Brewer's: Boeotian Ears
Ears unable to appreciate music or rhetoric.
“Well, friend, I assure thee thou hast not got Boeotian ears [because you can appreciate the beauties of my sermons].”- Le Saye: Gill Blas, vii. 3.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894