In Machine Acoustics the creation, transmission, and radiation of sound is treated using the model of the fundamental equation of machine acoustics. In doing so, direct and indirect sound radiation must be distinguished. In direct sound radiation, airborne noise is created directly by a machine. Contrarily, in indirect sound radiation the structure is initially excited to vibrate (structure-borne sound) and then emits airborne sound over its surface. Therefore, in addition to the emission and propagation of airborne sound, the work at our Research Group also includes the creation and propagation of structure-borne sound. More recently, adaptive systems are being used in acoustics that are aimed at reducing the noise (active noise control) or changing the noise (sound design).