Question: What was the name of the period instrument ensemble that was formed in the 1950s by the conductor with whom Elisabeth Kulman recorded Beethoven's "Missa solemnis"?

full_context: Document 1: Michael Schneider (conductor): Michael Schneider (born 10 August 1953 in Nordhorn) is a German flautist, recorder player, conductor and academic teacher. He is especially connected with later Baroque repertoire such as the works of Telemann and with early Classical repertoire such as the works of Carl Philipp Emanuel Bach, and founded the orchestra La Stagione to perform and record such repertoire.
Document 2: Joseph Haydn: (Franz) Joseph Haydn ( ; ] ; 31 March 173231 May 1809) was an Austrian composer of the Classical period. He was instrumental in the development of chamber music such as the piano trio and his contributions to musical form have earned him the epithets "Father of the Symphony" and "Father of the String Quartet".
Document 3: Carmen Reppel: Carmen Reppel is a German soprano active in both opera and concert. A member of the Staatstheater Hannover , she had a major international career, appearing in leading roles in over 60 operas. She also explored lesser-known repertoire such as Siegfried Wagner's "Schwarzschwanenreich " and appeared in contemporary operas, singing in world premieres of operas by Aribert Reimann and Flavio Testi. She is known for her parts in the "Jahrhundertring ", the centenary production of Wagner's "Der Ring des Nibelungen" at the Bayreuth Festival, including the filmed version of 1980.
Document 4: Elisabeth Kulman: Elisabeth Kulman (born 28 June 1973) is an Austrian classical singer who has performed operatic roles in soprano, mezzo-soprano and contralto repertory. She has appeared at opera houses in Vienna and internationally. She has performed early operas such as Legrenzi's "Il Giustino" as well as new works, creating the role of Gora in the premiere of Reimann's "Medea" at the Vienna State Opera. She recorded Lieder by Mussorgsky, Bach's "Christmas Oratorio" with Peter Schreier and Beethoven's "Missa solemnis" with Nikolaus Harnoncourt. From 2015, she has focused on concert singing.
Document 5: Lotte Lehmann: Charlotte "Lotte" Lehmann (February 27, 1888 – August 26, 1976) was a German soprano who was especially associated with German repertory. She gave memorable performances in the operas of Richard Strauss, Richard Wagner, Ludwig van Beethoven, Puccini, Mozart, and Massenet. The Marschallin in "Der Rosenkavalier", Sieglinde in "Die Walküre" and the title-role in "Fidelio" are considered her greatest roles. During her long career, Lehmann also made more than five hundred recordings. Her performances in the world of Lieder are considered among the best ever recorded.
Document 6: István Kertész (conductor): István Kertész (28 August 192916 April 1973) was an internationally acclaimed Jewish Hungarian orchestral and operatic conductor who, throughout his brief but distinguished career led many of the world's great orchestras, including the Cleveland, Chicago, Philadelphia, New York, Los Angeles, Pittsburgh, Detroit, San Francisco and Minnesota Orchestras in the United States, as well as the London Symphony, Vienna Philharmonic, Berlin Philharmonic, Royal Concertgebouw Orchestra, Israel Philharmonic, and L'Orchestre de la Suisse Romande. His orchestral repertoire numbered over 450 works from all periods, and was matched by a repertoire of some sixty operas ranging from Mozart, Verdi, Puccini and Wagner to the more contemporary Prokofiev, Bartók, Britten, Kodály, Poulenc and Janáček. Kertész was part of a rich musical tradition that produced fellow Hungarian conductors Fritz Reiner, Antal Doráti, János Ferencsik, Eugene Ormandy, George Szell, János Fürst, Ferenc Fricsay, and Sir Georg Solti.
Document 7: Arturo Toscanini: Arturo Toscanini (] ; March 25, 1867 – January 16, 1957) was an Italian conductor. He was one of the most acclaimed musicians of the late 19th and of the 20th century, renowned for his intensity, his perfectionism, his ear for orchestral detail and sonority, and his eidetic memory. He was at various times the music director of La Scala in Milan, the Metropolitan Opera in New York, and the New York Philharmonic. Later in his career he was appointed the first music director of the NBC Symphony Orchestra (1937–54), and this led to his becoming a household name (especially in the United States) through his radio and television broadcasts and many recordings of the operatic and symphonic repertoire. Toscanini had absolute pitch.
