The Susurrus module plays sound. Its core decides, once per frame, which voices play, stop or change volume.
Each host's own mixer (XAudio2 on desktop, Web Audio in the browser) does the samples, so no managed code runs on
an audio thread.

Susurrus is the portable core: the backend interface (IModule) and a silent NullModule for headless runs.
Backends live in sibling projects.