metaphony in Germanic languages, occurring around 450–500, in which vowels are raised or fronted when the following syllable contains /i(ː)/ or /j/; e.g. Engl. foot → feet
The umlauts are a group of sounds in German. They are written ä, ö, ü (or ae, oe, ue).
When a word that has umlaut letters with dots is changed into English, the letters are usually written as ae, oe, or ue instead of ä, ö, or ü.