It’s all about the nose. That is the secret to singing classic country music, or at least getting to the heart of the style of singing brought back to life in “George & Tammy,” according to the actors who inhabit the title roles, Michael Shannon and Jessica Chastain.

Variety caught up with the actors as they made the rounds recently to discuss playing George Jones and Tammy Wynette in the six-episode limited series, which premieres Sunday night on both Showtime and Paramount+. (It’ll be a Showtime exclusive for the following episodes.) They discussed how they worked with vocal coaches and music producers to arrive at the literal voices of Jones and Wynette, and also considering the psychology that made George and Tammy’s lives into such an immutable, lifetime duet, whether or not the two were technically together.

The formidable leading man and lady are less about strict impersonations than getting to the soul of why Wynette and Jones made for one of music’s great on-again, off-again couples — Shannon well-capturing Jones’ essential impishness as well as volatility and (in the right moments) good-heartedness, and Chastain more than ably equipped to convey the ambition, sweetness and quietly fierce strength of a country wife who gave as good as she got. “George & Tammy” premieres at 9 ET/PT on the two networks.

To the extent that you worked with a vocal coach on this, or with T Bone Burnett, was there anything transformative that they said or did that helped you find a way into how you were going to sing these roles?

Chastain: I came onto this job in 2010 or 2011. And I sat with T Bone maybe six years ago and sang “Stand by Your Man” and said, “I just want to know….” I was like, “Is this ridiculous?” And he’s like, “No, no, it’s fine. It’s gonna work. We have work to do, but it’ll work.” T Bone introduced Mike and I to someone named Ron Browning. and Ron is a genius — he’s a vocal coach out of Nashville who works with Alison Krauss and all these incredible people. From there we worked with Ron and T Bone up until right before we started shooting, up into the pre-records. And then (it was) Rachael Moore, who’s a huge standout, and a music producer on this. I am excited for her to have this moment, because she’s worked with T Bone for years and hasn’t really had this kind of opportunity. Once we got on-set, it was her and Ron every day. We did all the singing live, and it was so scary, but I felt like I was in really good hands. I’m excited to celebrate her, because just in the same way that it was tough for Tammy in 1960s Nashville, it’s still tough for women in country music in Nashville. And so for Raechel to have like this spotlight on our work, I think, is a really cool thing.

Michael, anything for you that stands out from working with people that helped you find a way into how you were going to sing your way through this?

Shannon: “There’s a reason God put your nose in the middle of your face.”

Chastain: [Laughs.] Ron Browning.

Shannon: That’s what Ron Browning used to say all the time. Because he was trying to get us to use our nose horns, and get our voices in our nose, which is not something… I don’t think, Jessica, when you were at Juilliard, there was anybody talking about the nose horn in voice class. I certainly was not familiar with the nose horn. I always thought you were supposed to just put it on the back of your teeth… You always think, “Well, I’ve got this big high note I’ve gotta hit — I better take a big gulp of air.” And Ron would say, “Don’t breathe at all. And as a matter of fact, push your stomach out.” The opposite of taking a deep breath. There’s no way that it’s gonna work — and then it works. So it’s little tricks like that.

That’s interesting. You had mentioned the nose before, and there is an aspect in which you listened to George Jones and it’s a little bit “nasal,” which is usually a term people use derogatorily. But he’s considered the greatest country singer of all time, so there’s nothing derogatory in that for him.

Shannon: Well, and it’s not just George. I mean, a lot of country singers — it’s a style of singing in country, I think.

Chastain: The honk.

Shannon: Yeah, it’s the honk — but it’s also a great resonator. Actually, you can sing much more quietly and be heard just as effectively, as opposed to trying to build, you know? I’d be singing this song that is just full of passion or longing or loss or suffering, and he’d say, “Just sing it like me and you are sitting at a bar and you’re telling me a story, and that’s it. You’re just telling me a story. And just do it like you’re bored, like you’ve told this story a hundred times.” And it would be at such odds with what you thought, you know: “Oh, I’m supposed to be making this amazing, dramatic moment happen.” And he was like, “No, that do the opposite.”

Jessica, you were so great as Tammy Faye Bakker (in her Oscar-winning turn in “The Eyes of Tammy Faye”), and there you’re dealing with someone who has maybe more spirit than natural giftedness as a vocalist. Here, you’re dealing with somebody who’s really known as technically a good singer. Were you able to immediately shed all the stuff that you did to make Tammy Faye work? Or did you ever find any of the last role creeping over, a bit?

Chastain: Oh, no, I didn’t have any crossover for this. I mean, it’s interesting because I worked with Dave Cobb on Tammy Faye, and it probably happened the way it was supposed to, because I was so shy. Dave was amazing at just getting me to open up, and he kept jacking up the keys to what I’d sing, even higher than sometimes Tammy Faye would do, because he wanted it to sound like I was like beyond my reach, because that’s Tammy. She was always like reaching to the heavens. And maybe being so uncomfortable and so out of my comfort zone in that situation helped me as a stepping stone.

Tammy Wynette had a lot more variations and dynamics in her voice. But also, she hated the way she sounded on “Stand by Your Man.” … Her vocal on “Stand by Your Man” is incredible, but she felt so self-conscious. To her, she said, it felt like a pig squealing. And I think it’s because it comes from a place so deep inside of her. It’s like the girl who was electrocuted, who got electric shock therapy. It’s that kind of noise coming out of her. It makes it so powerful. … I’d always have that moment right before the end of that song where I’m like, “OK, I don’t know if I’ll make it, this take. Here we go.” And it made me feel better to think Tammy also had that. She had little hand gestures behind her back to let the band know whether or not she’d hit the notes. That’s a scary song.

Michael Shannon and Jessica Chastain in ‘George and Tammy’ Dana Hawley

Obviously there’s no hero and villain in this story. There’s a lot of codependency, possibly both good and bad. There are very few movies or series that dramatize what happens after a breakup, if people are still at the very least friends. You could say with them that it was partly on a professional level, because they were known as a duo and continued to be. But beyond that, was it really just true love that was just meant to be? What was sort of your take on being able to take a story that could be predictable in some ways about the rise and fall of a relationship and then be able to take it into all these different ambiguous areas?

Shannon: Well, as far as I can tell, it seemed pretty true to life — and, like you say, not as much of a pure slope as these (dramatized) things tend to be. Because that’s more what life’s like. It seemed more true to life that way. It’s hard to say with absolute certainty what happened between these two people. And the hardest part to judge is the moments where they were really truly alone and there wasn’t a big chaotic conflict going on, but they were just together. And what drew them together in the first place and kept them together… even though they divorced, they were very important to one another for their whole lives. So, I think that’s one of the strongest things about the story, really, is how it’s not cut and dry, really — what love is or what form it’s supposed to take or how long it’s supposed to last or how you’re supposed to do it. It really kind of captures how mercurial and enigmatic love can be.

Chastain: Yeah. For me… Mike and I would watch a lot of the performances of them on YouTube. YouTube’s amazing to see them, and when they performed when they were married and when they performed when they were divorced, and there was always something incredibly magical. They knew they were on stage, but it was like they were the only two people in the world, and there was a very special energy there. That’s what I felt like I really wanted to show in this series.

Michael Shannon and Jessica Chastain as ‘George and Tammy’ Dana Hawley

Michael Shannon and Jessica Chastain at the premiere of Showtime’s “George & Tammy” held at Goya Studios on November 21, 2022 in Los Angeles, California. Gilbert Flores for Variety