New noise regulations come into force this weekend but licensees are unaware that they may have to turn the volume down.
Under the Control of Noise at Work Regulations, which becomes law in pubs on Sunday, bosses must make sure staff are not subjected to noise above 87 decibels.
Barry Willson, licensee of The Temple Bar in Oxford, which has regular karaoke and live band nights, is one of many licensees unaware of the change.
He said: "I haven't heard of them. How the hell would I know what 87 decibels was? I think there are a lot bigger issues for the government to be dealing with than this."
Anita Phair of the Duke of Wellington in Wellingborough, Northamptonshire, added: "I'm not aware of any new legislation coming in. Obviously it is something that would worry us. One would have thought there would have been circulars coming round about this."
Cornish licensee, Alex Rutherford of The Studio Bar in Launceston, had only heard of the new regulations because he is also a sound engineer but feared it would have an impact on live music.
"With heavy metal bands, for example, it's pretty much impossible to go below 100 decibels. This could be a major problem for putting on some music acts."
But a spokesman for deaf and hard of hearing charity RNID said pubs may not face prosecution until July when local authorities receive official guidance on the laws.
Emma Harrison, RNID head of campaigns, said: "RNID hopes to help employers in bars, pubs and clubs follow the Control of Noise at Work Regulations which have come into force for the music and entertainment industry and offers information and advice on its Don't Lose the Music campaign website - dontlosethemusic.com."