Amusia is commonly known as tone-deafness. This is a brain disorder where people can’t tell one note from another. They can’t recognize a tune, either. Many people think they have amusia, but most do not. Only about one in 25 people — or four percent — are truly tone-deaf.
In a sentence
People who are tone-deaf can’t hear a tune, but there is nothing wrong with their ears, and scientists still aren’t sure where the problem lies in the brain.