Matt Smith sounded just a little worse for wear last week during a phone chat between interviews for his series, “Doctor Who.”

“Please excuse my voice,” croaked the ever-polite star of the international hit. “I was singing last night and it sounds rather hideous. How are you, sir?”

It’s no secret that Smith and his co-stars, Karen Gillan and Arthur Darvill, often sing on set. That didn’t change in New York, where they took time out from their whirlwind press tour to listen to some live soul music—and ended up singing along.

There’s no singing in the two-part “Doctor Who” season opener, which debuts at 8 p.m. Saturday on BBC America. It’s quite the opposite, in fact. The time-traveling Doctor (Smith) and his companions, Amy (Gillan) and Rory (Darvill), along with the mysterious River Song (Alex Kingston), face a new and dangerous foe called The Silence in, of all places, the Utah desert. It’s the first time in the 48-year history of “Doctor Who” that the show has filmed in the U.S.

Despite his voice, Smith was able to answer a few questions about the new season, filming in Utah and what The Doctor thinks is cool.

Sounds like they are working you too hard.
Yeah, I know, right? It’s crazy.

Well let’s get right to it. Do you feel any pressure coming back after the first season was so successful?
No, you know. We shoot for nine months and its hard work. I just want it to be bigger and better.

What are some of the surprises you’ve found about The Doctor in the new season?
It’s a real journey of discovery this year for The Doctor, I think. He’s learning a lot about River Song, so therefore learning what, I think, comes to define who he is—without giving any spoilers away. I think Amy and Rory have a real dramatic journeys this year as well which The Doctor is obviously part of. The stakes are high for all of the characters, I think. They’re really exploring the dark side of them this year, what makes them tick.

I read that you’ve written some Doctor Who adventures for yourself.
Yeah I did, when I was going to play the part initially, I started writing short stories. I wrote one about Egypt and Albert Einstein, weirdly enough. The Doctor hung out with Einstein, and Einstein was actually really inappropriate and quite silly. But brilliant at the same time; The Doctor loved him for all those reasons. It was just sort of a way to feel connected to the part somehow.

Do you think [writer and executive producer] Steven Moffat will ever use them?
No, no. [Laughs.]

We all know the TARDIS is bigger on the inside. Have you ever come across anything else that’s bigger on the inside?
[Laughs.] Oh gosh, not really. That’s quite an interesting question. [Laughs.] Only the TARDIS.

The TARDIS has been around for 40-some years, but Bill and Ted kind of stole the idea with their phone box in the “Bill & Ted” movies. What makes The Doctor a better time-traveler than those two?
Oh man, well, Point 1, he’s more than 900 years old; Point 2, he doesn’t use violence; Point 3, he’s the most intelligent being in the universe, bar none; Point 4, he saves the world… And, you know, The Doctor’s just clever and cooler than them, I think.

You say he’s the cleverest person in the world, but what about River Song?
She’s the one person that makes him come unstuck…

Does The Doctor ever feel like a third wheel around Amy and Rory?
I think yes, more so than ever actually. And it’s weird, because you think perhaps that Rory would be the one out. But I think increasingly its The Doctor. He admires them both, kind of the way they’ve settled down, but he doesn’t quite understand it.

How was Utah?
Utah was great, man. I think the first episodes in America really up the scale and the scope of the show. We’ve made it as cinematic as we can. It was a privilege to film there when you look at the history of what’s filmed there before: several John Ford movies, and “Back to the Future” filmed there, and Forrest Gump stopped running there. To make “Doctor Who” a part of that was an ambition that we’ve realized. And I’m really pleased that it’s added to the scope of the show. We were just really excited to be filming in the States.

Do you think The Doctor will change his style and start wearing Western boots and Stetsons all the time now?
[Laughs.] Listen, all I know is that The Doctor loves a Stetson hat now. The Fez is out and the Stetson is in.

It’s cool, right?
[Laughs.] It’s cool! Exactly! Karen [Gillan] keeps telling me the fez is better. I’m like, “No way, man! The Stetson is better!”

Of all the things The Doctor says are cool, what’s the coolest?
Stetsons are cool. I think that’s his new one.

Mark Sheppard told me that he liked shooting with you guys, because you often spontaneously break into song on set. Are we ever going to see a musical episode?
[Laughs.] I don’t know. Maybe. Karen’s a great singer, but I don’t know if we’ll see a musical episode in my tenure. Who knows? You never know. Never say never.

What song do you sing the most on set?
We sing, what’s that tune? “Ring of Fire” by, um, what’s his name? [Sings] Burning ring of fire, down, down down—yes! Johnny Cash, man! We sing that loads.

On “Grey’s Anatomy,” the doctors are named McDreamy and McSteamy. What would your McNickname be?
Wow, that’s a good question. Strange Alien Traveling Man. No! Boy, boy, who knows? Something fun and inventive. Strange Alien Time Lord. {Not from Curt: No Mc's for Matt.]

Everyone is saying how dark this season is going to be. Is that because of the foes you meet?
Yeah, I think it is. But it’s also because of the journey the characters go on. We find who River Song is to The Doctor, and that story, as a narrative, it really plunges into The Doctor’s past and explores who he is. So therefore, by exploring him we find that The Doctor is sometimes dark. Not only that, [but] Amy and Rory have some huge storylines. A lot of cliffhangers are going to take place for them this season.

Tell me about The Silence.
Well, I think they’re one the greatest monsters in “Who” history. They’re a psychological monster. Steven has been very clever with the way that he’s created them. And I think they’ve been fully realized by the teams in Wales that make all that stuff happen. So I’m really proud of them. I think they’re one of the scariest monsters to date.

The Weeping Angels have been the scariest so far, in my opinion. Is The Silence scarier?
I think it’s the closest we’ve had to a Weeping Angel and they could be even better, yeah. They’re really brilliant.