Composer’s quest: Define O.C. in 20 minutes of music. You can help.

Making the rounds in Orange County over the past year, Narong Prangcharoen may have looked more like Ken Burns than Beethoven.

The Pacific Symphony’s composer-in-residence has interviewed people about their cultural heritage and spirituality. He’s taken pictures, recorded video and audio, visited Disneyland and other landmarks. Sometimes, he’s come away with souvenirs — for example, sections of bamboo that Chinese-American residents kept in their backyards.

Once Prangcharoen has gotten a handle on what makes Orange County tick, he’ll have a possibly more daunting task: condensing it all into less than a half hour. The symphony has commissioned him to create an anthem of sorts for the region, and the piece, part of an initiative titled “OC in Unison,” is scheduled to premiere on opening night of the 2015-16 season.

“When I first arrived there, people started telling me the places I should go,” said Prangcharoen, a Thai native and Kansas City resident. “So I went to those places, so I have seen them. And then I learn about them.”

Prangcharoen and the symphony are looking for the public’s help in that learning. Between now and March 31, residents are invited to submit artifacts of any medium that answer two questions: “What makes Orange County home?” and “What unites the people of Orange County?”

The symphony may post some of the submissions on its website and social media pages and display them in the lobby of the Renée and Henry Segerstrom Concert Hall at the Segerstrom Center for the Arts. Entrants will also receive discounted VIP tickets for the work’s premiere Oct. 4.

Given the breadth of possible material — surfing, Angels baseball, freeways, the railroad, Richard Nixon, punk rock — even a local composer might be stumped trying to encapsulate the county, which was founded in 1889, in a single piece of music. Still, the symphony opted to give the task to an outsider, albeit one who is far from a stranger to the Santa Ana-based ensemble.

Prangcharoen won the symphony’s American Composers Competition in 2004 and has collaborated with the group several times since. In 2005, the symphony commissioned and premiered his “Sattha,” an 11-minute work inspired by the Asian tsunami of the year before. His composer-in-residence stint began in November 2013 and will continue through next year.

Carl St.Clair, the symphony’s music director, considers Prangcharoen’s outside perspective on Orange County an advantage — since it gives the composer, in St.Clair’s view, a degree of objectivity that a resident might lack.

“I’m not sure how he’s going to do it,” St.Clair said. “But if anyone can, I know he’ll be able to.”

Already, Prangcharoen has done some musical research around the county. He’s listened to residents rhapsodize about the Beach Boys, who hailed from Hawthorne but namechecked Orange County locations in at least two of their surf-rock classics.

He’s examined Fullerton native Leo Fender’s guitars, which helped shape the formative sound of rock ‘n’ roll, and listened carefully to the bell at Mission San Juan Capistrano. In other cases, Prangcharoen has simply taken in everyday sounds: traffic, trains, waves on the beach.

Whatever form his piece ultimately takes, the composer won’t label it a symphony; he’s reserving that term for a hoped-for later work with an ensemble in his home country. For “OC in Unison,” he prefers the phrase “symphonic poem,” and he cited Ferde Grofé’s “Grand Canyon Suite,” a five-movement work that debuted in 1931, as an inspiration.

“We are looking at 20 to 22 minutes, because a size too big is hard for people to understand at once,” Prangcharoen said. “So I think 20 is a good length for people to just come in and listen to music that they never heard before.”

How to submit

Responses to the questions “What makes Orange County home?” and “What unites the people of Orange County?” may be emailed to OCinUnison@pacificsymphony.org or posted with the hashtag #OCinUnison on Facebook, Twitter and Instagram. Larger pieces can be delivered to the symphony’s office at 3631 S. Harbor Blvd., Suite 100, Santa Ana, CA 92704. Entries may take the form of story, song, dance, photography, art, video or social media.