Distinguished SOTW member, musician, technician &
Maybe it is worth mentioning that how in tune something is is in comparison to people's ability to hear when something is out of tune. According to research the area that is easiest for people to hear out of tune is around concert G above the staff. Most people can hear about 5 cents difference there, when two notes were played one after the other. Higher and lower notes will be harder to hear, for example around 10 cents diufference possible to hear around the middle C area.