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."
La Scala a memorable concert conducted by Arturo Toscanini—twice La Scala's principal conductor and an associate of the composers Giuseppe Verdi and Giacomo Puccini—with a soprano solo by Renata Tebaldi, which created a sensation. La Scala hosted the first productions of many famous operas, and had a special relationship with Verdi. For several years, however, Verdi did not allow his work to be played here, as some of his music had been modified (he said "corrupted") by the orchestra. This dispute originated in a disagreement over the production of his "Giovanna d'Arco" in 1845; however the composer later conducted his "Requiem" there