Hi, welcome to Head-Fi, something something your wallet.
That would be probably a bad contact, like a defective plug, but usually those give either cut out the sound while you move the plug or just don't play at all on one channel. First of all, have you tried other headphones? Even cheap earbuds, just to know wether it's the Beats and not the player. If it is the plug you can cut it and solder in a new one, which will require buying some material, or you can have someone do it for you.
I should mention that you can get better sound for very cheap, in case you can't solve your problem and you want to get new IEMs. There's a thread specifically for asking advice on what to buy.