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+## Audio Latency Measurement ##
+
+Audio output latency as measured by WALT is the time that passes from the moment an application
+decides to output a tone until it can be detected via the headphone jack. Microphone latency is
+defined similarly.
+
+Audio signal for measuring microphone latency is generated as a square wave using the Teensy tone()
+function (currently at 5 kHz). The signal is attenuated by a simple circuit similar to the
+[ChromeOS/Android audio loopback dongle](https://source.android.com/devices/audio/loopback.html).
+
+Audio output signal from the phone is detected when audio line voltage crosses a predefined
+threshold (currently about 65 mV).
+
+Low latency audio IO on Android can be achieved via JNI C/C++ code.
+Documentation and sample code can be found on the
+[High Performance Audio website](http://googlesamples.github.io/android-audio-high-performance/)
+
+
+Superpowered Inc. maintains an open source app for measuring round trip audio latency - 
+[Superpowered Latency App](https://github.com/superpoweredSDK/SuperpoweredLatency).
+
+
+## Published round trip measurements ##
+* [Audio round trip measurements published by Android group](https://source.android.com/devices/audio/latency_measurements.html#measurements)
+* [Audio round trip measurements published by Superpowered Inc.](http://superpowered.com/latency)

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