This volume in the Technical Acoustics Expertise series describes the known passive, reactive and active airborne sound-absorbing materials and components with their different mechanisms of action and designs. It also covers the variety of options available today for soundproofing loud devices and systems by preventing reflections from walls and absorption in ducts, enclosures and shielding. Readers will learn how suitable sound absorbers can be used in rooms used for communication to optimise the acoustics with regard to the clarity of speech and music.