I-mutation (also known as umlaut, front mutation, i-umlaut, i/j-mutation or i/j-umlaut) is a type of sound change in which a back vowel is fronted, or a front vowel is raised, if the following syllable contains /i/, /i/ or /j/ (a voiced palatal approximant, sometimes called yod, the sound of English <y> in yes). It is a category of regressive metaphony, or vowel harmony.

I-mutation (also known as umlaut, front mutation, i-umlaut, i/j-mutation or i/j-umlaut) is a type of sound change in which a back vowel is fronted, or a front vowel is raised, if the following syllable contains /i/, /i/ or /j/ (a voiced palatal approximant, sometimes called yod, the sound of English <y> in yes). It is a category of regressive metaphony, or vowel harmony.