The surface of each headphone supports touch controls.
Audio Controls
Swipe Up : Increase volume
Swipe Down : Decrease volume
Swipe Forward : Go to next track
Swipe Back : Previous track
Tap : Play/pause
Call Controls
Answer a call : tap twice
End a call : tap twice
Reject a call : Swipe backward
Swipe Up : Increase volume
Swipe Down : Decrease volume
Digital Assistant
If you have a default digital assistant enabled on your phone you can tap twice to activate the assistant.