San Francisco, March 29 (Reuters): Apple Computer Inc. said today it has introduced a software update for its market-leading iPod that lets parents set maximum volume limits on the popular music player, as concerns grow about the risks its earphones might pose for hearing loss.

The software update, which is available as a free download for the iPod Nano and fifth generation iPod, gives users the ability to set volume caps on the iPod and lock it with a combination code, Apple said.

The move follows a class action lawsuit that was filed against Apple in a federal court in California in January, which claimed that iPods could cause hearing loss because they have the capacity to produce sounds up to 115 decibels. The National Institute of Health said earlier in March that more research is needed to determine whether portable music players like the iPod increase the risk of hearing loss.