One goose, two geese, eine gans, zwei gänse is umlaut.
Germanic umlaut is sometimes described as 'a kind of vowel harmony'.
Using David Crystal's example of foot-feet, OE nom-sing *fot nom-pl
*fotiz, the second vowel altered the first, to *fitiz. FooTEES became
Fee-TEEs (via umlaut, and a reduction of the ending), giving a
fossized ModE feet.
Umlaut is dead in English, preserved only in a few fossils like this.
I gather it's weakly alive in German, however, via analogy.
Aggh. I'm told the German-language groups have fights among themselves
on the definition of the word 'umlaut', much for the same reasons
English-speakers muddle the definition of 'umlaut'.
The most commonly understood English definition of umlaut refers to
the double-overdot diacritic: it's an umlaut, whatever the language.
The words trema and diaresis get dragged into the argument.
To tell the truth, I have little insight as to why any language would
deform a vowel to agree with the shape of the next vowel, but this is
exactly what Turkish does. It's as if language incorporates perverted
kind of metathesis as a fundamental phonological feature.
Explain why vowel harmony and umlaut are not related.
Danny Wier says
> The emergence of fronted vowels or Umlaut in Germanic may have been
*influenced* by Uralic and Altaic vowel harmony. However, Umlaut and
vowel harmony are not related.
>
> Umlaut results from the loss of final vowels in Proto-Germanic,
leaving behind a shift in the initial vowel. The rules for Old Norse
(using Danish-Norwegian vowel letters):
>
> 1) a-Umlaut and a-"breaking"
> CeCa > CjaC
> CiCa > CeC
> CuCa > CoC
> 2) i-Umlaut
> CaCi > CeC or CæC
> CoCi > CøC
> CuCi > CyC
> CauCi > CøyC
> 3) u-Umlaut and u-"breaking"
> CaCu > CåC
> CeCu > CøC (Umlaut)
> CeCu > CjoC (breaking)
> (both case in Old Icelandic: CjøC)
> CiCu > CyC
>
> Vowel harmony, on the other hand, affects the non-initial and
suffixal vowels mostly. Uralic languages classify front, back and
neutral vowels. In Finnish, if the stem has a front vowel and the
suffix has a back vowel, the back vowel is fronted: i-a > i-ä, i-o >
i-ö, i-u > i-ü. Turkic has backing of the vowel /i/ with back vowels,
so where e-i remains e-i, a-i becomes a-I (dotless i). There are some
more rules related to rounding of vowels, but I forgot what they are
exactly.
>
> ~DaW~ (it's pronounced Throat Warbler Mangrove)