I work on the Android frameworks team, where I work on fonts and text rendering. As a 20% project, I also tinker with audio and synthesis. I presented some of this work, with my colleague Glenn Kasten, in the High Performance Audio session at Google I/O 2013.
The source code for the synthesizer is at code.google.com/p/music-synthesizer-for-android/.
There's also a simple app for testing your Audio Buffer Size.