Danny O'Donoghue has just been challenged to find the highest note in his vocal range.
Quick as a flash, The Script star springs off the sofa and bounds over to a piano on the top floor of the BBC's Wogan House.
"We can test it out now, if you like," he says, as he works his way up the keyboard, pitching his voice to match each note until he can't go any higher.
"High G!" he exclaims, then descends the scale to find the bottom of his register.
"That's a three octave range," he eventually declares. "Not bad!"
A gregarious and excitable presence, O'Donoghue is especially proud of this moment because, two years ago, he nearly lost his voice for good.
The star had developed painful nodes on his vocal cords because, by his own admission, "I wasn't living the healthiest of lifestyles".
He says: "I was drinking, I was smoking, I was staying out 'til all hours of the morning, then getting up early, doing a radio show, doing a concert in the night-time and constantly getting on planes and trains and not looking after myself.
"And you know what? If you have bad stuff going in, bad stuff's going to come out."
It didn't help, he suggests, that his singing style sucked.
"It was all balls to the wall, veins popping out of my neck, chin out... Just bad technique.
"It was only a matter of time before something bad happened."
O'Donoghue went under the knife in January 2016 but, after two months of living in silence, he discovered his surgery hadn't been a complete success. Gravely, his doctor told him he'd need another operation.
"The first one was fine," he recalls. "The second one was terrifying because I was like, 'Why am I not able to sing? You told me I'd be able to sing after a month.'"
"I played it off like it was an easy thing, but it was awful. Now that I can sing again, I can talk about how terrified I was."
The fear was so bad that the star started making a "plan B".
"I would have kept it schtum and gone into production and writing," he says. "You wouldn't have heard singles from The Script any more."
But O'Donoghue is nothing if not a survivor.
His first shot at fame came in the 1990s, when he and The Script guitarist Mark Sheehan joined the short-lived and rarely-discussed boy band MyTown.
All floppy fringes and spangly jumpsuits, the group had a minor hit with Party All Night in 1999 - but fans of bizarre pop artefacts should seek out Girl In Tears, a toe-curling ballad that poses the question "Did you ever make love to a girl in tears/And wonder why she was crying?"
Needless to say, it wouldn't be released now.
MyTown were unceremoniously dropped in 2001, leaving O'Donoghue and Sheehan adrift in LA.
Rather than return to Dublin, they carved out a living as writers and producers, remixing songs for N'Sync and Britney Spears and playing with TLC. But O'Donoghue still itched to be on stage.
In 2005, he started work on a solo project, which morphed into The Script after drummer Glen Power flew to LA to work on the demos.
Their first album emerged during a turbulent period in which Sheehan's mother and O'Donoghue's father both died. Then Power fractured his skull falling over in a pub toilet and O'Donoghue was rushed to A&E with a collapsed lung.
He was still recovering when the band's first single, We Cry, entered the charts. Within three weeks, the band were back on the road, and in August 2008 their album debuted at number one on both the UK and Irish charts.
After all that hardship, the trio made the most of their success, recording four albums in six years and circling the world several times over.
They struck gold with their third single, Breakeven, which became a hit in America and is now taught at the prestigious Berklee College of Music - much to the bemusement of O'Donoghue, who says he's largely unaware of the "rules" of songwriting.
"But if you're all seeing this beautiful mathematics in it then, yeah, we definitely meant it!"
In the studio, the band have a mantra - "good is the enemy of great" - which encourages them to be ruthless with their material.
"It's very easy to get excited about something you just recorded," explains Sheehan. "So we sit on the song and see how we feel about it in a month's time.
"If you're still chomping at the bit to get it out, then it's a great song."
O'Donoghue's vocal problems gave them plenty of opportunity to let the music percolate in 2016.
They started more than 70 tracks - "the most we've ever written" - with the singer contributing ideas using a voice app on his phone.
It was "a whole new approach", which allowed the band to "change things up a little", according to Sheehan.
Musically, the band have indulged the hip-hop and R&B influences they toyed with less successfully in MyTown - but the bigger leap comes in their lyrics, most notably on the new album's title track, Freedom Child.
"Freedom Child was inspired by my son," says Sheehan. "After London Bridge, they were doing terrorist drills at his school - and he came home and he said, 'Dad, what is terrorism?'"
"He was only seven at the time... so I thought the best way to explain it was write a song.
"I think it resonated with him more than it would have if I'd tried to sit him down and talk about it.
"And now his favourite lyric in the song is the middle eight where we say, 'Put a flower in the top of a gun/Put confetti in an atomic bomb/It's time to change because we've seen enough/Instead of war we're declaring love.'"
They take the argument further on Divided States of America, which tackles gun violence and Donald Trump's border wall, while pleading for those on opposing sides to sit down and talk.
The band have received some flak for their foray into politics (The Irish Times branded their lyrics "hokey", "opportunistic" and "Bono-lite") but The Script insist they were never trying to write an academic thesis.
"For us, the whole album is like when you go to the pub and have a few pints with your mates," says O'Donoghue. "You have a lot of conversations, from politics to religion, without judging each other."
To reach agreement, he argues, "you have to put your hand in and go, 'Listen, let's talk.'"
This even applies to the politicians handling negotiations over Ireland's Brexit border.
"Just get them drunk. They'd be a lot more chilled out about it," says O'Donoghue.
"Especially," adds Sheehan, "after the tequila."
The Script's album, Freedom Child, and single, Arms Open, are both out now.