Full volume, here in the U.S., is around 110 to 115 decibels. In Europe, it is capped at around 95 to 100 decibels, which is still plenty of volume. So, with this in mind, half-way in the U.S. is around 55 to 60 decibels, and 60 decibels is the volume of a normal conversation. In Europe, half-way would be around 45 to 50 decibels. Keep in mind that this is where you are getting all of the sound in your ears. If you have the Apple Earbuds WITHOUT attachments like the Griffin EarJams, then you will not get all the sound in your ears. If you do have those attachments or have in-ears, then the previous numbers should be correct or close to correct. There is no reason why people should have to lsiten to their music above 70 or 75 decibels. If you constantly listen to music at 80 decibels all the time, you will eventually begin to lose hearing, but this is over a period of time of a good amount. Just be careful and don't turn up the volume so loud. I hope this helps any.
ROB C
**This information is based on songs at the same relative volume. Some songs are louder than others (I.E. The Beatles' "Blackbird" only reaches about 60% of the full volume level of a CD, while U2's "Vertigo" is at 100% CD volume capacity).