As a specific instance of this, in prehistoric Old English, a certain class of nouns was marked by an /i/ suffix in the (nominative) plural, but had no suffix in the (nominative) singular. A word like /muːs/ "mouse", for example, had a plural /muːsi/ "mice". After umlaut, the plural became pronounced [myːsi], where the long back vowel /uː/ was fronted, producing a new subphonemic front-rounded vowel [yː], which serves as a secondary indicator of plurality. Subsequent loss of final /i/, however, made /yː/ a phoneme and the primary indicator of plurality, leading to a distinction between /muːs/ "mouse" and /myːs/ "mice". In this case, the lost sound /i/ left a trace in the presence of /yː/; or equivalently, the distinction between singular and plural, formerly expressed through a suffix /i/, has been re-expressed using a different feature, namely the front-back distinction of the main vowel. This distinction survives in the modern forms "mouse" /maʊs/ and "mice" /maɪs/, although the specifics have been modified by the Great Vowel Shift.
Bookmarks