Opera house electronic libretto systems have begun to be used in some opera houses, including New York's Metropolitan Opera, Milan's La Scala, and the Crosby Theatre of The Santa Fe Opera, which provide two lines of text on individual screens attached to the backs of the seats so as to not interfere with the visual aspects of the performance. A subtle type of sound reinforcement called acoustic enhancement is used in some opera houses. Acoustic enhancement systems help give a more even sound in the hall and prevent "dead spots" in the audience seating area by "...augment[ing] a hall's intrinsic acoustic characteristics."
Cologne Opera former mayor of Cologne. The first opera to be performed there was Carl Maria von Weber's "Oberon". In June of that year the house saw its first world premiere, Wolfgang Fortner's "Die Bluthochzeit". The following month the opera company of La Scala appeared there on tour with Maria Callas in "La sonnambula". The Cologne Opera House occasionally hosts solo recitals and special events; one remarkable such event was concert by jazz pianist Keith Jarrett in 1975 which was recorded and became one of the most popular solo jazz piano recordings of all time, known as The Köln Concert. The house