ABSTRACT
The interaction of sound with the surfaces of an enclosed space comes under the purview of room acoustics. Room acoustics in earlier times was also called architectural acoustics and building acoustics, when the science and engineering of pleasant sound was the main objective. That was the time in which interest in machine-generated noise was not very important. Reducing sound from noisy machinery inside an enclosed space is much different from modifying an enclosed space to obtain pleasant sound. This chapter discusses the acoustic absorption materials and experimental determination of the acoustic absorption coefficient. It defines the concept of the average acoustic absorption coefficient that is representative of the sum total of all acoustic absorption materials within an environment. The chapter presents the equations for energy density that will help define the concept of Room constant and reviews the modal density of an acoustic volume.
