In a study published recently in the Journal of Neuroscience, researchers at McGill University and the Universite de Montreal claim the tone-deaf have a thicker cortex in certain parts of their brain.
"We've actually been able to isolate and specify regions in the brain that appear to be different, structurally speaking," Dr. Krista Hyde, the study's lead investigator and a post-doctoral fellow at the Montreal Neurological Institute, said in an interview Wednesday.
"This study really helps us understand these anatomical differences."
Tone-deafness - also known as congenital amusia - affects about four per cent of the population. It is a lifelong disorder that hinders the ability to listen to or create music.
One person involved in the study even described music as "pots and pans being thrown on a kitchen floor."
"It's a disorder that does affect people very importantly - socially and also very personally as well because music really is universal," said Hyde, who is also a professionally trained pianist.
Hyde's team, which included researchers from Montreal's International Laboratory for Brain, Music and Sound Research, compared the brain images of a tone-deaf group with those of a musically adept group.
Using a range of musical tests, Hyde's team found a correlation between musical performance and the thickness of grey matter. The thicker the cortex in those parts of the brain associated with music, the lower a person's musical aptitude.
"This corroborates our story that these individuals perceive the musical world in a different way," Hyde said, adding that in this respect there are many parallels between tone-deafness and dyslexia - a learning disability that affects reading ability.
The findings from the study - entitled "Cortical Thickness in Congenital Amusia: When Less Is Better Than More" - will allow researchers to build on previous findings that showed tone-deafness to be hereditary.
"We'll really be able to get at tracing the linkage between genes, cognition, behaviour and the brain," Hyde said.
The science behind music has become a fertile ground for research given that several different parts of the brain are involved in the development of musical faculties.
"That's really the interest for us, to really look at music as a tool to understand the human brain," said Hyde.
But she also admits to a more personal desire to see her research contribute to rehabilitation techniques for the tone-deaf.
"Music is such an important part of the human experience," she said. "We hope to... allow (the tone-deaf) to hear music the way others do and get pleasure out of it."
