The "Ghostbusters" score was composed by Elmer Bernstein and performed by the 72-person Hollywood Studio Symphony orchestra at The Village in West Los Angeles, California. It was orchestrated by Bernstein's son Peter and David Spear. Bernstein had previously scored several of Reitman's films and was hired before filming had begun or all the cast had been signed. Reitman wanted a grounded, realistic score and did not want the music to tell the audience when something was funny. Bernstein used the ondes Martenot (effectively a keyboard equivalent of a theremin) to produce the "eerie" effect. Bernstein had to bring a musician from England to play the instrument because there were so few trained ondists. He also used three Yamaha DX7 synthesizers. In a 1985 interview Bernstein described "Ghostbusters" as the most difficult score he had written, finding it challenging to balance the film's varying comedic and serious tones. He created an "antic" theme for the Ghostbusters he described as "cute, without being really way out." He found the latter parts of the film easier to score, aiming to make it sound "awesome and mystical."