Today I discovered the word "scurry" and I immediately found that I couldn't tell it apart with "scary". I looked it up and found that it boils down to differentiating ɝ and ɛ, at least according to these Wiktionary entries:
They seem to sound same to me at this point. How could I learn to tell the difference? One idea that comes to my head is to look for words that only differ by this sound, but I'm not sure how to start looking.