Soundtrack
Henry Mancini was originally hired as the film's composer. His opening theme was written in Bachian organ andante, opening in D minor, for organ and an orchestra of strings and brass, intended to express the formality of the grey London landmarks, but Hitchcock thought it sounded too much like Bernard Herrman's scores.
According to Mancini, "Hitchcock came to the recording session, listened awhile and said 'Look, if I want Herrmann, I'd ask for Herrmann'. After an enigmatic behind-the-scenes melodrama, the composer was fired. He never understood the experience, insisting that his score sounded nothing like Herrman. In those days, Mancini had full music measurements sheet and he had to pay all transportation and accommodations himself. In his autobiography Mancini reports that the discussions between himself and Hitchcock seemed clear, he thought he understood what was wanted, but he was replaced and flew back home to Hollywood. The irony was that Mancini was now being second-guessed for being too dark and symphonic after having been criticized for being too light before. Mancini's experience with Frenzy was a painful topic for the composer for years to come."
Hitchcock then hired composer Ron Goodwin to write the score after being impressed with some of his earlier work. Goodwin's music had a lighter tone in the opening scenes, and scenes featuring London scenery, while there were darker undertones in certain other scenes.
Read more about this topic: Frenzy