
Lindsey H. answered 06/19/20
ESL Tutor for Speaking, Reading, and Writing
Yes, in many varieties of North American English the "o" in operator is pronounced as /ɑ/. However, there are many different varieties of English, so there are many different ways to pronounce the word. One way is not more correct than the other.
Many rules given for describing English pronunciation have a lot of exceptions. One thing to keep in mind, though, is that stress has an impact. This may account for the difference in how "operator" and "oppose" are pronounced, for example. In "operator," the first syllable is stressed and we have the /ɑ/ vowel in that stressed syllable. However, in "oppose," the first syllable is unstressed. And reduced vowels, specifically the schwa sound, can show up in syllables that are unstressed. So "oppose" is pronounced with /ə/ at the beginning.