Check out these examples of AMAZING overtones (and undertones) in barbershop performances.
See full performances of the examples here!
The Vagrants: https://youtu.be/CdnTKH6kJDI
Scottsdale Chorus: https://youtu.be/byPx8FHMt0A
After Hours: https://youtu.be/Sk7KeG1WYf8
Main Street: https://youtu.be/pkmkoX5ptGQ