wooden ear

noun3

1. •
   Tone-deafness of any kind.

   • have a wooden ear
2. •
   Tone-deafness for musical tone.

   • A music teacher is challenged when a student seems to have a wooden ear.
3. •
   Tone-deafness for usage tone.

   • She fancies herself a writer, but she'll steamroll idiom in a way that reveals a wooden ear.