VOCAL: Elisabeth Schwarzkopf's singing of Swiss folk-songs (Columbia) is wholly delightful. For H.M.V. Fedora Barbieri records very well, but not superlatively, Azucena's arias froin Trovatore and Christoff's Konchak whets our appetite for the Prince Igor that Covent Garden has, inexplicably, not yet given us. Flag- stad's singing of Brahms's Geistliches Wiegenlied is beautiful IAA on the heavy side. For Decca Eugene Conley sings an excellent M'appari from Martha, and Ellabelle Davis's recording from Don Carlos shows a distinct improvement upon her earlier Strauss record.