On my iPhone 4s it seems that the volume of my headphones are not very loud. When I am at the gym or on the train heading home I can sometimes hardly the music over what is going on around me, which is very annoying. I can't remember ever having this issue with my 3GS.
I have checked my volume and EQ settings and I have not noticed any changes.
Is the onscreen volume indicator showing its maxed out? If so, try another pair of headphones and see if the headphones are faulty.
If the problem persists, try doing a restore and see if that does anything. REMEMBER TO BACKUP FIRST!
If the problem STILL persists, you may just have a faulty headphone jack... Or possibly water damage in the headphone jack itself. If that's the case, take it into an Apple store and get yourself a new one.
Thanks for the info and I have done all of this stuff. My volume under Settings>Music>Volume Limit is all the way up, and is not locked. The EQ is turned off and I have tried other EQ settings with no change. I thought I was doing something wrong but it seems that this is just the way it is.
When I am in a call I can hear the caller somewhat well unless I am on the train riding home or something like that.
My music is so low that when I am at the gym and I can hear the music being played in the gym over my headphones.
Listening to Pandora is even worse...I know that the quality of music on Pandora is going to be noticeably less versus the music on my phone.