"I've worked in so many different directions that the audience covers a lot of different territories. If I only do something in one direction, considering what my fan base is, I would have a difficult time satisfying or reaching the vast majority of them," says Hancock over the phone from his home in Los Angeles.

"I've tried to figure out ways to do a lot of songs in a short time. Songs like , , are songs that a lot of people are very familiar with. They want to hear my take on them. What I don't do is play them like the version they have on the record. I wrote those songs a long time ago, and after a while you get kind of bored with playing them the old way. I have to breathe some kind of freshness into them, because if I'm bored, the audience is going to be bored, I can guarantee you."

Those three tunes provide only a superficial sample of a repertoire packed with self-penned jazz standards and pop hits. The very first track Hancock cut for Blue Note records in 1962, , made the top 100 in the pop charts. Mongo Santamaria's Cuban pop cover took it to the top 10 the following year.

In 1973, Hancock's album, and the hit single from it, , proved to be a groundbreaking fusion of jazz and funk, substantially outselling any other jazz album released up to that date in the process.

Then in 1983, with the album , Hancock forged a link between jazz and the nascent hip hop movement, connecting with the MTV generation with another big hit single, - promoted with an innovative music video directed by the Godley and Creme partnership, formerly of pop band 10cc.

"I had no idea that would be a hit or anything," Hancock says. "I was interested in doing because I was intrigued by this new sound, which was scratching. I guess good fortune was with me, and I happened to collaborate with the right people at the right time. I'm sure a great amount of the success was due to timing. I'm happy that I was open enough to hear the validity of that sound and not be stuck with a kind of elitist narrow attitude about jazz. I wasn't concerned about whether it was going to be jazz or not. I just wanted to make music."

In addition to all the records he has sold, Hancock has accumulated many shelves full of awards, including an Oscar for his 1986 soundtrack to the Bertrand Tavernier jazz movie , and 14 Grammys.

One of the two Grammy Awards he won in 2008 is particularly significant. His tribute to friend Joni Mitchell, , won the award for album of the year, and became only the second jazz album to do so in the history of the awards, the first being in 1965. Was he surprised? "I was shocked and thrilled," says Hancock.

"It gave me the opportunity to reflect on the heroes in the past upon whose shoulders I stand, who got Grammys, many of them, but never got album of the year. I was surprised at the success of all the records that I've had that were successful, so far as sales are concerned."

He insists that "there's no real formula for making a hit record", but admits that when he wrote he was following his commercial as well as his creative instincts. "I was thinking about the great jazz pianist and composer Horace Silver, whose compositions did very well," he says.

"His stuff was kind of funky, and I thought 'maybe because I'm from Chicago - a blues town, I've heard Muddy Waters and that's part of my background - maybe I can write something that's funky and jazzy at the same time', and that was . Anyway they [Blue Note for which Silver also recorded] told me 'Don't worry about cover tunes - bring us some more originals'. My first album [ , 1962] is all originals, which they never did for a brand new artist before."

Hancock's first two albums for Blue Note caught the ear of Davis, who invited him to join what became his "second great quintet" when it eventually settled into the classic line-up of Davis, Hancock, drummer Tony Williams, bassist Ron Carter and saxophonist Wayne Shorter. That band is widely regarded as the most important and influential small jazz group of the 1960s, and raised Hancock's profile to star level.

He maintained his solo career during his time with Davis, releasing three more albums for Blue Note, including featuring with its memorable riff, later sampled by Us3 for , and, on his final album for the label, the more exploratory .

He also learned some important music and life lessons from his boss. His training as a child classical piano prodigy and a youthful love of doo-wop groups had both helped shape his harmonic thinking, but under the influence of Davis he began listening more attentively to rock and R&B.

"I noticed that Miles was open," he recalls. "At his house there were album covers of Janis Joplin, Cream, The Rolling Stones, James Brown and other artists that were popular at that time, and many of whom are still popular today. Miles to me was the epitome of coolness, and I figured that if Miles was open, then it must be OK to be open. That really changed my life, and that's one of the things that I recommend to young people when they ask for advice. I say it's extremely important to be open to new possibilities," he says.

From the late 1960s onwards, Hancock has balanced excursions into electronic music with acoustic small-group jazz - often working with alumni from the Miles quintet, particularly Shorter - and guest appearances on albums by artists ranging from Mitchell to British synth-pop band Simple Minds.

Since the beginning of this century, Hancock's own albums have tended to be collaborative projects, from 2002's with trumpeter Roy Hargrove and the late Michael Brecker on saxophone, to 2005's featuring guest artists including Sting, Paul Simon, Annie Lennox and Joss Stone.

In 2010, , his most recent album, featured contributions from a varied musical cast including The Chieftains, Shorter, Seal and an international range of world music artists. The album reflects a strong interest in promoting intercultural understanding, which springs, he says, in part from the Nichiren Buddhism he has practised for more than four decades.

"That record was my attempt to demonstrate the positive possibilities for globalisation, and that is through global collaboration. What can be produced is something that no one culture can produce by itself," he says. "It's also a push towards what I believe should be the goal of human beings in this century, and that is to work towards a sense of being a global citizen and not just a national citizen."

In his eighth decade, Herbie Hancock has come a long way from the hotshot pianist of the early 1960s, the sophisticated funkster of the period, or the vocoder-processed singer who was briefly a pop star in the late 1970s with the chart singles and .

As one of jazz's most respected elder statesmen, Hancock is a Unesco goodwill ambassador for the promotion of intercultural dialogue, and an educator who lectures on music at the University of California Los Angeles.

Next month he will add one of this year's Kennedy Centre Honours to his long list of public and academic accolades.

"Those opportunities, like being a goodwill ambassador for Unesco and teaching, are huge benefits to me in the sense that they allow me to have some kind of positive input, and a voice that hopefully has a positive influence towards a more humanistic and ethical future," he says.

"I look for opportunities to serve humanity. My view of responsibility is much broader than it used to be when I was a younger musician. Music is so powerful. It affects the heart. It brings people together. It harmonises people. And the effect is palpable."