Editing Germanic umlaut (section)

==== I-mutation in High German ====
I-mutation is visible in [[Old High German]] (OHG), c. 800 CE, only on short {{IPA|/a/}}, which was mutated to {{IPA|/e/}} (the so-called "primary umlaut"), although in certain phonological environments the mutation fails to occur. By then, it had already become partly phonologized, since some of the conditioning {{IPA|/i/}} and {{IPA|/j/}} sounds had been deleted or modified. The later history of German, however, shows that {{IPA|/o/}} and {{IPA|/u/}}, as well as long vowels and diphthongs, and the remaining instances of {{IPA|/a/}} that had not been umlauted already, were also affected (the so-called "secondary umlaut"); starting in Middle High German, the remaining conditioning environments disappear and {{IPA|/o/}} and {{IPA|/u/}} appear as {{IPA|/ø/}} and {{IPA|/y/}} in the appropriate environments.

That has led to a controversy over when and how i-mutation appeared on these vowels. Some (for example, Herbert Penzl){{sfnp |Penzl |1949}} have suggested that the vowels must have been modified without being indicated for lack of proper symbols and/or because the difference was still partly allophonic. Others (such as Joseph Voyles){{sfnp |Voyles |1992}} have suggested that the i-mutation of {{IPA|/o/}} and {{IPA|/u/}} was entirely analogical and pointed to the lack of i-mutation of these vowels in certain places where it would be expected, in contrast to the consistent mutation of {{IPA|/a/}}. Perhaps{{Original research inline|date=February 2010}} the answer is somewhere in between &mdash; i-mutation of {{IPA|/o/}} and {{IPA|/u/}} was indeed phonetic, occurring late in OHG, but later spread analogically to the environments where the conditioning had already disappeared by OHG (this is where failure of i-mutation is most likely).{{Citation needed|date=February 2010}} It must also be kept in mind that it is an issue of relative chronology: already early in the history of attested OHG, some umlauting factors are known to have disappeared (such as word-internal {{IPA|/j/}} after geminates and clusters), and depending on the age of OHG umlaut, that could explain some cases where expected umlaut is missing. The whole question should now be reconsidered in the light of [[Fausto Cercignani]]'s suggestion that the Old High German umlaut phenomena produced phonemic changes before the factors that triggered them off changed or disappeared, because the umlaut allophones gradually shifted to such a degree that they became distinctive in the phonological system of the language and contrastive at a lexical level.{{sfnp |Cercignani |2022a}}

However, sporadic place-name attestations demonstrate the presence of the secondary umlaut already for the early 9th century, which makes it likely that all types of umlaut were indeed already present in Old High German, even if they were not indicated in the spelling. Presumably, they arose already in the early 8th century.{{sfnp |Gütter |2011 }} [[Ottar Grønvik]], also in view of spellings of the type {{angbr|ei}}, {{angbr|ui}}, and {{angbr|oi}} in the early attestations, affirms the old [[epenthesis]] theory, which views the origin of the umlaut vowels in the insertion of {{IPA|/j/}} after back vowels, not only in West, but also in North Germanic.{{sfnp |Grønvik |1998}} [[Fausto Cercignani]] prefers the assimilation theory and presents a history of the OHG umlauted vowels up to the present day.{{sfnp |Cercignani |2022b }}

In modern German, umlaut as a marker of the plural of nouns is a regular feature of the language, and although umlaut generally is no longer a productive force in German, new plurals of this type can be created by analogy. Likewise, umlaut marks the comparative of many adjectives and other kinds of inflected and derived forms. Borrowed words have acquired umlaut as in {{lang|de|Chöre}} 'choirs' or {{lang|de|europäisch}} 'European.' Umlaut seems to be totally productive in connection with diminutive suffix {{lang|de|-chen}}, as in {{lang|de|Skandäl-chen}} 'little scandal.' 

Because of the grammatical importance of such pairs, the German [[umlaut (diacritic)|umlaut diacritic]] was developed, making the phenomenon very visible. The result in German is that the vowels written as {{angbr|a}}, {{angbr|o}}, and {{angbr|u}} become {{angbr|ä}}, {{angbr|ö}}, and {{angbr|ü}}, and the diphthong {{angbr|au}} {{IPA|/aʊ/}} becomes {{angbr|äu}} {{IPA|/ɔʏ/}}: {{lang|de|Mann}} {{IPA|de|man|}} "man" vs. {{lang|de|Männer}} {{IPA|de|ˈmɛnɐ|}} "men," {{lang|de|Fuß}} {{IPA|de|fuːs|}} "foot" vs. {{lang|de|Füße}} {{IPA|de|ˈfyːsə|}} "feet," {{lang|de|Maus}} {{IPA|de|maʊs|}} "mouse" vs. {{lang|de|Mäuse}} {{IPA|de|ˈmɔʏzə|}} "mice."

In various dialects, the umlaut became even more important as a morphological marker of the plural after the apocope of final schwa ({{lang|de|-e}}); that rounded front vowels have become unrounded in many dialects does not prevent them from serving as markers of the plural given that they remain distinct from their non-umlauted counterparts (just like in English ''foot'' – ''feet'', ''mouse'' – ''mice''). The example {{lang|de|Gast}} "guest" vs. {{lang|de|Gäst(e)}} "guests" served as the model for analogical pairs like {{lang|de|Tag}} "day" vs. {{lang|de|Täg(e)}} "days" (vs. standard {{lang|de|Tage}}) and {{lang|de|Arm}} "arm" vs. {{lang|de|Ärm(e)}} "arms" (vs. standard {{lang|de|Arme}}). Even plural forms like {{lang|de|Fisch(e)}} "fish," which had never had a front rounded vowel in the first place, were interpreted as such (i.e., as if from Middle High German **{{lang|gmh|füsche}}) and led to singular forms like {{lang|de|Fusch}} {{IPA|de|fʊʃ|}}, which are attested in some dialects.