A barbershop quartet is an ensemble of four people who sing a cappella (just voices) in the exacting barbershop music genre which dates back to the 1900s. These simple songs were often sung in four parts with the melody set in the second-lowest voice.
Origin with the African American community
The first uses of the term, "Barbershop quartet" were associated with African Americans. Henry notes that The Mills Brothers learned to harmonize in their father's barber shop in Piqua, Ohio and this was also common in other neighborhood barber shops in the US. The Mills Brothers moved on to jazz and pop vocal quartet and help start and sponsor other barbershop groups. Their group consisted of John Jr. (1910-1936) basso and guitarist, Herbert (1912-1989) tenor, Harry (1913 -1982) baritone, and Donald (1915-1999) lead tenor.
Edison's talking machine (the phonograph) spread the harmony nationwide. In the early 1900s, pop music success depended on sales of sheet music to the general public. The coming of radio prompted a shift in American popular music. Song writers turned out more sophisticated melodies for the professional singers of radio and phonograph. These songs did not adapt as well to impromptu harmonization, because they placed a greater emphasis on jazz rhythms and melodies that were better suited to dancing than to casual crooning.
Radio quartets kept close harmony singing popular with many amateur singers, though‹and these singers were ready for the revival of barbershop harmony that took place in April, 1938, in Tulsa, Oklahoma.While travelling to Kansas City on business, Tulsa tax attorney O. C. Cash happened to meet fellow Tulsan Rupert Hall in the lobby of the Muehlebach Hotel. The men fell to talking and discovered they shared a mutual love of vocal harmony. Together they set out to stop the decline of that all-American institution, the barbershop quartet, and organized a national barbershop society to keep it going with national singing championships.
Barbershop vocal harmony, as codified during the barbershop revival era (1940s – present), is a style of a cappella, or unaccompanied vocal music characterized by consonant four-part harmony. Each of the four parts has its own role: generally, the lead sings the melody, the tenor harmonizes above the melody, the bass sings the lowest harmonizing notes, and the baritone completes the chord, usually below the lead.
In North America most male barbershop quartet singers belong to the Barbershop Harmony Society (BHS), while most female barbershop quartet singers are in either Sweet Adelines International or Harmony, Inc. Similar organizations have sprung up in many other countries. Notable barbershop quartets: The Haydn Quartet or Edison Quartet (1900s), The Mills Brothers, The Buffalo Bills (1950s, Quartet Champions), The Dapper Dans of Disneyland, The Be Sharps of The Simpsons,The Singing Senators (actual U.S. Senators), Nightlife (1996 International Champs). The Dapper Dans, Barbershop quartet at Disneyworld, Florida consist of Neel (red stripes), JC (light blue), Ken (purple), and Dan (in Yellow)
(Source: Wikipedia, acappellafoundation.org & songbook1.wordpress.com; photo credits: The Mills Brothers, songbook1.wordpress.com; saturdayeveningpost.com; The Dapper Dans, Barbershop quartet, October 2006, Tammy Green, Flickr, Wikipedia)