This is a test app intended for software developers and OEMs to test Android MIDI on Marshmallow. The sound is not fancy. Just a sawtooth wave and an envelope.

You can connect a MIDI keyboard by USB or Bluetooth and play notes. Or drive the synthesizer from another MIDI app such as the Mobileer MidiKeyboard. Connect to the "Mobileer SynthExample[0]" port.

Complete source code is available on github under "philburk/android-midisuite".