The earphones are equipped with different sensors that can determine if they are being shared by multiple users, according to the patent. The earphones can take different actions based on whether there are one or two users.
For example, if a single user is detected, the headphones may play music in stereo sound (when the left and right earbuds receive different elements of sound). However, if there are two users, the headphone might play mono signals, so that both users hear the same audio content. It could even play a different song to each user.
Most of the sensors would be placed around the Y-junctions of the headphones, where they would be able to measure the angle between, and the position of, the left and right earphone cables.
Here's a diagram:
Or, Apple could use overlapping conductors right in the centre of the Y-junction, which would spread apart as each cable moves apart indicating there is more than one user, the AppleInsider report added.
The patent also said that the earphones could use a fibre optic goniometer, which measures precise angles using light. This would mean passing light through fibre optic cables to be collected in sensors in the earbuds:
The patent was first filed for in 2012 and credits Paul G. Puskarich as its inventor.
Since Apple is notorious for filing - and winning - patents without ever creating the product, there's no telling when these headphones could make it into your ears.