FMOD - FMOD Studio is an audio middleware solution and engine for games.
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
OpenAL - OpenAL is a cross-platform 3D audio API appropriate for use with gaming applications and many other...
Proteus PCB design - Proteus PCB design combines the schematic capture and ARES PCB layout programs to provide a...
PortAudio - PortAudio is a cross platform, open-source, audio I/O library.
QUCS - Qucs, briefly for Quite Universal Circuit Simulator, is an integrated circuit simulator which means you are able to setup a circuit with a graphical user interface (GUI) and simulate the large-signal, small-signal and noise behaviour of the circuit.