Ah, in this case
Aaron,
Karen and
Barret pronounced AR- rhyme with carrot and barren, and it's the EHR that is supposed to signify a pronunciation like "air" "care" "bare". These should be quite distinct in both length and phonetic value. This is all detailed in BtN's basic guide to pronunciation: A- fat, pat, cat; AH- far, par, car; EH- fair, pear, care. Now in some dialects the A of cat may sound "almost the exact same" as the Eh- of care, but I've never heard one, whereas I do know the distinct pronunciations with a long initial EH "EHR-ən" and the short initial A "Ar-ən".