There are two accent patterns for two syllable words.

1.  Accent on the first syllable:

The accent is usually on the first syllable in three-syllable words.   The unaccented middle syllable has a schwa sound, the short u.  This occurs in the words Jennifer, visitor, happily.

2.  Accent on the second syllable:

When a word has a prefix and a suffix, then the accent is on the root-word.  The root-word will be the second syllable.  This occurs in the words distasteful, biweekly, reflection.

Audio examples of three syllable word stress.