A singer named Helen Leahey holds the "Guinness World Record" for lowest vocal note sung by a female. It's the musical note D2, and it registered at 72.5 Hertz. She set the record last year, and Guinness decided to share the video again. (The lowest note ever sung by a man is much lower, about eight octaves the lowest note on a piano. But it's so low, human ears can't hear it. )