Document 8: Rotraud Hansmann: Rotraud Hansmann (born 1 March 1940) is an Austrian soprano in opera and concert. She was a singer in the recordings by Nikolaus Harnoncourt which began historically informed performances, such as Monteverdi's operas and works by Johann Sebastian Bach. She was a teacher at the University of Music and Performing Arts, Vienna.
Document 9: Heike Kumlin: Heike Maria Kumlin is a German soprano. After studying opera in Aachen, she attended the master classes of Edith Mathis, Judith Beckmann, Peter Schreier and Christoph Prégardien. Kumlin has since performed with the Thomanerchor and the Gewandhausorchester, and is renowned for singing works by composers such as Bach, Handel and Mozart. In 2003 she recorded Bach's cantata "O heilges Geist- und Wasserbad", BWV 165 conducted by Gotthold Schwarz, with Alexandra Röseler and Martin Krumbiegel.
Document 10: Elisabeth von Magnus: Elisabeth von Magnus (née Countess Elisabeth Juliana de la Fontaine und d'Harnoncourt-Unverzagt; born 29 May 1954 in Vienna) is an Austrian classical mezzo-soprano. The daughter of conductor Nikolaus Harnoncourt and violinist Alice Harnoncourt, her professional name comes from her first marriage to Ernst-Jürgen von Magnus. She studied recorder in Vienna, theater at the Mozarteum in Salzburg and voice with Hertha Töpper at the Conservatory of Munich. Her other teachers have included Paul Schilhawsky. Early in her career, she performed as a recorder soloist with the Concentus Musicus Wien. She has also worked for ORF as a presenter and announcer.
Document 11: Simone Kermes: Simone Kermes (born 17 May 1970) is a German coloratura soprano, especially known for her virtuoso voice, suited to the opera seria genre of the Baroque and early Classical period.
Document 12: Nikolaus Harnoncourt: Nikolaus Harnoncourt (Johann Nikolaus Graf [Count] de la Fontaine und d’Harnoncourt-Unverzagt; 6 December 1929 – 5 March 2016) was an Austrian conductor, particularly known for his historically informed performances of music from the Classical era and earlier. Starting out as a classical cellist, he founded his own period instrument ensemble, Concentus Musicus Wien, in the 1950s, and became a pioneer of the Early Music movement. Around 1970, Harnoncourt started to conduct opera and concert performances, soon leading renowned international symphony orchestras, and appearing at leading concert halls, operatic venues and festivals. His repertoire then widened to include composers of the 19th and 20th centuries. In 2001 and 2003, he conducted the Vienna New Year's Concert. Harnoncourt was also the author of several books, mostly on subjects of performance history and musical aesthetics.
Document 13: Innsbruck Festival of Early Music: The Innsbruck Festival of Early Music (German: Innsbrucker Festwochen der Alten Musik) is a festival of historically informed performances of music from the late Renaissance, Baroque and early Classical periods which takes place annually in Innsbruck, Austria. It was founded in 1976.
Document 14: Elisabeth Schwarzkopf: Dame Olga Maria Elisabeth Friederike Schwarzkopf, DBE (9 December 19153 August 2006) was a German soprano. She was among the foremost singers of lieder, and was renowned for her performances of Viennese operetta, as well as the operas of Mozart, Wagner and Richard Strauss After retiring from the stage, she was a voice teacher internationally. She is considered one of the greatest sopranos of the 20th Century.
Document 15: Anne Schwanewilms: Anne Schwanewilms (born 1967, in Gelsenkirchen) is a German lyric soprano. She studied gardening before training in Cologne as a singer with the German bass Hans Sotin. She is particularly associated with performing the works of Richard Wagner, Franz Schreker, Alban Berg, and Richard Strauss. She sang the lead role of Carlotta in Franz Schreker's "Die Gezeichneten" at the Salzburg Festival in 2005, recorded and subsequently published on DVD by Opus Arte.
ground_truth: Concentus Musicus Wien