Use of the Umlaut

German only uses one diacritic, the Umlaut. It appears in printed matter as two dots over the vowel, but in handwriting is best written as two short strokes, not dots. Umlauts are only possible on the vowels a, o, u and the diphthong au, which are all vowel sounds pronounced in the back of the mouth.

For historical reasons, in derived forms of words containing a, o, u or au, the vowel is brought further forward and/or higher in the mouth and this is rel ected in the spelling by umlauting these vowels. This is best illustrated by comparing the singular with the plural of certain nouns, e.g. Bach  Bäche, Loch  Löcher, Buch  Bücher, Bauch  Bäuche (compare ‘goose  geese’). In the examples given, the change in vowel also causes a change in pronunciation of the ch from the hard to the soft variant