To filmmaker Pablo Larrain, a juror at the 2013 Venice Film Festival, Jonathan Glazer’s eerie competition picture “Under the Skin” deserved a prize. Composer Ryuichi Sakamoto, also on the jury, was enthralled by Mica Levi’s bold, sui generis score for the film, and he and Larrain spoke passionately of her accomplishment.

What caught Larrain’s eye — and ear — was a symbiotic quality, in which the aural felt inseparable from the visual. The work of Levi, an avant-garde pop artist turned film composer, was simply unlike anything he had experienced.

There’s a growing list of composers who are pushing the boundaries of what film music can be — challenging traditions with experimental works that break the rules of the form.

In Denis Villeneuve’s alien-invasion psychodrama “Arrival,” for example, composer Jóhann Jóhannsson delivers a blend of sonic sensations that add an otherworldly dynamic to the film. The effect is as organic to “Arrival” as the undercurrent of deep-rooted terror was to Jóhannsson’s Oscar-nominated work for Villeneuve’s “Sicario.”

In some parts of the score for “Arrival,” Jóhannsson recorded to a 16-track tape loop for a vaguely analog quality, capturing acoustic sounds from cello, piano, and wind instruments, along with vocals.

“What you’re hearing is very old-fashioned, in a way,” Jóhannsson says. “It’s layers and layers and layers of piano — but without the attack. It’s like piano wire. You’re hearing just the sustain of the piano.”

The work of Jóhannsson and Levi blurs the line between sound design and film music composition, not unlike Steven Price’s Oscar-winning score for “Gravity,” or Trent Reznor and Atticus Ross’ approach to films like “The Social Network” (also an Oscar winner) and “Gone Girl.” Notably, both Price and Ross have backgrounds in audio engineering.

For Patrick Kirst, a composer and adjunct professor for music technology and composition at the University of Southern California, this kind of boundary-pushing is an overarching trend that speaks to the inevitable evolution of the art form.

“The sonic world is the most defining variable that the composer has,” Kirst says, “and the tradition that comes from a pitch-oriented score has been replaced by a sound-oriented world. Sound is not just a carrier of pitch anymore; it has its own character and personality.”

Kirst mentions Ry Cooder’s score for Wim Wenders’ “Paris, Texas” as a notable precursor to this idea of sonically driven film music. He also points to composers such as Eric Serra, Marco Beltrami, and Hans Zimmer — the last of whom is collaborating with hip-hop star Pharrell Williams on a unique approach to Theodore Melfi’s upcoming “Hidden Figures” — as examples of artists looking to “the sonic space a film lives in” as their main gateway to composing for a movie.

“They look for sounds that represent the story, the character, a location,” he says. “It’s not the notes; it’s what you do with them.”

So when Larrain set out to make “Jackie,” a drama centered around Jacqueline Kennedy in the days immediately following the assassination of President John F. Kennedy, he knew where to go for the sound he was looking for. It was the first time he had used original music in one of his films.

“Most of my movies have had pre-existing music that I chose — known pieces, because I’m scared to call someone [for a score] and have them take the thing,” Larrain says. “But this time I wanted to have just one single [musical] perspective.”

Levi’s work on the movie, which Fox Searchlight snapped up at the Toronto festival, is as singular as her “Under the Skin” compositions, an elegant yet unsettling score that once more feels at one with the film. The string instruments give and take, inhale and exhale, with the brave, mourning figure of Jackie trying to hold it together on the screen.

The score wasn’t composed frame-by-frame with the picture. Rather, Levi wrote pieces based on viewing a handful of scenes, and Larrain later cut the film to include Levi’s unusual contribution.

“The sound design — music, atmospheres, almost even just trailer effects — that often occurs in films is much more present in music that people are actually listening to [at home],” Levi says. “The lines between sound and music — at the moment, especially — are indistinguishable, which is really cool.”