This repo is the example made by Android Dev Summit using the oboe library demonstrating how low-latency audio can be achieved.
Clone this repo with the oboe dependency (git submodule) using this command:
git clone git clone --recurse-submodules https://github.com/kohnech/android-lowlatency-audio.git
and open it in android studio. Run it with AVD or an Android device and by tapping on the app screen you will hear a 50 Hz square wave with low latency output.
Add suport for audio input (mic) echoing to output.