Health experts in the US have been urged to once again study the age old question: do loud noises damage your hearing? While not everyone knows exactly how loud music needs to be in order to cause some sort of hearing loss, there is a common sense limit that many people just choose to ignore.
Personally, I think a good idea would be for Sony to set a mark on the iPod volume control, showing the recommend highest volume limit. While damage to hearing does depend on the volume and length of listening time, it would be nice for your average Joe to have something to go by. Some have called for Sony to actually limit the iPod's maximum volume, which seems more like controlling rather than informing the consumer.