Is a tin-ear one who dislikes music or one who dislikes new popular music? Why?
I know folks who couldn't hear well used to use a tin-ear to help but I don't understand the connection between a tin-ear and a dislike of music or of new popular music.
Solution 1:
To describe someone as having a tin ear is to say that they lack accurate hearing or mental perception of sound and/or music. The sensitivity of someone with a tin ear is generally compared to any average or moderately talented person in music. (A moderate to very talented person might be described as having an ear for music.)
People who don't appreciate music or have poor taste in music are commonly said to have a tin ear. If a person dislikes music or dislikes popular music, they can be said to have tin ear, but that would probably be said in a scoffing way, given that it's a subjective opinion.
A person can be said to have a tin ear for music and that would be the same as having a tin ear. One can also be described as having a tin ear for other things. A tin ear for politics means not sensitive or perceptive in politics.
Solution 2:
I've never heard tin ear used as a term applied to someone who "dislikes new music." I've often heard it used to mean someone is tone deaf, and I just checked several dictionaries that seem to back that. TFD defines it as:
an insensitivity to or inability to distinguish differences in musical sound.
So, having a tin ear doesn't mean someone dislikes music; in fact, quite the opposite may be true:
Can you help me tune my guitar? I've got a tin ear.
That said, the Urban Dictionary defines the term as you say:
an inability to appreciate music
a person who does not appreciate music or has poor taste in music
However, I had trouble finding matching definitions in more reputable dictionaries. Moreover, even the UD definition is controversial: It has 4 thumbs-down votes along side a meager 6 thumbs-ups.
Still, if someone doesn't appreciate my favorite music group, or a favorite music genre, I can see how I might jokingly use the term as a gibe at their music tastes:
You don't like U2? You must have a tin ear!
The Urban Dictionary often mentions more colloquial usages like that one.