ABSTRACT
This chapter introduces the three kinds of rooms: Sabine rooms, flat rooms and long rooms and discusses Sabine and statistical absorption coefficients. It examines low-frequency modal description of room response and presents transient response of Sabine rooms and reverberation decay. The chapter explores porous and panel sound absorbers and looks at applications of sound absorption. Sound in an enclosed space is strongly affected by the reflective properties of the enclosing surfaces and to the extent that the enclosing surfaces are reflective, the shape of the enclosure also affects the sound field. In the low-frequency range, an enclosure sound field is dominated by standing waves at certain characteristic frequencies. Consider a diffuse sound field in an enclosure and suppose that a fraction of the incident energy is absorbed upon reflection at the enclosure boundaries. When a sound field decays, all of the excited modes decay at their natural frequencies.
