LONDON • Having machines write music is not new. In the 1950s, composer Lejaren Hiller used a computer to produce the Illiac Suite for string quartet, the first computer- generated score.
Since then, countless researchers have pushed that work forward.
But several start-ups are now trying to commercialise artificial intelligence (AI) music for everything from jingles to potential pop hits.
Mr Patrick Stobbs' Jukedeck, for instance, is looking to sell tracks to anyone who needs background music for videos, games or commercials.
The company charges large businesses US$21.99 (S$31) to use a track, a fraction of what hiring a musician would cost.
Mr Stobbs would not reveal how many tracks it has sold, but said that the British division of Coca-Cola pays for a monthly subscription.
Tech giants are also involved.
In June last year, Google Brain announced Magenta, a project that aims to have computers produce "compelling and artistic" music, filled with surprises. Its efforts so far do not quite fit the bill.
In September last year, DeepMind, the Google-owned British AI company, also released results of an experiment it undertook for fun.
DeepMind put samples of piano music into its WaveNet system, used to generate audio such as speech. The system, which was not told anything about how music worked, used the initial audio to synthesise 10-second clips that sound like avant-garde jazz.
IBM also has a research project called Watson Beat, which musicians will be able to use to transform their works' style, making songs sound Middle Eastern, for example, or "spooky".
Jukedeck's beginnings are somewhat surprising for a tech company.
Mr Stobbs and composer Ed Newton-Rex, both 29, founded it in 2012. They had been choristers at King's College School in Cambridge, England, and Newton-Rex went on to study music at the University of Cambridge, where he first learnt that AI could compose.
Jukedeck's system involves feeding hundreds of scores into its artificial neural networks, which then analyse them so they can work out things such as the probability of one musical note's following another or how chords progress.
The networks can eventually produce compositions in a similar style, which are then turned into audio, using an automated production program. It has different networks for different styles, from folk to "corporate".
The company only recently started experimenting with the artificial neural networks for the audio output as well as the composition. This should make tracks sound more natural and varied - more human, in other words.
Other companies working on AI music tend to involve musicians more directly in the process.
The Sony Computer Science Laboratory in Paris, for example, considers musicians essential to its Flow Machines project, which has received funding from the European Research Council.
The idea behind the project is to get computers to write pop hits, said Mr Francois Pachet, the laboratory's director.
He said: "A compelling song is actually a rare and fragile object. It can work only if all the dimensions are right: the melody, the harmony, the voice, the dress of the singer, the discourse around it - like, 'Why did you write this song?' No one is able to model all that right now and I'm interested in that problem."
Flow Machines' main system is a composing tool that works similarly to Jukedeck's: by getting a computer to analyse and learn from everything from Beatles' songs to dance hits. However, its output is then given to musicians, who are free to use, change it or throw it away as they like, at no charge.
About 20 acts have used the system, Mr Pachet said, some performing the songs they wrote using it at a recent gig. He is in talks with some well-known groups, such as indie band Phoenix, to try it and several albums will be released this year.
Musicians appear to enjoy it.
"I could never have written a song like the one I did without it," said Mathieu Peudupin, a French rock musician who goes by the name Lescop. "It drove me to a place I would never have gone myself."
He said it was like working with a bandmate, although he ignored most of its suggestions. "But what singer in the world listens to his bandmates?" he said, laughing.
Mr Pachet and Lescop said they did not think listeners would entirely accept computer-generated music.
"Music fans need to fall in love with musicians," Lescop said. "You can't fall in love with a computer."
But the founders of Jukedeck are less certain.
Newton-Rex sees AI changing the way people listen, especially if computers eventually "understand music enough to make it respond in real time to, let's say, a game or you going for a run", he said.