Composer Michael Mortilla is planning an 8 1/2-hour public improv session for LACMA’s silent movies

One film tells the story of a young woman whose freewheeling sexual ways meet a tragic end. Another tells the sad tale of a poor man who takes the blame for his girlfriend’s crime. There’s also a realistic observation of daily life in Berlin during the roaring ‘20s.

Since October, these historic silent films — “Pandora’s Box,” “Slums of Berlin,” “People on Sunday,” as well as the documentary overview of the great German city, “Berlin: Symphony of a Great City” — have been screening in the galleries at the Los Angeles County Museum of Art as part of the exhibition “New Objectivity: Modern German Art in the Weimar Republic, 1919-1933.”

Now they are set to get a little musical accompaniment.

Michael Mortilla is a composer and musician who for two decades has improvised scores to all manner of silent films for the Academy of Motion Picture Arts and Sciences, among other organizations. (He has also worked with a pair of legendary choreographers: Alvin Ailey and Martha Graham.)

On Sunday, in a marathon 8 1/2 hour session, he will take his place at the LACMA galleries and play improvised compositions that will help bring these important German films to life — some of which went on to influence filmmakers around the world. (“People on Sunday,” for example, is based on a screenplay written by eventual Oscar winner Billy Wilder.)

“It’s like an audio description,” says Mortilla of the process, “like a translation of what’s going on on the screen.”

Silent pictures didn’t come with scores attached — which leaves the composer plenty of room for interpretation.

“That’s where it can get really revealing,” he says. “Something I see as tender or passionate, others might see as cruel.”

Moreover, creating these scores is more than just creating light sonic accompaniment for a moving picture. “It’s not just about conveying the superficial actions of the characters,” he adds. “It’s the stuff you can’t get in the dialogue.”

The films also offer Mortilla an opportunity to concoct sounds inspired by the era: the early decades of the 20th century, when composers were rethinking the nature of music.

“You have Aaron Copland, Alban Berg, Arnold Schoenberg,” says Mortilla. “There’s a dryness. They distill music down to its essentials — music you wouldn’t have gotten from the romantic period of Beethoven. In the early 20th century, they really distilled music down to an almost psychological component and that’s what I love about these German Expressionist films. They really explore the psyche, the psychology of the characters.”

Mortilla has improvised scores for three of the four films on view in the past, so he’s comfortable with the nature of the material. The real challenge will be the arduous length of the performance: more than eight hours. Even so, he thinks that the long hours at the keys might offer a unique opportunity to work out something interesting compositionally.

“I did ‘Metropolis’ for LACMA in November,” he says. “It’s a long film and while I was working on it, I started finding new things in the music. By the end, I was surprising myself with what was coming out of my fingers.”

Michael Mortilla performs the films of “New Objectivity” on Sunday at LACMA from 10:30 a.m. to 7 p.m. “New Objectivity: Modern German Art in the Weimar Republic, 1919-1933,” is on view through Monday. 5905 Wilshire Blvd., Mid-Wilshire, Los Angeles, lacma.org.

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