SIR Willard White speaks in the same subterranean purr as he sings.

"My voice was always low," he says. "When I was about nine or 10 people would ask me, 'boy, where'd you get that voice? You sound like a grandfather,' they'd say."

White, one the great bass-baritones of our age, was born in Jamaica and still talks with a Caribbean lilt, especially when the conversation turns to his childhood or Usain Bolt. He didn't grow up around classical music and signed up to study Economics at university – "in Jamaica a man had to have a upstanding profession," he says. But during a year of work experience he found himself dissatisfied. "I wasn't good at it. My heart wasn't in it. In moments of difficulty I would turn to singing and would feel different: more rejuvenated, more ready to face life."

He hadn't had much formal training but his parents bought him a ticket to New York where he enrolled at the Julliard School. "In my first few months I began to realise what I had embarked on," he says. "I was nearly paralysed with fear. The weather began to change from summer to autumn, something I had never experienced before. And there were many musical challenges.

"I wanted to go back home to security. But how could I have looked in the mirror? I gave myself two years to find out if there was anything there for me to work with. And here I am."

He's now 65 and one of the most distinct voices, and characters, in the business. He says the two are inseparable: "My vocal mechanism is a large part of the way I think about life. Why do I have this voice? Where does it come from? I cannot manufacture it. If I try to force it or hold it, it doesn't serve me so well. I just need to respect it and foster the conditions for it to work its best. Just like life: you are in it, so let go and just flow."

White doesn't do small talk or small ideas. Even the most mundane questions elicit profound analogies and soul-searching. He tells me about an incident, years ago, when he was sitting outside his dressing room in Amsterdam. "I was reluctant to join the others in the canteen where there was a lot of laughter. "I thought it was superficial laughter and I felt alone. A colleague came out of her dressing room and said 'Willard, you look like you're down in a hole. I'm going to come sit with you in that hole.' I realised that all I wanted was a sincere exchange."

AND that yearning for sincerity comes across in every bit of White's musicality, whether he's singing Bartok's Bluebeard, Gershwin's Porgy or Wagner's Wotan, as he did for Scottish Opera in the early 1990s. Tonight he's in Edinburgh with the Scottish Chamber Orchestra to sing Shostakovich's Symphony No 14. The work sets 11 poems, mainly dealing with death, and is more sombre song-cycle than conventional symphony. White describes it as "always a challenge. There's great power in it. It's a wonderful look at the human journey without trying to supply any answers, but just opportunities to reflect."

As for working with Robin Ticciati, the SCO's principal conductor? "He's very impressive. Very engaging, very sympathetic, very clear – and very young. He has the courage to express his individuality despite his age. Some people wait a long time to exhibit this – we call it maturity. He already exhibits it. If he starts from there he can only go up."

Sir Willard White is at the Usher Hall tonight.