Of course, being human, we’ve tried to tame its wildness. For a long time, especially in an English academy like Oxford or on the BBC, students and broadcasters were taught a standardized, “proper” form of English called Received Pronunciation that tidied up and rounded off diction like a polished stone. Boris Johnson, David Attenborough and Emma Thompson all speak variations of R.P., which is an idealized accent called a sociolect, not a dialect — its entire purpose is to manage sounds, not the regional idiosyncrasies in vocabulary and grammar that make dialects dialects.

American English has always been more unruly. In 1942, Edith Skinner, a drama professor at Carnegie Mellon who coached Broadway actors on the side, codified what were to her the proper-sounding forms of pronunciation and diction in a book called “Speak With Distinction.” Deploying a series of lessons and drills — practice phrases included “or what ought to be taught her” and “a tutor who tooted the flute” — she taught a form of “Standard American English” that doesn’t exist in a natural form anywhere. (Central Indiana is often cited as being the source of a sort of Everyman broadcasterese, but people there in fact speak with an identifiable Midland American, for instance merging words like “cot” and “caught” to sound the same.)

Skinner’s Standard tries to do away with many of the dialectic peccadilloes that make American speech sound so distinctively American. “It’s the choos and joos, mainly,” Bay explains. “And that linking ‘cha’ sound: didya, cantya, wudya, cudya.” Still, American Stage Speech, also called Good Speech, can be useful, Bay says. If you are asked to play the smartest person in the room, for example, or an angry person trying to hold it together, Skinner’s prescription can help you sound rather tight and clipped and proper.

The world of dialect coaches is small — there are only a few dozen working in Hollywood and New York, and nearly all of them share a single manager (a woman named Diane Kamp, who splits her time between the Catskills and a ranch in Montana). There is no union; nearly everyone is freelance, and a few are associated with a university’s theater department. As a result, they are generalists. At 37, Bay is among the youngest. She has a few repeat high-profile clients (she also worked with Negga on the 2016 film “Loving”), and while she now mostly books steady, longer-term gigs like “Preacher,” her reliable fallback is still charging clients for sessions on a sliding scale. (Dialect coaches charge from as little as $100 to $400 or more an hour.) Actors, or their agents or managers, find her because they either have booked a role that demands a certain sound or aren’t booking anything because they don’t sound a certain way. They are often hoping to achieve that general American sound to break in or refashion their career for the Hollywood market.

Bay grew up in Santa Cruz, Calif. She started out wanting to be an actor and was introduced to speech training in San Francisco, at the American Conservatory Theater. She performed in regional theater and eventually Off Broadway, in a Theater for a New Audience production of “Measure for Measure.” When she was 23, she was accepted into the Shakespeare Lab, a six-week program run by the Public Theater in New York. There, she studied under a dialect coach named Kate Wilson, who helped her realize that as great as acting was, she also loved, and was adept at, helping other actors work on their accents. Before long she had individual actors wanting one-on-one sessions.

After 11 years of coaching, Bay has found a consistent approach. Within the first five minutes of the first session, she is likely to tell you to stand up, put away your notebook and run through a set of physical gestures tied to vowels. “Now, we’re going to be like 5-year-olds,” Bay might say. And: “Remember how acting takes your whole body? So does speech.”