On Vowel fronting in German
Throughout the history of phonology, there have been numerous attempts to explain the phenomenon of vowel fronting in German. Even OT is left with a number of problems when tackling German vowel fronting - because the process seems to originate from around the interface of phonology and morphology; because the phenomenon only seems to behave in more or less generalizable patterns; and because there is a lot of inter-speaker and intra-speaker variation. This paper will start out by describing umlauting and umlaut-triggering conditions in some detail. The description will be followed by a brief overview of the most dominant ideas that had been brought forward in pre-OT literature, and the paper will close with a suggestion of a possible constraint-ranking responsible for umlauting, not forgetting the problems that remain even in an OT-based account.
II. German vowel fronting – the phenomenon
The patterns for which vowels can be fronted in German and which vowels they turn into as a consequence is straight-forward in German: the vowels that can be fronted are the six [back] monophthongs of German, three of them tense, three of them lax, and one back diphthong. In umlaut-triggering conditions, they all turn into their [front] counterpart. An irregularity can be observed in the fronting of /a/ and /a:/, because the vowels they turn into, /ɛ/ and /ɛ:/, are not the exact front counterparts, they are higher. This is usually explained by an underspecification of /a/ and /a:/ for [low]. The German vowel inventory also does not feature an /æ/. A second irregularity can be observed in the fronting of /aʊ/ which changes both vocalic parts to /ɔy/. Wiese assumes a case of Rounding Assimilation for the first part of the diphthong, the change from /ʊ/ to /y/ is completely regular. German spelling places a diacritic of two dots above the umlauted vowel.
 Henceforth ‘German vowel fronting’ will be equal to ‘umlauting’ or ‘Umlaut’ for the sake of brevity