Singer 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.
In case you're wondering, Tim Storms sang the lowest note ever sung, about eight octaves below the lowest note on a piano. That's so low, human ears can't even hear it!