In English, unstressed vowels usually reduce to a weak "schwa" sound (/ə/), like the a in about or the o in computer . If you stress the wrong syllable, you pronounce the wrong vowels. The Golden Rules of Syllable Stress
For more information on syllable stress and English pronunciation, check out the following resources: The Syllable Stress Survival Guide Pdf
Compound words are formed from two smaller words. Their stress follows predictable patterns: In English, unstressed vowels usually reduce to a