According to research, those who download 'free' music are also the industry's largest audience for digital sales

Piracy may be the bane of the music industry but according to a new study, it may also be its engine. A report from the BI Norwegian School of Management has found that those who download music illegally are also 10 times more likely to pay for songs than those who don't.

Everybody knows that music sales have continued to fall in recent years, and that filesharing is usually blamed. We are made to imagine legions of internet criminals, their fingers on track-pads, downloading songs via BitTorrent and never paying for anything. One of the only bits of good news amid this doom and gloom is the steady rise in digital music sales. Millions of internet do-gooders, their fingers on track-pads, who pay for songs they like – purchasing them from Amazon or iTunes Music Store. And yet according to Professor Anne-Britt Gran's new research, these two groups may be the same.

The Norwegian study looked at almost 2,000 online music users, all over the age of 15. Researchers found that those who downloaded "free" music – whether from lawful or seedy sources – were also 10 times more likely to pay for music. This would make music pirates the industry's largest audience for digital sales.

Wisely, the study did not rely on music pirates' honesty. Researchers asked music buyers to prove that they had proof of purchase.

The paper's conclusions emerge just as Sweden's Pirate Bay trial comes to a close. Pirate Bay's four defendants, who helped operate the notorious BitTorrent tracker, were sentenced to a year in jail and fined 30m SEK (£2,500,000) in damages.