Live-action movie soundtracks have rebooted the orchestra pops concert just in time, Emil de Cou believes.

De Cou, who will lead the Chicago Symphony Orchestra in live-to-picture performances of “Harry Potter and the Prisoner of Azkaban”  (2004) on June 27-29, thinks the current boom in live film scores is “just terrific, one of the best things that could have happened,” he said. “The pops format hadn’t changed since the 1950s and Arthur Fiedler, with famous older people of our parents’ generation, and the orchestra in the background.”

A successful movie concert means that de Cou has to be “very, very clear and accurate. There’s two hours of music, and we have two rehearsals. It takes an orchestra like the Chicago Symphony to do this.” For most movies, the score was never designed to be played live straight through, because the original recording happened in a studio over days or weeks. In concert, the workload for the orchestra, he said, is “like the last three Tchaikovsky symphonies in a row,”

Guest conductor Emil de Cou leads members of the Chicago Symphony Orchestra in the 2017 edition of “Merry, Merry Chicago!” | ©Todd Rosenberg Photography 2017

Nevertheless, the format is bringing enthusiastic new audiences into concert halls. “It’s the best way to break down the barriers,” de Cou said. Growing up, he absorbed the attitude that orchestral music was for rich people, “but this is God’s gift to opening the doors of concert halls.” Worrying over whether film audiences will come back to hear Mahler misses the point; many people who come to hear Mahler wouldn’t attend Harry Potter, either. “There’s no reason why we have to keep presenting concerts the way we did in the Eisenhower administration,” he said.

De Cou’s two main niches as a conductor are ballet and live movie scores, and the common factor is “a precise tempo memory,” he said. “Conducting ballet is like a live-action silent movie.”

But he achieves those precise tempos without a using click track: a pre-recorded beat synchronized to the movie that’s piped in through an earpiece. “I’m looking at the screen, and the musicians are looking at me,” he said. “It’s very tricky.” Preparing to conduct a film takes 30 or 40 hours of study, watching the movie with the sound turned off while he follows the score. “It’s pretty tedious, but it’s necessary,” he said. “I get very familiar with Harry and Hermione after awhile.”

Skipping the click track helps keep the music spontaneous, de Cou said, and he will sometimes forgo precision when “I would rather fudge here and there and let musicians make beautiful phrases. That’s the normal fluctuation of people making music.” But, he quickly added, “The explosion [climax] always lines up.”

In the concert hall, audiences expect both a film experience and a music experience, and de Cou vividly remembers how he accidentally got a lesson in the power of music in a film. He was at the Kennedy Center in Washington, D.C., the afternoon before a concert of “E.T.” (1982), and the technicians were running the final bike-chase scene without sound, to test the equipment. De Cou was struck by how boring the film seemed — but that night, “everyone was in tears at the end,” he recalled. “It’s the music that elevates it from something ordinary to something magical and inexplicable.”

Working in the opposite direction, visual or story elements can help make sense of difficult music. De Cou once heard the San Francisco Symphony perform Stravinsky’s 12-tone ballet Agon for a sophisticated subscription audience, “and they hated it. Hardly anyone applauded. But across the street, at the [San Francisco Ballet], it was a hit. The difference is that people listen with their eyes.”

Similarly, de Cou said that composer John Williams uses some avant-garde techniques in “The Prisoner of Azkaban,” such as noting spots where the strings should play 12 notes in a random order, or asking the brass to improvise tone clusters. When music is supporting a dance or a movie, he said, “you can sneak many crazy things in the back door.”

TOP: Emil de Cou takes questions during a reception ahead of a “Merry, Merry Chicago!” concert last season. | ©Todd Rosenberg Photography 2017