While Apple a Louisiana man is suing Apple and asking that company alter its iPod in order that users cannot play music at dangerous noise levels, the RNID (royal national institute for the deaf) has raised concerns that music fans are cracking codes already present on MP3 players that ensure that digital music players can not be played to loud.

The group has launched a campaign to raise awareness of the problems associated with playing music to loud.

RNID director of communications Brian Lamb said: "There are ways that noise limiters on some MP3 players can be overridden. We are seriously concerned that if the anecdotal evidence we have that people are cracking these codes is true, then it could become a widespread problem."

"RNID’s Don’t Lose the Music Campaign is very interested in working with manufacturers to ensure that warnings, regarding the risk of listening to MP3 players too loudly, are made more prominent both on and in the packaging of their products," he added.

RNID senior audiologist Angela King said: "There is a danger that long-term use of personal music players at high volume will permanently damage people’s hearing. RNID’s Don’t Lose the Music Campaign is urging people to be aware of the risks so they can continue to enjoy music for longer. Noise filters for in-ear headphones are available from many high street stores and regular breaks should be taken from listening."

The RNID gives the following guidelines for safer listening:

- Take regular breaks from your headphones to give your ears a rest.

- Turn down the volume a notch - even a small reduction in volume can make a big difference to the risk of damage to your hearing.

- Avoid using the volume to drown out background noise, for example the sound of the train or traffic. The RNID is offering details of additions to in-ear that help with this problem.