When ending Y is not part of a vowel team and changes to I before a suffix, the I often keeps the same sound as the Y, as in “muddy” to “muddied” and “dignify” to “dignified”. This is a helpful reading and spelling pattern, but it is not always reflected in speech. In longer words, the suffix, accent, and natural speech can change or reduce the vowel sound, as in “plenty” to “plentiful”.  In speech, the I does not keep the sound of the Y in “plenty”, to “plentiful”, and it changes to a schwa sound.