realization of another vowel phoneme, which, in turn, also moves away from its original position and takes on a new pronunciation. As a consequence, the two vowels do not only remain distinct phones, but also distinct phonemes so that semantic differences can still be conveyed (Wolfram & Schilling-Estes 2006: 76).