My iPhone 5 has a vibration problem, and other than that, the music on headphones is really weird. I can hear everything fine if the volume is about 75-80% but if I bring the volume down, then everything becomes distorted and the music has a lot of disturbance. It happened on all headphones that I tried it with (Apple and others). Also, it happens on all apps. I didn't notice it happening when I call someone and speak to them over the headphones. I can hear the other person clearly even if I bring the volume down. It's an odd problem, Im not sure if its the software or the hardware. I restored the phone a couple of times, even updated the software, but the problem persists. What can I do to fix it?