Music professors have launched a campaign to clarify copyright rules that, they say, are hampering their research and holding up publication of books and papers.
They are calling on publishers to back Royal Musical Association guidelines that seek to define what proportion of music or lyrics can be quoted for academic purposes without copyright holders' permission.
Sheila Whiteley, professor of popular music at Salford University, said clarification was needed because copyright holders were increasingly litigious. Thus publishers often asked authors to seek permission from copyright holders when it might not be necessary.
She said that authors were left chasing permission, often from multiple copyright holders, who frequently took months to respond to their requests and sometimes refused permission on questionable grounds.
Even when permission is granted, the author can face copyright fees of more than £1,000 a book. Copyright permission is usually needed to reproduce the work of artists who are still alive or who have died in the past 70 years.
The music industry clampdown on the downloading of music, music samples and lyrics from the web has had a knock-on effect.
Professor Whiteley said: "There may be things you want to highlight in the music, such as the shaping of a Jimi Hendrix guitar solo or the way Bjork's voice is used. Often in those cases, the copyright holders say 'no' even though it might be just a few bars."
The RMA suggests that authors should be allowed to reproduce up to 5 per cent of a piece of music or lyrics for the purposes of analysis or review without having to seek permission.
Sarah Faulder, chief executive of the Music Publishers' Association, said publishers would insist on copyright permission only if they felt authors were "overstepping the mark".