Lakeith Stanfield, foreground, and Danny Glover in a scene from the film, "Sorry To Bother You." (Peter Prato/AP)

In high school, a friend told En Low that she used a “white girl voice” during a class presentation. The observation took Low, the daughter of Malaysian Chinese immigrants, by surprise — it was the same bubbly voice she used while taking phone orders at her parents’ carryout restaurant in Northern Virginia, and that she would again adopt a few years later while working at a call center for the University of Pennsylvania.

“I had done it since I was really young,” said Low, now 20. “This was just what you were supposed to do.”

Code-switching, or altering the way you speak based on the audience, is a widespread phenomenon among those whose accents and dialects stray from the national standard, long considered in the United States to be the language patterns of the Midwest. A Southerner working as a news anchor in the North might avoid using elongated vowels. A Latina might ditch the Spanglish slang she uses with friends while interacting with white co-workers. After a scolding, an African American child might refrain from speaking in vernacular English at school.

Unconsciously or not, people code-switch to present what they believe (or are told) is a more favorable version of themselves — an instinct often heightened when interactions are conducted over the phone, as is the case in the new movie “Sorry to Bother You.” Boots Riley’s absurdist flick centers on Cassius Green (Lakeith Stanfield), a black telemarketer in Oakland, Calif., who discovers that the secret to professional success is talking to potential customers in his “white voice,” or one dubbed here by an extra-nasal David Cross. It’s like when you’re pulled over by the police, his wise co-worker Langston (Danny Glover) tells him.

The comment is in line with the movie’s biting satire, which raises a larger question about the telecommunications industry: People already hate getting calls from these strangers, whose jobs rely on coming off as trustworthy while still being persuasive. How does one deal with linguistic bias on top of an already difficult juggling act?

“It’s stressful,” said Lariese Reeves, 45, who works in an auto-financing firm’s customer service department. For whatever reason, customers who call sometimes exhibit a great deal of animosity. She referred to her job as an “adult day care” because she must put up with verbal abuse daily — whether the fault is her department’s or not — and soothe angry customers by using an upbeat tone.

Reeves isn’t entirely sure what “upbeat” means in this context but knows it is a word her bosses consistently use in evaluating her performance. Santander, the finance company, uses a speech analytics software called CallMiner that grades employees based on their diction and word choice. Reeves, a longtime Texas resident with a “country accent,” has a tough time with it. She says the right words, but CallMiner can’t always detect them — meanwhile, her bonus has dropped from about $600 each month to just $92.

“It’s very stressful,” Reeves said, “to have your job on the line for an automated system.”

In a sense, CallMiner is a mechanized version of the linguistic profiling that sociolinguist and current Washington University in St. Louis professor John Baugh studied after he experienced discrimination during a housing search in the late 1980s. He found that Bay Area landlords who invited him over the phone to view apartments would often express surprise that he is black when he arrived: “Oh, there must be some mistake,” they would say.

So Baugh conducted an experiment in which he made calls to the same landlords using African American, Mexican American and “standard American” dialects. The results, published in 1999, found a significant difference in the number of appointments granted to the “callers” with minority dialects and confirmed that racism can extend to phone conversations.

This concept also plays a part in another summer movie: director Spike Lee’s upcoming dramedy “Blac­KkKlansman,” set in the early 1970s. Ron Stallworth (John David Washington) is the first black detective to serve in the Colorado Springs Police Department and, determined to prove himself, leads a sting operation against the Ku Klux Klan. He puts the theory behind Baugh’s experiment to an extreme test by “joining” the KKK over the phone, posing as a white man while speaking to local chapter leader Walter Breachway (Ryan Eggold) and even David Duke (Topher Grace) using “King’s English.”

Stallworth can instantly switch between dialects, something many people of color might find familiar. Shereen Marisol Meraji grew up in Sacramento with an Iranian father and Puerto Rican mother, whose family they lived near. Meraji, now 40, would speak English to her parents and Spanish to her grandparents — sometimes within a single conversation — which, coupled with hanging out with mostly Latinos in college, contributed to a Spanglish-infused vocabulary.

Meraji began to work as a production assistant at NPR in the early 2000s, which she recently described as a “huge shock to the system” despite her liberal arts education. Her co-workers used the adjective “uber” regularly. They spoke in references to the Economist and the New Yorker. They were overwhelmingly white.

“I need to be able to speak the language these people are speaking in because my ideas are going nowhere,” Meraji thought at the time. “I learned how to code-switch into NPRese.”

She eventually did, and when she landed 2½  minutes of airtime to talk about hip-hop legend Nate Dogg on “All Things Considered,” she was so excited about the segment that she posted it on Facebook. A friend messaged her privately: “I didn’t want to put this on Facebook, but what’s up with that white voice?”

“It really occurred to me that something was going on inside my subconscious mind,” Meraji said. “It’s this deliberate thing NPR people do. They pronounce everything very deliberately, and it’s slower than I would normally talk.”

Meraji now co-hosts the popular podcast “Code Switch.” Though she works in radio and didn’t deal with the irritated recipients of telemarketing calls, her experience would probably resonate with those who mimic higher-ups or call to mind politicians who adopt the vernacular of their audience.

The University of Pennsylvania is a predominantly white institution, En Low pointed out, so she code-switches from her regular way of speaking — which she has been told by peers sounds “not really educated” and “really slang heavy” — into a softer tone unless surrounded by close friends. It took some effort at the call center, even more so with the pressure applied by a supervisor who would closely monitor calls and criticize employees if they didn’t get people to donate enough money to the Ivy League school. After just three weeks, it got to be too much.

“It was weird to be aggressive in a code-switched voice,” Low said. “So I quit.”

Correction: An earlier version of this article said En Low’s parents were Malaysian immigrants. They are Malaysian Chinese. The story has been updated.