Apple's release of a software update to limit the volume level of its iPod music player confirms the product is flawed, US attorneys involved in a class-action suit against the company said.

A free software update allows owners of the iPod nano and the latest models of standard-sized iPods to set a maximum sound volume level, including a setting that lets parents establish limits for their children's devices, Apple said.

Attorneys from the firm Hagens Berman Sobol and Shapiro, representing iPod owners in a class-action suit filed in January, claim that US iPod users have not had access to the same protection offered to European consumers in 2002, thus endangering the hearing of those users.

Although the lawyers welcomed the new limit, they claim that the software update does not protect owners of earlier generations of iPods, nor other models, such as the iPod shuffle. They claim that Apple does little to educate consumers about the potential damage iPod use can do to hearing, with some models able to reach 130 decibels, they said.

In 2002, Apple limited the sound level of iPods sold in the European Union to 100 decibels in order to comply with a French law.