They're homophones = sound-alikes. Homonyms (name-alikes) are spelled alike but mean different things, i.e. when they're jarring it's because only one of the meanings is appropriate in context, and you guessed wrong.

I grew up exposed to a many-vowels dialect, but I suspect that the reason I use that dialect now (my grandmother's moreso than my parents') is because the fine distinctions between vowels reduce the frequency of homophony. "Affect" and "effect" sound nothing alike! "Erin" and "Aaron" are two completely different names!