Why do I experience a scratching sound and sensation in my ear when I hear out of tune notes?

Your "Problem" is a damaged Mallus. However if it only does this on out of tune notes it is a gift and you should stick with me kid, we'll go places. so far there is not much they can do for it. An earplug would be the only thing to help the pain. When doctors find out how to fix a damaged Mallus let me know.