UPDATE: This just in on June 13, 2013: Marni Nixon has had to cancel her scheduled appearance with the Baltimore Symphony this week due to what a press release from the orchestra describes as "a sudden temporary illness."  Read more on the Artsmash blog.

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When the dynamic 1961 film musical "West Side Story" is screened this week at Meyerhoff Symphony Hall and the Music Center at Strathmore, a bit of electronic manipulation will remove one of the most crucial elements in the movie — the orchestra.

Not to worry. Leonard Bernstein's sizzling score will still be heard complete, only played live by the Baltimore Symphony in sync with a showing of a recently restored print of the film.

"I want the orchestra to still be the star," said Eleonor Sandresky from the Leonard Bernstein Office Inc. in New York. She is associate producer of "'West Side Story' — Film with Live Orchestra," which has been making the rounds of orchestras since 2011, the 50th anniversary of the movie's release.

"When you strip out the orchestra [from the soundtrack] and play it live, it actually makes the film greater than it is by itself," Sandresky said. "The orchestration will be just overwhelming when you hear it. The bigness of it makes the emotional impact greater."

In a way, this business of taking something out of the original movie — for a good sonic cause — seems especially fitting in the case of "West Side Story," given that something was taken out of it for the same reason while still in production.

Natalie Wood was hired to play the teenage Puerto Rican Maria, the Juliet character in this "Romeo and Juliet"-inspired story about a tragic conflict between an Anglo gang, the Jets, and a Puerto Rican one, the Sharks.

When Wood started filming, she assumed that her voice — she recorded all the song tracks — would be heard in movie theaters. The producers had a different idea.

Cue Marni Nixon, the precociously gifted soprano who will visit Baltimore as a guest of the BSO to talk about her experiences with "West Side Story" in a pre-performance event Friday. (Three actors who played members of the Sharks and Jets gangs in the movie will also participate.)

When the film project got underway, Nixon was known to industry insiders for dubbing the voice of Deborah Kerr in the 1956 movie version of "The King and I." But studios preferred that such work be kept secret.

"I think they felt that if the public knew, it would take away the value of a picture," Nixon, 83, said from her New York home. "Now, they go overboard the other way. Good actors who are not equally good singers do their own singing."

Nixon was hired, at $300 a day, to be on standby for dubbing Wood.

"When I got the job, I didn't know how much of the singing I would do," Nixon said. "I thought maybe just Natalie's high notes. I just punched in every day. They would tell me what the lay of the land was for that day."

Several of those days found Nixon in front of the studio orchestra, singing the same music that Wood had just recorded for the soundtrack — "I Feel Pretty," "Tonight," "Somewhere" and other songs from a score propelled by Bernstein's indelible melodies and a young Stephen Sondheim's colorful lyrics.

In the control booth, the difference between Wood and Nixon was readily apparent to studio bigwigs.

"It's strange to think that the producers made some of their decisions knowing that they were casting a musical," Nixon said. "After filming began, I guess they were behind the eight ball."

Throughout the production, Wood continued to film scenes to the sound of her own pre-recorded voice, and she continued to attend sessions with a vocal coach in between.

"The coach would have to sneak a recording of her session to me afterward, so I could get a feeling of how she was phrasing," Nixon said. "It was very sneaky and very tricky."

Some examples of Wood's recordings for the soundtrack survive (everything seems to turn up on YouTube eventually). They reveal an earnest, respectable effort that might have satisfied on a small scale, but probably not on the big screen.