In July 1943, as a result of the American Federation of Musicians boycott of US recording studios, the a cappella vocal group The Song Spinners had a best-seller with "Comin' In On A Wing And A Prayer". In the 1950s several recording groups, notably The Hi-Los and the Four Freshmen, introduced complex jazz harmonies to a cappella performances. The King's Singers are credited with promoting interest in small-group a cappella performances in the 1960s. In 1983 an a cappella group known as The Flying Pickets had a Christmas 'number one' in the UK with a cover of Yazoo's (known in the US as Yaz) "Only You". A cappella music attained renewed prominence from the late 1980s onward, spurred by <answer>the success of Top 40 recordings</answer> by artists such as The Manhattan Transfer, Bobby McFerrin, Huey Lewis and the News, All-4-One, The Nylons, Backstreet Boys and Boyz II Men.[citation needed]
During and after the 80's, what helped a cappella music rise in popularity?
the success of Top 40 recordings