Cross-platform Audio Creation Tool
Cross-platform Audio Creation Tool (XACT) is an audio programming library and engine released by Microsoft as part of the DirectX SDK. It is a high-level audio library for authoring/playing audio that is written to use Xaudio on the Xbox, DirectSound on Windows XP, and the new audio stack on Windows Vista and Windows 7. Xaudio is an Xbox-only API designed for optimal digital signal processing.
Source: Wikipedia — Cross-platform Audio Creation Tool (CC BY-SA 4.0)