I made the Synthesis ToolKit (SKT) available as Arduino Library.
The Synthesis ToolKit in C++ (STK) is a set of open source audio signal processing and algorithmic synthesis classes written in the C++ programming language. STK was designed to facilitate rapid development of music synthesis and audio processing software, with an emphasis on cross-platform functionality, realtime control, ease of use, and educational example code.
Further details can be found on Github or in my synthesizer posts…