As he heard the once-puzzling sounds fill the family home, they became less enigmatic and more beautiful and that which was strange became desirable. For a boy who started taking violin lessons aged six, learned the flute and the glockenspiel, and used to sing Gilbert and Sullivan and music from Broadway shows in an ensemble with school friends, such a cocktail of influences had a profound effect.

It created in Glass a composer who could embrace - and then incorporate - the unfamiliar into his work with ease. It made him into a figure who stirred strong emotions in the concert-going public: those who heard his work either loved it or (and this is particularly true of the academic world) felt they saw through Glass, darkly. It also made him open to every sort of dramatic venture which involved music.

He is in Hong Kong this week to perform, with the Kronos Quartet, the score he wrote for the 1931 film of Dracula. Glass is well known for live performances of his work against the backdrop of film: his last visit to Hong Kong, in 1994, was to play the music he wrote to accompany Koyaanisqatsi.

The moving image has a strong attraction for him: he wrote the film scores for, among others, The Truman Show, The Thin Blue Line, Mishima and Kundun.

In this instance, Universal - what he rather quaintly calls 'the picture company' - approached him about doing a score for one of three films, all made at the beginning of the 1930s: The Mummy, Frankenstein or Dracula. 'I wanted to do all three but I picked Dracula because the performance of Bela Lugosi [who plays the blood-sucking count] is so outstanding, it was so powerful, it made it the most interesting of the three films.'

Glass - affable, good-humoured and a good deal more laid-back than some of the more jagged, frenzied moments of his scores might suggest - is evidently a man who likes human contact (he's the sort of individual who taps people gently on the arm to reinforce a point and make a fleeting connection). He has also said that a crucial part of performance for him is that it recaptures the moment of creativity, that playing his work is the second half of the creative process. So it's not altogether surprising that he likes going on tour and presenting his work to audiences on a global basis - unless, of course, you're Universal, in which case it is surprising, because this wasn't exactly what they had in mind when they approached him.

'At first, they wanted to look at the lighting design and production, and then it turned out no one there knew about live performance anyway, so they gave up and said we could do it.'

Dracula raised themes which Glass was intrigued enough to explore: 'Immortality, passion and death. People in the 19th century were interested in the idea of the pact with the devil, that you would trade your immortal soul for pleasure, like Faust. Bram Stoker [who wrote the novel Dracula] took those themes and added new elements. It's erotic and sensual, it's not about horror at all - there's one drop of blood in the whole film.'

Musing on the crucial, charismatic difference between Count Dracula and the monster in Frankenstein, he adds: 'We never feel that the monster is misunderstood.' Is he? Glass grins, amenably, seeing exactly where the question is headed. In the early days of his performances, back in the 1960s, audiences were so astounded and aggrieved by what they felt was an aural assault, that they left (often flinging rotten fruit on stage as they stomped off). In those days, he used to begin his recitals with a piece entitled Music In A Similar Motion which was a sort of early-warning system, an hors d'oeuvre which signalled that the rest of the meal might not be digestible to those of a sensitive disposition.

'No, I don't think I'm misunderstood,' he says. 'I have a very big public now so I can hardly call myself that. I began in 1967, and in 1976 I was playing in the Metropoli-tan Opera House in New York. That's 10 years, I'd say that was very, very quick, wouldn't you? Astonishingly quick. I never expected to have a public so quickly. However, parts of the academic world have very little time for composers like me.'

Why? 'Envy. Of course, envy - how can you even ask? They think, 'Look at the life he has while I have to sit here and teach counterpoint to blockheads' . . . Once people caught on, I did fairly well. I'm not that sort of classic, experimental composer who sits around with no one listening to my music. I do 50 or 60 concerts a year myself.'

And that's not counting all the other productions of his works which go on without his presence. Still, even when the Metropolitan Opera Company produced his five-hour opera, Einstein On The Beach, in 1976, he kept renewing his taxi-driver's licence, just in case. (Many theatregoers are presumably still unaware that they are in the privileged position of being able to say they had that Philip Glass in the front of their cab once. He also worked as a plumber, a furniture mover and - in order to put himself through famed New York music school Juilliard - a crane operator.)

Einstein On The Beach, which was Glass' first collaboration with the director Robert Wilson, marked a crucial juncture in his life, so much so that he recorded the work twice. It was the first of a trilogy of 'portrait' operas: the others were Satyagraha, in 1979, which had Mahatma Gandhi as its central figure, and Akhnaten in 1984, which focused on a 'heretic' pharaoh of 14th-century BC Egypt.

Those three figures present aspects of Glass' own belief system: he studied maths and philosophy and is interested in Eastern religions. He was born Jewish but is now Buddhist, and established the Tibet House Cultural Centre in New York with the late Allen Ginsberg and Richard Gere; he had just taken part in its fund-raising concert in New York, a few days before he arrived here. 'No question, for the people there, it was one of the great evenings of their lives.'

Of his musical faith, he is what could be categorised as pantheistic: this, after all, is a man who has worked with Ravi Shankar (with whom he was supposed to play a concert in India next week which had to be cancelled after the earthquake), David Bowie, Brian Eno, Laurie Anderson, Paul Simon and Mick Jagger.

As that list suggests, he doesn't like to be hemmed in: the characteristic tonal repetition of his work is intended, like meditation, to open the mind, not close it.

What intrigues him are the themes of transformation and transfiguration which occur, for example, in his work on Jean Cocteau's La Belle Et La Bete and Frank Kafka's horrifying short story In The Penal Colony. That, of course, is another reason he was attracted to the story of Count Dracula, who elegantly flaps around a succession of gilded interiors - Glass describes his work on it as 'chamber music' because so much of the action takes place inside rooms - while seeking human blood. Part of Lugosi's transfiguration during the first-night performance on Thursday, it has to be said, was more inadvertent: it came from the curious effect of being able to see Glass and the Kronos Quartet playing blithely away on the other side of the screen while the count went about his sanguinary business.

On several occasions it looked as if the performers were about to become part of proceedings - most notably when a hand, issuing forth from a coffin, hovered over the cellist, Jennifer Culp, as if she, too, was about to get it in the neck. (At a meet-the-artists session after the performance Culp admitted to a sense of relief when the screen goes up at the end and the more usual relationship between audience and quartet is restored.) The 1931 film is not a silent one: there's a good deal of establishing chat at the beginning ('What! Visiting Count Dracula! But it's Walpurgis night!' etc) and those who could read the Chinese translation were at a distinct advantage over the rest of the audience struggling to listen to the words above the music. It can sound distinctly competitive: indeed, Michael Riesman, who conducted the performance, said afterwards: 'For us the dialogue is a nuisance, it would be nice to turn it off. But then you'd lose the wonderful intonations of Bela Lugosi.'

Lugosi, even when he appears to have a group of musical mannequins floating eerily across his face, is a treat. He was born near the western borders of Transylvania - Dracula country - so those ripe intonations are authentic even when he cries at one point, as he does with a delicious irony (given these particular circumstances), 'Ahhh! Wolves! What music they make!'

Glass knows how to return the compliment. 'Part of the pleasure in playing music in front of an audience is the energy that we get from the people out there, which means we're never tired after a performance. In this case, the vampires are the ones playing behind the screen.'

Philip Glass and the Kronos Quartet perform Dracula at Kwai Tsing Theatre Auditorium tonight. $140-$220. Limited tickets available