Answer:
that might just be the headphone cord itself or it might be the port on the pc/phone
Step-by-step explanation:
i had this happen with my old droid razr hd i thought it was the aux cord on my speaker and head phones but i used the same things on a friends phone and they worked just fine and this might be do to an old or broken port on the phone /c my phone headphone port got used almost everyday and it was just the port you can replace this on some tech or you could just use bluetooth if the tech doesent have it buy and adapter.
hope this helps!!!