Like Sangi consonant mutations, there are two classes of vowel mutation. "Pure mutation" affects the meaning of the word in changing its phonology and "affection" changes only the phonology"Pure Mutation Pure mutation has two subsets; A-mutation and I-mutation. I-mutation involves the raising of the final vowel of the stem, while a-mutation involves the lowering of the final vowel. These diacritics do not have to be used, but are used by the majority of people in order to distinguish the root vowel of a word from its suffixes.Vowel Affection