Singing without instruments

• Like some college singing groups
• Unaccompanied singing style
• Music style endured in "Pitch Perfect" or "Your Friend's College Concert"
• Without instruments
• Like Pentatonix numbers
• Type of singing featured in "Pitch Perfect": 2 wds
• Like singing sans instruments
• Like Pentatonix performances

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