This is actually a bit weird problem. Whenever I plug in my earphones on my PC, I hear only the background sound. But if I press and hold the receiver button on my earphones, I hear both vocal and background sound. But when I plug the earphones halfway through, I hear both vocal and background sound but in mono, no stereo. This problem is killing me... I need a solution! I didn't have the problem before... * I tried cleaning the port on my laptop * I tried reinstalling my sound drivers
This is typically used for VOIP calls I would suspect (where it automatically reduces the volume so you can hear the other person).
First off, your jack plug has 2 black lines. This indicates stereo. If you only press it in half way through, only one of these makes a contact (hence the mono sound).