The future of tickets might be ultrasonic audio from your phone
 

Dealing with paper tickets may become a thing of the past if Ticketmaster's new "Presence" digital system takes off. The ticket agency worked with data-via-audio company Lisnr to implement a new ticketing technology that uses a ultrasonic audio broad...

https://www.engadget.com/2017/07/05/...c-audio-phone/