We report on automated extraction and analysis of words from a digital dictionary of Hiaki which enabled the discovery of patterns in the distribution of vowels at the ends of words according to their parts of speech–whether the word is a noun, verb, etc. We wrote a computer script that automatically extracted Hiaki words from a Microsoft Word dictionary and sorted them according to part of speech and word-final vowel. We found that the vowel [i] (as in the English word “feet”) is not allowed at the ends of verbs and [e] (similar to “bay” in English) is not allowed at the ends of adjectives. There were a few exceptions, and we investigated each one in detail. We discovered that in the case of supposed “verbs” ending in [i], the dictionary-makers had mostly miscategorized, misspelled, or otherwise mistakenly presented the words — they weren’t verbs. We present a theory that active Voice (“I threw the ball” vs. “the ball was thrown by me” where the 1st example is active and the second is passive) is conveyed by the sound [e], which overwrites the [i] at the end of the basic ‘stem’ forms of verbs to produce free verb forms that end with the sound [e] when spoken aloud.