When two vowel letters appear together in a one-syllable word or in an accented syllable, the first vowel often represents its long sound and the second is silent. This holds true most often for ai, oa, ee, ey, ay combinations. The vowel y always follows the vowel or is the only vowel in a syllable and is silent or represents the phonemes we associate with i or e . Although a syllable may have more than one vowel letter, there is only one vowel phoneme in a syllable. The vowel phoneme is the most prominent part of the syllable.
Vowels behave differently in accented and unaccented syllables.
The vowel is most clearly heard in the accented syllable.