When I was in college, I took on a dulcimer student who, when I played her the A string and then the high D string, literally could not tell me which note was higher. She was also totally unable to reproduce either note vocally or on the instrument by ear, even within a half octave.

Thus, I believe she could be called tone deaf.

Yet she loved music, had a good sense of rhythm, and went to great pains to memorize the fingerings it took to play tunes accurately on the dulcimer. She defied her inabilities and, to the extent she could, vanquished them. Very impressive lady.