There are good number of studies done to find if Ipod hearing or other MP3 players can lead to hearing loss. Most of them have found surprising things about these hi tech music instruments. The main reason behind this is human behaviour and also to experiment with all kinds of music.
Many teens or young adults have a risk of hearing loss in future because of higher than usual volume of music heard with the ear phones and ear buds. Currently the number is between 7% to 24% as a research indicates and this can be increased if not educated on this. Most of the children do the opposite if you ask them to lessen the volume of the sound. In fact they fail to realize that the music is turning into noise more than the moderate levels. It damages the hair cells in the ear which transforms sound waves to the electrical signals that the brain understands as sound.
A study on 30 subjects using Ipods conducted by Colarado University and Boston Children Hospital, Led by audiologist Portnuff found that teens not only tend to play music louder than adults, but they are often unaware of how loud they're playing it. Portnuff says "I honestly don't believe that most people understand they are putting themselves at risk, or at what level of risk,". He also says that the softer the volume the better it is. One can tune to 70% of volume and listen for 41/2 hours and may be for 90 minutes a day at 80% volume is probably safe for long-term hearing — a useful cutoff point to keep in mind. The risk of permanent hearing loss, as Portnuff says, can increase with just five minutes of exposure a day to music at full volume.
Also that a study done an NW University in Illinois recommends 60 / 60 which means that 60% of volume with 60 minutes of music per day is good to prevent the hearing loss.
A clear recommendation is that traditional head phones are better than the meatal ear phones or ear bud like recent ones. These transmit a 9 dB more than the traditional ones. Of course noise cancelling headphones are still the best.
Hence it is right time to think about the volume and the duration of the hearing music with I pods and MP3 players with ear buds and ear phones. I hope most of you have taken off the ear phones by now.