Testing with the headphones that have a different length, similar to a rope that is tied from strings. It can back up the metal cable with audio frequency inside the headset as well.
Test cable length to a different length, like a rope that had been tied from the line. It can back up with metal wire inside the headphones sound better.
Experimenting with different length of headphones with a string of the monopoly from late. It can backup metal wire pairs with frequency noise inside the headphones.