Unaccompanied singing style

• Music style endured in "Pitch Perfect" or "Your Friend's College Concert"
• Unaccompanied, perhaps
• How Pentatonix sings
• Like singing in a shower
• Like some college singing groups
• Like Pentatonix numbers
• Singing without instruments
• Like singing sans instruments
• Without instruments

Wikipedia Word definitions in Wikipedia
Returning to their roots, Johnny Maestro and The Brooklyn Bridge released Acappella , a collection of notable doo wop covers.