The rise of Ceu from a chaotic Brazillian city to biggest coffee shop chain

'You have to love Sao Paulo to live in it," says singer Ceu of her home town, the biggest city in the southern Hemisphere. "It's very ugly, aggressive and chaotic, with too much traffic and pollution. But musically the whole of Brazil is here. Because this is where it's happening." There's a certain kind of female voice that epitomises the idea of Brazilian music - with a cool, bright siren tone, a kind of butter-wouldn't-melt-in-the-mouth quality which, for the international listener at least, goes straight back to the early Sixties heyday of bossa nova, to Astrid Gilberto and The Girl from Ipanema.

Ceu's voice has precisely that quality, its ethereal nonchalance illuminating the eclectic moods of her latest album Caravana Sereia Bloom.

Yet where the great bossa nova figures of the past were all associated with the privileged beach-lounging world of middle-class Rio de Janeiro, Ceu's voice and experimental approach were formed amid the smog-choked high rise of Sao Paulo - a city now nearly twice the size of Rio; where the use of private helicopters is the highest in the world, but misery abounds along with massive social problems which, as Ceu puts it, "aren't shifting". Does she see herself as a kind of Astrid Gilberto of the postmodern megalopolis?

She laughs at the idea. "If people want to see me as that… great! That's not how I see myself. It's only when you go outside Brazil that you realise what the rest of the world thinks of as Brazilian music." Indeed, while everyone in Brazil knows the figures who sum up Brazilian music in the international mind - the likes of Antonio Carlos Jobim, Gilberto Gil and Caetano Veloso - these names represent only a small part of what people listen to in Brazil today.

Over the past decade the British market has been hit by a huge diversity of Brazilian sounds, from rustic accordions to hard-core political hip hop.

With it has come a whole regiment of cool-voiced young divas, all purporting to be the authentic female voice of the new Brazil: Sabrina Malheiros, Cibelle, Tulipa - the list is long. But the name and voice that have stuck in my mind are those of 31 year-old, three-times Grammy-nominated Ceu.

Born Maria do Ceu Whitaker Pocas into a middle-class family, with some far-distant British ancestry, Ceu - meaning sky or heaven - sees it as in her nature to mix music and everything else.

"Culturally, racially we are all a mix in one way or another. I didn't grow up listening only to samba. I don't come from a samba milieu. My father was a composer, so I was absorbing classical music and jazz alongside Afro-Brazilian rhythms.

"Brazil is like a continent. If you go to the far north, the west, the south, it's like a different country with completely different music. And all these musical cultures are here in Sao Paulo, because people come here to work. And all this feeds into what I do."

A talented draughtswoman, Ceu expected to follow a career in art until she developed a passion for performing in front of the mirror at the age of 15. A year spent staying with an aunt in New York broadened her horizons, but she realised she would have to return to Brazil to fulfil her musical vision.

Her 2005 self-titled first album, a chilled blend of classic bossa-samba, dub, rock and edgy electronica seemed to sum up a certain experimental Sao Paulo spirit. It was also the first international release on Starbucks's Hear Music label, which boosted sales in America, but aroused some unease in the singer herself.

"My first thought was, No!" she says. "To be seen as part of a multinational coffee company! But they did a very respectful job in promoting it, and I realised it was just another tool in getting our music across."

If the follow-up, 2009's Vargarosa, distilled this palette of influences even more successfully, the feel of her current album is more difficult to pin down.

"Lyrically it's about the challenge to the musician of being continually on the road, and it's influenced by the kind of music you hear on the road in Brazil. Not the cool side of Brazilian music, like bossa nova, but truck drivers' music, cowboy music, Brazilian calypsos and lambadas."

For the non-expert listener, these intriguing-sounding sources will be less apparent than the eclectic left-field rock sound of her long-term musical collaborators: Pupilo and Dengue, the powerful, dub-flavoured rhythm section from the hugely influential political rock band Nacao Zumbi, and film composer-producer brothers Rick and Gui Amabis. While this conjunction of talents has gained a reputation as the creme de la creme of the Sao Paulo underground, they are perhaps acclaimed more outside the country than in.

Sustaining a vast internal music market, Brazil may present itself as "the country of the future", but things aren't easy for those trying to do something different in music.

"If your music is played in TV soap operas you'll sell millions. If not, you'll struggle. We're at the middle stage, which is the hardest place to be. There are a lot of small venues and plenty of big venues. But there aren't so many medium-size halls in Brazil. When you reach that level it's hard to know where to go." While this makes international sales and touring crucial to the development of her music, she has no intention of leaving Brazil, or Sao Paulo.

"The people I work with are a circle of friends who are always together and share a lot of musical interests. There's a rich urban culture of graffiti and music. People are very receptive. It's a hard city to live in, but it's definitely got something."