High German consonant shift

In historical linguistics, the High German consonant shift or second Germanic consonant shift is a phonological development (sound change) that took place in the southern parts of the West Germanic dialect continuum. The shift is used to distinguish High German from other continental West Germanic languages, namely Low Franconian (including standard Dutch) and Low German, which experienced no shift. The shift resulted in the affrication or spirantization of the West Germanic voiceless stop consonants /t/, /p/, and /k/, depending on position in a word. A related change, the devoicing of the voiced stopped consonants /d/, /b/ and /g/, was less widespread, with only the devoicing of /d/ being found in most dialects.

There is no consensus on when the High German consonant shift occurred; it probably began between the 3rd and 5th centuries and was complete before the earliest written records in Old High German, the earliest recorded stage of High German, were produced in the 8th century. There is also no consensus on where or how the shift proceeded.

The degree of shift varies within High German. Dialects that experienced the most shift are referred to as Upper German, whereas those that only experienced some are referred to as Central German. Different dialects within Upper and Central German also received different levels of shift, with West Central German exhibiting what is known as the Rhenish fan, a gradual reduction of which consonants are shifted, as one moves north.