Lisnr uses ultrasonic audio called “Smart Tones” to transmit information between devices via sound that is inaudible to human ears. The tones can be added to existing media, for example music being played by a DJ, or transmitted on their own. To recognize the tones, guests must be using an app that has the Lisnr API embedded in it as well as enable the microphone on their device. Once that microphone is enabled, the app does not need to be open—which minimizes battery drain—and guests don’t need to have connectivity. In October, Lisnr announced a partnership with Splash, an event marketing platform, to create Smart Tone Ticketing. Attendees receive a Smart Tone ticket via email that can be used to check in at an event, without the need for Wi-Fi, Bluetooth, or any other form of connectivity.