Sutherland's early recordings show her to be possessed of a crystal-clear voice and excellent diction. However, by the early 1960s her voice lost some of this clarity in the middle register, and she often came under fire for having unclear diction. Some have attributed this to sinus surgery; however, her major sinus surgery was done in 1959, immediately after her breakthrough Lucia at Covent Garden.Joan Sutherland, Russell Braddon, Collins, 1962 In fact, her first commercial recording of the first and final scene of Lucia reveals her voice and diction to be just as clear as prior to the sinus procedure. Her husband Richard Bonynge stated in an interview that her "mushy diction" occurred while striving to achieve perfect legato. According to him, it is because she earlier had a very Germanic "un-legato" way of singing.
