I'll rely on experts to tell me whether this notion makes any sense or not.

I think most “tone deaf” people can learn to hear pitches with practice. I have the notion that one must learn to hear. Of course that assumes there is nothing organically wrong in the first place. Some people simply learn to hear—in a musical sense—earlier or more quickly than others. Also, I suspect it's easier to learn when we're younger than later in life.

      - Mark