For many years, cuers were instructed that the spoken English vowel /iēeeiēeeiēee/ when unstressed changes to /ɪĭiɪĭiɪĭi/. According to this reasoning, the final syllable of the word happy was cued at the throat: /hhhhhhhhhæăaæăaæăaˈˈˈˈˈˈˈˈˈpppppppppɪĭiɪĭiɪĭi/. Instructors commonly told students that when the word is spoken naturally in a sentence the final syllable was more likely to resemble pit than Pete.
Unstressed Prefixes
This can happen. Unstressed prefixes especially can change /ɪĭiɪĭiɪĭi/ or /əəəəəəəəə/. Consider words like beneath. When the second syllable is stressed, the first syllable is likely to be pronounced as /bbbbbbbbbɪĭiɪĭiɪĭi/.
Dialect