Green’s Dictionary of Slang

(W.I.) obstinate, stubborn.

1916		J.G. Cruickshank Black Talk 34: But boy, wha’ make you so ha’d-ears?
1926		E. Walrond Tropic Death (1972) 25: You’re too hard ears.
1931		N. Van Patten ‘Vocab. of the Amer. Negro’ in AS VII:1 28: hard ears. W. adj. Obstinate.
1970		F. Collymore Notes for Gloss. of Barbadian Dial. 59: Hard [...] hard-ears, or heard-eared; disobedient.