Patrick Mulryan is Corruption’s vocal & dialect coach and I can hardly imagine a richer assignment than the one he has here. Geography is partly the reason. The play is set in London, and while some of the show’s actors grew up in England and a few others in Australia, the majority are from the United States. Adding to Mulryan’s challenges: Most of the actors play multiple roles and many of them portray real-life individuals. How does Mulryan help the actors keep all their voices clear and distinct?

Speaking of the production’s playwright, J.T. Rogers, and its director, Bartlett Sher, Mulryan told me: “J.T. and Bart were not interested in the actors doing perfect impressions of the real-life characters. We’re interested in the intersection between the actors’ skill sets and the human beings being portrayed. And where the actors intersect with the text and the context it sets forth for each scene.”

Mulryan, who grew up in western New York with two English professor parents, gave me an example of this method in Corruption. “Toby Stephens plays the politician Tom Watson,” he said. “Toby grew up in London and he naturally has a contemporary London sound to his voice. But Watson is from the Midlands. So Toby and I worked to give Watson a signature northern sound – ‘up’ became “oop.”’ But that sound, Mulryan continued, may not sound authentic in a private setting.

“Tom Watson is a member of Parliament, and when he speaks there he does some code switching – he alters some of his natural sounds in order to fit in with that environment. And when he is talking at home with his wife, and having an argument with her, other aspects of his voice may come out. So we worked to register all these contexts while making sure what Toby says is intelligible.”

Mulryan, who has an MFA in Acting from the Brown/Trinity Rep program, and now teaches at Juilliard, said that vocal coaches have a hierarchy of priorities. “First, be heard. Next, be understood. And, finally, register the nuances of character.”

Guiding actors to achieve these goals used to be thought of as near-science. “But vocal and dialect coaches have moved on from strict prescriptive teaching,” Mulryan said. “Now we work to identify the sounds that an actor naturally makes that lend themselves to accents and dialects. And we ask: what are the sounds you don’t naturally make and how do we shift your approach in order to make those?”

American actors, commented Mulryan, generally have an easier time creating a contemporary London accent than an accent from more rural parts of the U.K. “London is what they grow up hearing on TV,” Mulryan said. “And younger Americans are not as familiar with R.P.” – meaning Received Pronunciation, the accent regarded in the past as the most prestigious form of spoken English. “I grew up with Masterpiece Theater,” Mulryan said, “where R.P. was prevalent.” For Broadway’s Harry Potter and the Cursed Child, on which Mulryan is voice & dialect associate, he works with a mostly American cast to adjust to MRP (Modern Received Pronunciation).

Given the more complex demands of Corruption, Mulryan said it has been helpful to have two actors who grew up in London as a focal point of comparison for the actors who do multiple accents. “Toby and Saffron” – Saffron Burrows plays the media executive Rebekah Brooks – “each play only one character. They act as a lodestar for the American performers in regards to prosody, or musicality and rhythm.”

As collaborators in the room whose homebase dialect is British, they also provide valuable feedback. “I try to stay open to hearing what anyone in the room has to say,” Mulryan said. “Saffron, for example, pointed out that an accent one of our actors was using for a member of Parliament was too posh. So we adjusted.”

In his work on Corruption Mulryan stresses how helpful it has been to have “an open working environment. Bart and J.T. established a very collaborative rehearsal room which has continued now in previews. To do my job effectively it’s a great help for people to feel they can always speak up. I believe it’s my job not only to make sure the characters’ voices are heard and understood but that the voices of my fellow collaborators are as well.”

Brendan Lemon is a freelance journalist in New York.