A golden ear is a term used in professional audio circles to refer to a person who is thought to possess special talents in hearing.
People described as having golden ears are said to be able to discern subtle differences in audio reproduction that most inexperienced and untrained listeners cannot.
Another meaning of the term is used by audiologists to describe aging test subjects who do not demonstrate the expected age-related loss in hearing acuity.
A person said to have golden ears is one who can perceive more subtle changes in sound than others, either by training or by birth.
If the listener and test administrator don't know which sound source is the favored-to-win candidate, the differences often disappear (or the favorite loses).