Additional context:
Native speakers of my mother tongue do not all understand each other due to some pretty extreme dialects. Now that I’m in Europe, I’ve noticed multiple instances of people sometimes not understand the dialect of someone from a village 10-20 km away…
In contrast, for example most American, British, and Australian people can just… understand each other like that?? I never thought much about it before but it’s pretty incredible
I think it’s the harsh consonant sounds. I’m not a linguist and am sure there’s some term for it, but it seems like we identify words in English more from the distinct “framing” of the consonants and are more flexible about hearing variations in how the vowel sounds in between are pronounced.
For example, it’s the same reason that whispering (which largely takes out tone/pitch of vowel sounds) is super easy in English, but more difficult in some other languages.