Often when the plural forms of words are added or when there are other inflectional changes, vowels must be reduced or lengthened because of the shift of the stressed syllable (or a change in the location of the accent). I. VOWEL REDUCTIONS • Nouns In nouns the stressed syllable can be changed for the following reasons: a. The addition of the plural, dual, or feminine endings. b. When a word goes into the construct state (i.e., it is joined together with other words).