Fourteen fresh, young operatic voices and a dash of improvisation — just the ingredients of a casual and entertaining musical afternoon. The Wolf Trap’s Filene Young Artists Aria Jukebox concert at the Barns on Sunday was a little more improvisatory than expected, however.

As planned, the singers — all from the ranks of the Young Artists summer program — had submitted four possible arias each for the audience to choose from, constructing a program on the spot. But bass-baritone Eric Owens, whose past stint as a Filene Young Artist has led to a major career and who was to anchor the afternoon with arias and some spoofing, got sick, necessitating readjustment. And so it fell to Kim Pensinger Witman, Wolf Trap opera director, accompanist extraordinaire and the afternoon’s emcee, to arrange for some of the gaps to be filled in.

While all the singers shared strengths — big, opera-sized voices, fine diction and good intonation — there was also some notable acting, in bass-baritone Jeongcheol Cha’s intensely engaging Figaro in Mozart’s “Se Vuol Ballare,” mezzo-soprano Renee Rapier’s broad descent into intoxication in Gershwin’s “Vodka,” the firepower patter-song clarity of baritone Tobias Greenhalgh’s “Largo al Factotum” and mezzo Mava Lahyani’s sultry “Mon Coeur s’Ouvre” from Saint-Saens “Samson and Delilah” stood out. There was also some overacting that might have gone over better in a bigger hall, a couple of singers who clearly need to work on the dramatic side of their art and one or two who did not seem comfortable with the stylistic niceties of the arias they were singing.

Reinthaler is a freelance writer.