For most of U.S. movie history, actors spoke in a kind of neutralized Midwestern dialect tinged by whatever quality the actor as star brought to it, like Gary Cooper’s drawl or Barbara Stanwyck’s resinous precision. Objections to John Wayne lumbering through “The Conqueror” as Genghis Khan, as if the enemy horde were cattle left over from “Red River,” went unvoiced or unheard.Things began to change with the European New Wave onslaught of the ’50s and ’60s, when Fellini’s “La dolce vita” became an international sensation and “The 400 Blows” and “Hiroshima, mon amour” were must-sees in arthouses. Suddenly, we were hearing new accents convey complex but familiar human dilemmas. The multicultural movement of the ’80s then insisted on greater ethnic and cultural integrity. Now, the globalization of the economy and increased entertainment buying power of different cultural groups domestically has meant the internationalization of cinema. Films like “Pan’s Labyrinth” and “Children of Men,” whose appeal might once have been only to pale cineastes in dark sweaters and leotards, have jumped to popcorn multiplexes. Though this evolution does not confer truly international casting for U.S. movies — not everyone can be chosen to play “Superman” — it does have casting directors thinking more broadly in terms of picking more nonwhite actors in parts that are traditionally Anglo-American, even when they don’t have to be (not to mention employing fewer white actors in clearly ethnic parts). “Everything has evolved in the past 15 years since I became a casting director,” says Avy Kaufman (“Syriana,” “American Gangster”). “Everybody’s looking for something a little different.” Adds casting director Joanna Colbert: “I knew things were changing when Rick Montgomery cast Keith David, an African-American, as the stepfather in ‘(There’s) Something About Mary.’ For me, it was an inspiring choice. “If a French girl comes to me to read for an all-American part, I’ll probably say no. But I’ll keep her in mind, especially if she’s beautiful and compelling. I’ll find a way to bring her to a director — if he’s opened his film to everyone. If not, and she still wants to play American, I’d advise her to meet with a dialect coach.” Tabu, who co-stars in the Fox Searchlight pic “The Namesake,” is an award-winning Indian actress who enjoys as much cachet in India as a top American actress would in the U.S. Before the explosive interest in Bollywood over the past couple of years, and despite the global reach of a master like Satyajit Ray, Indian actors hadn’t been thinking of a move to America, she says. “With films like ‘Top Gun’ or ‘Pulp Fiction,’ and the specific way American plots unfold, I didn’t see myself fitting in,” she says. “Everything has changed recently. No one thought America and India would merge. It’s like a marriage now.” Despite plaudits for “Namesake,” Tabu doesn’t see herself auditioning for any specific American role, saying she is “much too settled and established in India.” She adds that she doesn’t think color-blind casting is so advanced that an Indian could play an American hero — her “Nakesake” co-star Irrfan Khan will not be leaping tall buildings in a single bound anytime soon. Of course, this comes at a time when Louisiana has elected the United States’ first Indian-American governor — a reminder of the fitfully widening umbrella of U.S. society. If historical trends are any indication, at some point there may well be no barriers to adding an accent to the most traditional roles.