"In the literature, perfect pitch is talked about as a fixed ability, so it was quite surprising to find..."

"... that as little as 45 minutes of de-tuned music could temporarily shift note categories.... What this points to is the malleability of the human brain. Relatively brief exposure to flattened music is able to rearrange what was thought to be a very long-term and stable note category. This is a great example of how our immediate surroundings and perceptions can change the way in which we view the world."

What are the other things in the category that that is an example of?