Audio beacons can synchronize and/or relay data to devices through a variety of broadcast media. This data-over-audio method uses sound waves in a similar way to how Bluetooth employs electromagnetic waves.
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Android/XTUltrasonicsDemo Merge pull request #6 from jamrader/audio_updates Oct 21, 2017
iOS Update ViewController.m Oct 21, 2017
LICENSE Update LICENSE Jan 25, 2017 Update Jul 26, 2018

Welcome to the world's fastest, longest-range data-over-audio solution.

Send hundreds of bits/second via inaudible, high-frequency sound waves. Unlike any competing data-over-audio solution, which work only in quiet environments over short distances (a few cm to 3 meters), CUE Audio's solution has successfully broadcasted ultrasonic signals in outdoor environments to crowds of 80,000+ stadium attendees, with a propogation distance of over 150 meters and negligible latency above the speed of sound.

NOTE: THE GITHUB VERSION OF THIS LIBRARY HAS BEEN DEPRECATED. For inquiries about the latest commercial SDK, please visit

CUE Audio

This is a protocol for relaying data through inaudible, ultrasonic sound waves, essentially converting any speaker into an “Audio-Beacon.” This communications protocol utilizes sound waves in a similar way to how Bluetooth employs electromagnetic waves, offering an alternative method for transmitting data for both iOS and Android.

Advantages include:
  • No reliance on a data connection, including Wi-Fi, Bluetooth, or cellular service.
  • Ability to imperceptibly transmit data through online videos, television broadcasts, or any other sound-based media.
  • Enhancing the second-screen experience by allowing mobile devices to be informed of not only of what you are watching, but exactly how far along you are in the program. This also allows second-screens to respond to live events, such as touchdowns or breaking news.
  • Enabling proximity-awareness in slow zones and dead spots using existing speaker infrastructure.
  • Ability to synchronize devices to the nearest eighth of a second.

Who’s using CUE Audio?

CUE Audio have been enjoyed by over 5,000,000 users across three continents. Some of our clients include the following:

Purdue University Maquette University University of Michigan University of Alabama

University of Notre Dame University of Wisconsin Clemson University University of Nebraska

University of North Carolina Oklahoma City Thunder Atlanta Hawks Florida Panthers

More clients can be viewed here.

Possible uses

  • Triggering commands on the smartphone through a television broadcast, online video, radio commercial, film and movies. Users can be rewarded for tuning in; products can be linked to during a featured commercial; coupons can be distributed, etc.

  • Turn $10 household speakers into iBeacons. Any speaker emitting a unique fingerprint at regular intervals can be used to detect proximity and trigger events to achieve the same effect as traditional Bluetooth beacons.

  • Location-based “push” notifications. Users can be segmented by proximity to various speakers.

  • Smartphones in the same room or across the globe can be synchronized and given precisely timed commands in real-time, or minutes, hours, or even days after the trigger was detected.

Villanova @ Purdue | Iowa @ Purdue | Villanova @ Marquette

  • Commands without a data connection. Because the software is triggered by sound, it can perform even where there is no data connection, Wi-Fi, or Bluetooth.

  • Authorization/ticketing — triggers can be used to verify check-in at an event, or to unlock content on your app.

  • Indoor location sensing — provide location services more accurate than GPS by making use of the existing speaker infrastructure.

  • Wherever your imagination takes you.

How it works

Any speaker can become CUE-compatible. CUE Audio is powered by ultrasonic fingerprints, each of which is composed of a permutation of inaudible tones lasting between 0.0005 and 0.002 seconds. The duration of the fingerprint is variable and depends on the amount of data relayed — typically a complete trigger lasts anywhere from 0.30 to 2.0 seconds. Over the course of a second, thousands of bits of data can be relayed. Our ultrasonic signals are concentrated between 18-20 kHz to minimize conflict with environmental noise and to remain human-inaudible. This means that any audio containing our triggers must be in a format that supports high-pitch frequencies (e.g., WAV) and should not be converted or compressed into a lesser format (e.g., MP3).

Ultrasonic fingerprints can be generated to the point where single-use/throwaway triggers can be utilized for authorization and validation purposes, such as check-ins, private keys, and even payment processing.

To receive WAV files beyond those included in the starter pack, please contact