But there are many forms of amusia, some of them acquired. Rhythm amusia or rhythm deafness is the inability to detect certain rhythm variations. People with Melody Amusia ( tune deafness or amelodia), "hear a sequence of notes but the sequence makes no musical sense". Melody Amusia is closely related to Pitch Amusia or the inability to distinguish between adjacent tones. "Without these basic elements there can be no sense of a tonal center or key, no sense of scale or melody or harmony".
Dysharmonia, another form of Amusia is the inability to integrate different voices and instruments harmonically. People with Timbre Amusia can not distinguish the quality of sounds produced by different instruments.
I propose the theory that most people born in the last 40 years had acquired some or all of these forms of amusia. I believe, a major factor for this acquired Amusia is the music a person grew up listening to. People ears get accostumed to certain sounds and music, and as a cosequence develop a false perception of what is good music.
Most people in the last 40 years grew up listening to sampling and later computerized rhythms, simplistic melodies, and an almost total lack of harmonization. The quality of popular music (R&B, Rap, Hiphop,reggaeton and even some Rock, Country, etc.) has been decreasing more and more through the years.
The consequences of this, is a whole generation of people with the inability to recognize, pitch, timbre, harmonies, complex rhythms or even the simplest of melodies, the inability to recognized and appreciate good music. If they listen to the beautiful melodies of a sonata, the orchestration of a symphony, the polyrhythms and improvisations of Jazz, they don't like it because their ears are not accostumed to such complexity and richness in music. It is too much for their mind to process.
Someone may ask, why is this important? Well, music, as any other art form should appeal not only to the emotions but also the intellect of people.
Some people saved themselves from developing these forms of amusia through music education. When a person learns how to play an instrument, learns melody, rhythm harmony, that learning experience allow them to get in contact with other forms of music usually not available in the media. This education provides the tools to differentiate between good and not so good music.
In 1990, Isabelle Peretz developed some tests for evaluating amusia, (melody and rhythm amusia). I'm using some of these tests with my students. And it was not a surprise to find out there is a higher failed percentage in people with a music diet of pop music and almost no musical education than with those with a more diverse music taste.