Adding the H to some of these letters wouldn't give the right sound for native english speakers. I would transcribe these vowels using american english like so:
A = ah : rhymes with ma
E = ay : rhymes with hey
I = ee : rhymes with tree
O = oh : rhymes with blow
U = oo : rhymes with shoe
Perhaps it's just dialectal differences. I live in colombia and what I hear daily is an e sound that rhymes with hey, hay, or may.