A new study can help people or maybe even companies be able to more accurately tell a healthy voice from a sick one. This comes from researchers the National Institute of Technology in Surat in India. They've been looking at this for a while and the theory is that if you think of a tuning fork for example Something that can produce a completely pure note. Well, the human voice is not like that. It's very difficult If not impossible for even a fully trained professional singer to produce a pure note every frequency of sound that we produce comes with a family of higher frequency notes which are related in a system called harmonics. Each of these higher notes what are called overtones are usually quieter because