This 2015 article presents: "a critical survey of the prevalent usage of the Montreal Battery of Evaluation of Amusia (MBEA; Peretz et al., 2003) to assess congenital amusia, a neuro-developmental disorder that has been claimed to be present in 4% of the population (Kalmus and Fry, 1980)." Read the full text here here . One of the conclusions is that online tests for amusia are not as reliable as one would hope. Testing in a laboratory environment is preferable. I have put "find a list of labs that offer amusia tests" on my list of things to be done.