Why can I only hear on one side of my earpiece?

Every single ear piece I have used on my iPhone 4 spoils eventually and when this happens I can only hear on one side of it, which is always the left one if I recall correctly. I have already ruined about 5-6 pairs and some of there are the higher end, better ones like AKG. I can hear on both sides sometimes when the wires moves to a certain spot but it's troublesome to always stay there. Whenever i change to a new pair it's fine but it will turn to this state sooner or later, i don't know why. When i looked into the hole where the earpieces/earphones go on my iphone i can see that there's a small metal ball at one side (slightly displaced from the left) but not one at the opposite side, which is the right piece i can't hear from. Is there something wrong with my iPhone or my earpieces and can I fix it?

No you can't fix, the wires are probably destroyed an maybe they're just cheap. Go buy new ones

The problem lies with maintenance. It is essential for you to take care of earphones when you are traveling or even listening to them. The wires must be kept unfolded as far as it possible and ensure that there are no forces or stresses on the wire. You can try buying earphones that come with a case that protects it. When the wires in the earphones get cut, this happens quite easily, it really can't be fixed and you need to buy new ones. You must also take care about how you pull them out of your phone, do not pull the wire but the casing near the adapter. Lastly, do not sleep wearing your earphones as it is likely to get caught with some object and lead to the same problem again.