PBS NewsHour: Searching for the source of phantom sounds

A story on PBS NewsHour about the origins of tinnitus, the phantom ringing that plagues millions of Americans and countless military veterans, and whether stress plays a role in provoking the condition, interviews Richard Salvi, director of the Center for Hearing and Deafness, who says he is not convinced that stress is a root cause for all tinnitus patients, although he agrees there is a correlation of some kind.