The quality of the underlying vowels varies considerably by language; the most common vowel throughout AA is schwa.
ðə kwˈɔlᵻɾi ʌvðɪ ˌʌndɚlˈaɪɪŋ vˈaʊəlz vˈɛɹiz kənsˈɪdɚɹəbli baɪ lˈæŋɡwɪdʒ; ðə mˈoʊst kˈɑːmən vˈaʊəl θɹuːˈaʊt ˌeɪˈeɪ ɪz ʃwˈɑː.